v2: Rework hooks system (#516)

* ci: Remove plugin hook handler

* Rework error type from interface to struct

* Avoid writing to http.ResponseWriter directly

* Allow hooks to modify response

* Add example for HTTP hooks using Python

* Implement new plugin system using Hashicorp/go-plugin

* Enable returning partial HTTPResponses

* Remove some (unnecessary) error handling

* Forward stdout and stderr from plugin to tusd

* docs: Update examples

* cli: Update filehooks to new system

* cli: Renovate gRPC hooks

* docs: Correct casing of gRPC

* misc: Documentation, better examples, and code structure

.gitignore

@@ -5,3 +5,5 @@ node_modules/
 .DS_Store
 ./tusd
 tusd_*_*
+__pycache__/
+examples/hooks/plugin/hook_handler

cmd/tusd/cli/flags.go

@@ -38,6 +38,7 @@ var Flags struct {
 	AzObjectPrefix          string
 	AzEndpoint              string
 	EnabledHooksString      string
+	PluginHookPath          string
 	FileHooksDir            string
 	HttpHooksEndpoint       string
 	HttpHooksForwardHeaders string
@@ -46,8 +47,6 @@ var Flags struct {
 	GrpcHooksEndpoint       string
 	GrpcHooksRetry          int
 	GrpcHooksBackoff        int
-	HooksStopUploadCode     int
-	PluginHookPath          string
 	EnabledHooks            []hooks.HookType
 	ShowVersion             bool
 	ExposeMetrics           bool
@@ -91,6 +90,7 @@ func ParseFlags() {
 	flag.StringVar(&Flags.AzObjectPrefix, "azure-object-prefix", "", "Prefix for Azure object names")
 	flag.StringVar(&Flags.AzEndpoint, "azure-endpoint", "", "Custom Endpoint to use for Azure BlockBlob Storage (requires azure-storage to be pass)")
 	flag.StringVar(&Flags.EnabledHooksString, "hooks-enabled-events", "pre-create,post-create,post-receive,post-terminate,post-finish", "Comma separated list of enabled hook events (e.g. post-create,post-finish). Leave empty to enable default events")
+	flag.StringVar(&Flags.PluginHookPath, "hooks-plugin", "", "Path to a Go plugin for loading hook functions")
 	flag.StringVar(&Flags.FileHooksDir, "hooks-dir", "", "Directory to search for available hooks scripts")
 	flag.StringVar(&Flags.HttpHooksEndpoint, "hooks-http", "", "An HTTP endpoint to which hook events will be sent to")
 	flag.StringVar(&Flags.HttpHooksForwardHeaders, "hooks-http-forward-headers", "", "List of HTTP request headers to be forwarded from the client request to the hook endpoint")
@@ -99,8 +99,6 @@ func ParseFlags() {
 	flag.StringVar(&Flags.GrpcHooksEndpoint, "hooks-grpc", "", "An gRPC endpoint to which hook events will be sent to")
 	flag.IntVar(&Flags.GrpcHooksRetry, "hooks-grpc-retry", 3, "Number of times to retry on a server error or network timeout")
 	flag.IntVar(&Flags.GrpcHooksBackoff, "hooks-grpc-backoff", 1, "Number of seconds to wait before retrying each retry")
-	flag.IntVar(&Flags.HooksStopUploadCode, "hooks-stop-code", 0, "Return code from post-receive hook which causes tusd to stop and delete the current upload. A zero value means that no uploads will be stopped")
-	flag.StringVar(&Flags.PluginHookPath, "hooks-plugin", "", "Path to a Go plugin for loading hook functions (only supported on Linux and macOS; highly EXPERIMENTAL and may BREAK in the future)")
 	flag.BoolVar(&Flags.ShowVersion, "version", false, "Print tusd version information")
 	flag.BoolVar(&Flags.ExposeMetrics, "expose-metrics", true, "Expose metrics about tusd usage")
 	flag.StringVar(&Flags.MetricsPath, "metrics-path", "/metrics", "Path under which the metrics endpoint will be accessible")

cmd/tusd/cli/hooks.go

@@ -1,7 +1,6 @@
 package cli
 
 import (
-	"fmt"
 	"strconv"
 	"strings"
 
@@ -20,27 +19,12 @@ func hookTypeInSlice(a hooks.HookType, list []hooks.HookType) bool {
 	return false
 }
 
-func hookCallback(typ hooks.HookType, info handler.HookEvent) error {
+func preCreateCallback(event handler.HookEvent) (handler.HTTPResponse, error) {
-	if output, err := invokeHookSync(typ, info, true); err != nil {
+	return invokeHookSync(hooks.HookPreCreate, event)
-		if hookErr, ok := err.(hooks.HookError); ok {
-			return hooks.NewHookError(
-				fmt.Errorf("%s hook failed: %s", typ, err),
-				hookErr.StatusCode(),
-				hookErr.Body(),
-			)
-		}
-		return fmt.Errorf("%s hook failed: %s\n%s", typ, err, string(output))
 }
 
-	return nil
+func preFinishCallback(event handler.HookEvent) (handler.HTTPResponse, error) {
-}
+	return invokeHookSync(hooks.HookPreFinish, event)
-
-func preCreateCallback(info handler.HookEvent) error {
-	return hookCallback(hooks.HookPreCreate, info)
-}
-
-func preFinishCallback(info handler.HookEvent) error {
-	return hookCallback(hooks.HookPreFinish, info)
 }
 
 func SetupHookMetrics() {
@@ -113,35 +97,35 @@ func SetupPostHooks(handler *handler.Handler) {
 	go func() {
 		for {
 			select {
-			case info := <-handler.CompleteUploads:
+			case event := <-handler.CompleteUploads:
-				invokeHookAsync(hooks.HookPostFinish, info)
+				invokeHookAsync(hooks.HookPostFinish, event)
-			case info := <-handler.TerminatedUploads:
+			case event := <-handler.TerminatedUploads:
-				invokeHookAsync(hooks.HookPostTerminate, info)
+				invokeHookAsync(hooks.HookPostTerminate, event)
-			case info := <-handler.UploadProgress:
+			case event := <-handler.UploadProgress:
-				invokeHookAsync(hooks.HookPostReceive, info)
+				invokeHookAsync(hooks.HookPostReceive, event)
-			case info := <-handler.CreatedUploads:
+			case event := <-handler.CreatedUploads:
-				invokeHookAsync(hooks.HookPostCreate, info)
+				invokeHookAsync(hooks.HookPostCreate, event)
 			}
 		}
 	}()
 }
 
-func invokeHookAsync(typ hooks.HookType, info handler.HookEvent) {
+func invokeHookAsync(typ hooks.HookType, event handler.HookEvent) {
 	go func() {
 		// Error handling is taken care by the function.
-		_, _ = invokeHookSync(typ, info, false)
+		_, _ = invokeHookSync(typ, event)
 	}()
 }
 
-func invokeHookSync(typ hooks.HookType, info handler.HookEvent, captureOutput bool) ([]byte, error) {
+func invokeHookSync(typ hooks.HookType, event handler.HookEvent) (httpRes handler.HTTPResponse, err error) {
 	if !hookTypeInSlice(typ, Flags.EnabledHooks) {
-		return nil, nil
+		return httpRes, nil
 	}
 
 	MetricsHookInvocationsTotal.WithLabelValues(string(typ)).Add(1)
 
-	id := info.Upload.ID
+	id := event.Upload.ID
-	size := info.Upload.Size
+	size := event.Upload.Size
 
 	switch typ {
 	case hooks.HookPostFinish:
@@ -151,28 +135,43 @@ func invokeHookSync(typ hooks.HookType, info handler.HookEvent, captureOutput bo
 	}
 
 	if hookHandler == nil {
-		return nil, nil
+		return httpRes, nil
 	}
 
-	name := string(typ)
 	if Flags.VerboseOutput {
-		logEv(stdout, "HookInvocationStart", "type", name, "id", id)
+		logEv(stdout, "HookInvocationStart", "type", string(typ), "id", id)
 	}
 
-	output, returnCode, err := hookHandler.InvokeHook(typ, info, captureOutput)
+	hookRes, err := hookHandler.InvokeHook(hooks.HookRequest{
+		Type:  typ,
+		Event: event,
+	})
 
 	if err != nil {
 		logEv(stderr, "HookInvocationError", "type", string(typ), "id", id, "error", err.Error())
 		MetricsHookErrorsTotal.WithLabelValues(string(typ)).Add(1)
+		return httpRes, err
 	} else if Flags.VerboseOutput {
 		logEv(stdout, "HookInvocationFinish", "type", string(typ), "id", id)
 	}
 
-	if typ == hooks.HookPostReceive && Flags.HooksStopUploadCode != 0 && Flags.HooksStopUploadCode == returnCode {
+	httpRes = hookRes.HTTPResponse
+
+	// If the hook response includes the instruction to reject the upload, reuse the error code
+	// and message from ErrUploadRejectedByServer, but also include custom HTTP response values
+	if typ == hooks.HookPreCreate && hookRes.RejectUpload {
+		err := handler.ErrUploadRejectedByServer
+		err.HTTPResponse = err.HTTPResponse.MergeWith(httpRes)
+
+		return httpRes, err
+	}
+
+	if typ == hooks.HookPostReceive && hookRes.StopUpload {
 		logEv(stdout, "HookStopUpload", "id", id)
 
-		info.Upload.StopUpload()
+		// TODO: Control response for PATCH request
+		event.Upload.StopUpload()
 	}
 
-	return output, err
+	return httpRes, err
 }

cmd/tusd/cli/hooks/file.go

@@ -3,11 +3,10 @@ package hooks
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"os"
 	"os/exec"
 	"strconv"
-
-	"github.com/tus/tusd/pkg/handler"
 )
 
 type FileHook struct {
@@ -18,43 +17,50 @@ func (_ FileHook) Setup() error {
 	return nil
 }
 
-func (h FileHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput bool) ([]byte, int, error) {
+func (h FileHook) InvokeHook(req HookRequest) (res HookResponse, err error) {
-	hookPath := h.Directory + string(os.PathSeparator) + string(typ)
+	hookPath := h.Directory + string(os.PathSeparator) + string(req.Type)
 	cmd := exec.Command(hookPath)
 	env := os.Environ()
-	env = append(env, "TUS_ID="+info.Upload.ID)
+	env = append(env, "TUS_ID="+req.Event.Upload.ID)
-	env = append(env, "TUS_SIZE="+strconv.FormatInt(info.Upload.Size, 10))
+	env = append(env, "TUS_SIZE="+strconv.FormatInt(req.Event.Upload.Size, 10))
-	env = append(env, "TUS_OFFSET="+strconv.FormatInt(info.Upload.Offset, 10))
+	env = append(env, "TUS_OFFSET="+strconv.FormatInt(req.Event.Upload.Offset, 10))
 
-	jsonInfo, err := json.Marshal(info)
+	jsonReq, err := json.Marshal(req)
 	if err != nil {
-		return nil, 0, err
+		return res, err
 	}
 
-	reader := bytes.NewReader(jsonInfo)
+	reader := bytes.NewReader(jsonReq)
 	cmd.Stdin = reader
 
 	cmd.Env = env
 	cmd.Dir = h.Directory
 	cmd.Stderr = os.Stderr
 
-	// If `captureOutput` is true, this function will return the output (both,
+	output, err := cmd.Output()
-	// stderr and stdout), else it will use this process' stdout
-	var output []byte
-	if !captureOutput {
-		cmd.Stdout = os.Stdout
-		err = cmd.Run()
-	} else {
-		output, err = cmd.Output()
-	}
 
-	// Ignore the error, only, if the hook's file could not be found. This usually
+	// Ignore the error if the hook's file could not be found. This usually
 	// means that the user is only using a subset of the available hooks.
 	if os.IsNotExist(err) {
-		err = nil
+		return res, nil
 	}
 
-	returnCode := cmd.ProcessState.ExitCode()
+	// Report error if the exit code was non-zero
-
+	if err, ok := err.(*exec.ExitError); ok {
-	return output, returnCode, err
+		return res, fmt.Errorf("unexpected return code %d from hook endpoint: %s", err.ProcessState.ExitCode(), string(output))
+	}
+
+	if err != nil {
+		return res, err
+	}
+
+	// Do not parse the output as JSON, if we received no output to reduce possible
+	// errors.
+	if len(output) > 0 {
+		if err = json.Unmarshal(output, &res); err != nil {
+			return res, fmt.Errorf("failed to parse hook response: %w, response was: %s", err, string(output))
+		}
+	}
+
+	return res, nil
 }

cmd/tusd/cli/hooks/grpc.go

@@ -5,17 +5,15 @@ import (
 	"time"
 
 	grpc_retry "github.com/grpc-ecosystem/go-grpc-middleware/retry"
-	"github.com/tus/tusd/pkg/handler"
+	pb "github.com/tus/tusd/pkg/proto/v2"
-	pb "github.com/tus/tusd/pkg/proto/v1"
 	"google.golang.org/grpc"
-	"google.golang.org/grpc/status"
 )
 
 type GrpcHook struct {
 	Endpoint   string
 	MaxRetries int
 	Backoff    int
-	Client     pb.HookServiceClient
+	Client     pb.HookHandlerClient
 }
 
 func (g *GrpcHook) Setup() error {
@@ -31,44 +29,59 @@ func (g *GrpcHook) Setup() error {
 	if err != nil {
 		return err
 	}
-	g.Client = pb.NewHookServiceClient(conn)
+	g.Client = pb.NewHookHandlerClient(conn)
 	return nil
 }
 
-func (g *GrpcHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput bool) ([]byte, int, error) {
+func (g *GrpcHook) InvokeHook(hookReq HookRequest) (hookRes HookResponse, err error) {
 	ctx := context.Background()
-	req := &pb.SendRequest{Hook: marshal(typ, info)}
+	req := marshal(hookReq)
-	resp, err := g.Client.Send(ctx, req)
+	res, err := g.Client.InvokeHook(ctx, req)
 	if err != nil {
-		if e, ok := status.FromError(err); ok {
+		return hookRes, err
-			return nil, int(e.Code()), err
-		}
-		return nil, 2, err
-	}
-	if captureOutput {
-		return resp.Response.GetValue(), 0, err
-	}
-	return nil, 0, err
 	}
 
-func marshal(typ HookType, info handler.HookEvent) *pb.Hook {
+	hookRes = unmarshal(res)
-	return &pb.Hook{
+	return hookRes, nil
-		Upload: &pb.Upload{
+}
-			Id:             info.Upload.ID,
+
-			Size:           info.Upload.Size,
+func marshal(hookReq HookRequest) *pb.HookRequest {
-			SizeIsDeferred: info.Upload.SizeIsDeferred,
+	event := hookReq.Event
-			Offset:         info.Upload.Offset,
+
-			MetaData:       info.Upload.MetaData,
+	return &pb.HookRequest{
-			IsPartial:      info.Upload.IsPartial,
+		Type: string(hookReq.Type),
-			IsFinal:        info.Upload.IsFinal,
+		Event: &pb.Event{
-			PartialUploads: info.Upload.PartialUploads,
+			Upload: &pb.FileInfo{
-			Storage:        info.Upload.Storage,
+				Id:             event.Upload.ID,
+				Size:           event.Upload.Size,
+				SizeIsDeferred: event.Upload.SizeIsDeferred,
+				Offset:         event.Upload.Offset,
+				MetaData:       event.Upload.MetaData,
+				IsPartial:      event.Upload.IsPartial,
+				IsFinal:        event.Upload.IsFinal,
+				PartialUploads: event.Upload.PartialUploads,
+				Storage:        event.Upload.Storage,
 			},
 			HttpRequest: &pb.HTTPRequest{
-			Method:     info.HTTPRequest.Method,
+				Method:     event.HTTPRequest.Method,
-			Uri:        info.HTTPRequest.URI,
+				Uri:        event.HTTPRequest.URI,
-			RemoteAddr: info.HTTPRequest.RemoteAddr,
+				RemoteAddr: event.HTTPRequest.RemoteAddr,
+				// TODO: HEaders
+			},
 		},
-		Name: string(typ),
 	}
 }
+
+func unmarshal(res *pb.HookResponse) (hookRes HookResponse) {
+	hookRes.RejectUpload = res.RejectUpload
+	hookRes.StopUpload = res.StopUpload
+
+	httpRes := res.HttpResponse
+	if httpRes != nil {
+		hookRes.HTTPResponse.StatusCode = int(httpRes.StatusCode)
+		hookRes.HTTPResponse.Headers = httpRes.Headers
+		hookRes.HTTPResponse.Body = httpRes.Body
+	}
+
+	return hookRes
+}

cmd/tusd/cli/hooks/hooks.go

@@ -1,12 +1,58 @@
 package hooks
 
+// TODO: Move hooks into a package in /pkg
+
 import (
 	"github.com/tus/tusd/pkg/handler"
 )
 
+// HookHandler is the main inferface to be implemented by all hook backends.
 type HookHandler interface {
+	// Setup is invoked once the hook backend is initalized.
 	Setup() error
-	InvokeHook(typ HookType, info handler.HookEvent, captureOutput bool) ([]byte, int, error)
+	// InvokeHook is invoked for every hook that is executed. req contains the
+	// corresponding information about the hook type, the involved upload, and
+	// causing HTTP request.
+	// The return value res allows to stop or reject an upload, as well as modifying
+	// the HTTP response. See the documentation for HookResponse for more details.
+	// If err is not nil, the value of res will be ignored. err should only be
+	// non-nil if the hook failed to complete successfully.
+	InvokeHook(req HookRequest) (res HookResponse, err error)
+}
+
+// HookRequest contains the information about the hook type, the involved upload,
+// and causing HTTP request.
+type HookRequest struct {
+	// Type is the name of the hook.
+	Type HookType
+	// Event contains the involved upload and causing HTTP request.
+	Event handler.HookEvent
+}
+
+// HookResponse is the response after a hook is executed.
+type HookResponse struct {
+	// HTTPResponse's fields can be filled to modify the HTTP response.
+	// This is only possible for pre-create, pre-finish and post-receive hooks.
+	// For other hooks this value is ignored.
+	// If multiple hooks modify the HTTP response, a later hook may overwrite the
+	// modified values from a previous hook (e.g. if multiple post-receive hooks
+	// are executed).
+	// Example usages: Send an error to the client if RejectUpload/StopUpload are
+	// set in the pre-create/post-receive hook. Send more information to the client
+	// in the pre-finish hook.
+	HTTPResponse handler.HTTPResponse
+
+	// RejectUpload will cause the upload to be rejected and not be created during
+	// POST request. This value is only respected for pre-create hooks. For other hooks,
+	// it is ignored. Use the HTTPResponse field to send details about the rejection
+	// to the client.
+	RejectUpload bool
+
+	// StopUpload will cause the upload to be stopped during a PATCH request.
+	// This value is only respected for post-receive hooks. For other hooks,
+	// it is ignored. Use the HTTPResponse field to send details about the stop
+	// to the client.
+	StopUpload bool
 }
 
 type HookType string
@@ -21,29 +67,3 @@ const (
 )
 
 var AvailableHooks []HookType = []HookType{HookPreCreate, HookPostCreate, HookPostReceive, HookPostTerminate, HookPostFinish, HookPreFinish}
-
-type hookDataStore struct {
-	handler.DataStore
-}
-
-type HookError struct {
-	error
-	statusCode int
-	body       []byte
-}
-
-func NewHookError(err error, statusCode int, body []byte) HookError {
-	return HookError{err, statusCode, body}
-}
-
-func (herr HookError) StatusCode() int {
-	return herr.statusCode
-}
-
-func (herr HookError) Body() []byte {
-	return herr.body
-}
-
-func (herr HookError) Error() string {
-	return herr.error.Error()
-}

cmd/tusd/cli/hooks/http.go

@@ -8,8 +8,6 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/tus/tusd/pkg/handler"
-
 	"github.com/sethgrid/pester"
 )
 
@@ -18,35 +16,11 @@ type HttpHook struct {
 	MaxRetries     int
 	Backoff        int
 	ForwardHeaders []string
+
+	client *pester.Client
 }
 
-func (_ HttpHook) Setup() error {
+func (h *HttpHook) Setup() error {
-	return nil
-}
-
-func (h HttpHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput bool) ([]byte, int, error) {
-	jsonInfo, err := json.Marshal(info)
-	if err != nil {
-		return nil, 0, err
-	}
-
-	req, err := http.NewRequest("POST", h.Endpoint, bytes.NewBuffer(jsonInfo))
-	if err != nil {
-		return nil, 0, err
-	}
-
-	for _, k := range h.ForwardHeaders {
-		// Lookup the Canonicalised version of the specified header
-		if vals, ok := info.HTTPRequest.Header[http.CanonicalHeaderKey(k)]; ok {
-			// but set the case specified by the user
-			req.Header[k] = vals
-		}
-	}
-
-	req.Header.Set("Hook-Name", string(typ))
-	req.Header.Set("Content-Type", "application/json")
-
-	// TODO: Can we initialize this in Setup()?
 	// Use linear backoff strategy with the user defined values.
 	client := pester.New()
 	client.KeepLog = true
@@ -55,24 +29,51 @@ func (h HttpHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput
 		return time.Duration(h.Backoff) * time.Second
 	}
 
-	resp, err := client.Do(req)
+	h.client = client
+
+	return nil
+}
+
+func (h HttpHook) InvokeHook(hookReq HookRequest) (hookRes HookResponse, err error) {
+	jsonInfo, err := json.Marshal(hookReq)
 	if err != nil {
-		return nil, 0, err
+		return hookRes, err
 	}
-	defer resp.Body.Close()
 
-	body, err := ioutil.ReadAll(resp.Body)
+	httpReq, err := http.NewRequest("POST", h.Endpoint, bytes.NewBuffer(jsonInfo))
 	if err != nil {
-		return nil, 0, err
+		return hookRes, err
 	}
 
-	if resp.StatusCode >= http.StatusBadRequest {
+	for _, k := range h.ForwardHeaders {
-		return body, resp.StatusCode, NewHookError(fmt.Errorf("endpoint returned: %s", resp.Status), resp.StatusCode, body)
+		// Lookup the Canonicalised version of the specified header
+		if vals, ok := hookReq.Event.HTTPRequest.Header[http.CanonicalHeaderKey(k)]; ok {
+			// but set the case specified by the user
+			httpReq.Header[k] = vals
+		}
 	}
 
-	if captureOutput {
+	httpReq.Header.Set("Content-Type", "application/json")
-		return body, resp.StatusCode, err
+
+	httpRes, err := h.client.Do(httpReq)
+	if err != nil {
+		return hookRes, err
+	}
+	defer httpRes.Body.Close()
+
+	httpBody, err := ioutil.ReadAll(httpRes.Body)
+	if err != nil {
+		return hookRes, err
 	}
 
-	return nil, resp.StatusCode, err
+	// Report an error, if the response has a non-2XX status code
+	if httpRes.StatusCode < http.StatusOK || httpRes.StatusCode >= http.StatusMultipleChoices {
+		return hookRes, fmt.Errorf("unexpected response code from hook endpoint (%d): %s", httpRes.StatusCode, string(httpBody))
+	}
+
+	if err = json.Unmarshal(httpBody, &hookRes); err != nil {
+		return hookRes, fmt.Errorf("failed to parse hook response: %w", err)
+	}
+
+	return hookRes, nil
 }

cmd/tusd/cli/hooks/plugin.go

@@ -1,69 +1,122 @@
 package hooks
 
 import (
-	"fmt"
+	"log"
-	"plugin"
+	"net/rpc"
+	"os"
+	"os/exec"
 
-	"github.com/tus/tusd/pkg/handler"
+	"github.com/hashicorp/go-plugin"
 )
 
-type PluginHookHandler interface {
+// TODO: When the tusd process stops, the plugin does not get properly killed
-	PreCreate(info handler.HookEvent) error
+// and lives on as a zombie process.
-	PostCreate(info handler.HookEvent) error
-	PostReceive(info handler.HookEvent) error
-	PostFinish(info handler.HookEvent) error
-	PostTerminate(info handler.HookEvent) error
-	PreFinish(info handler.HookEvent) error
-}
 
 type PluginHook struct {
 	Path string
 
-	handler PluginHookHandler
+	handlerImpl HookHandler
 }
 
 func (h *PluginHook) Setup() error {
-	p, err := plugin.Open(h.Path)
+	// We're a host! Start by launching the plugin process.
+	client := plugin.NewClient(&plugin.ClientConfig{
+		HandshakeConfig: handshakeConfig,
+		Plugins:         pluginMap,
+		Cmd:             exec.Command(h.Path),
+		SyncStdout:      os.Stdout,
+		SyncStderr:      os.Stderr,
+		//Logger:          logger,
+	})
+	//defer client.Kill()
+
+	// Connect via RPC
+	rpcClient, err := client.Client()
 	if err != nil {
+		log.Fatal(err)
+	}
+
+	// Request the plugin
+	raw, err := rpcClient.Dispense("hookHandler")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// We should have a HookHandler now! This feels like a normal interface
+	// implementation but is in fact over an RPC connection.
+	h.handlerImpl = raw.(HookHandler)
+
+	return h.handlerImpl.Setup()
+}
+
+func (h *PluginHook) InvokeHook(req HookRequest) (HookResponse, error) {
+	return h.handlerImpl.InvokeHook(req)
+}
+
+// handshakeConfigs are used to just do a basic handshake between
+// a plugin and host. If the handshake fails, a user friendly error is shown.
+// This prevents users from executing bad plugins or executing a plugin
+// directory. It is a UX feature, not a security feature.
+var handshakeConfig = plugin.HandshakeConfig{
+	ProtocolVersion:  1,
+	MagicCookieKey:   "TUSD_PLUGIN",
+	MagicCookieValue: "yes",
+}
+
+// pluginMap is the map of plugins we can dispense.
+var pluginMap = map[string]plugin.Plugin{
+	"hookHandler": &HookHandlerPlugin{},
+}
+
+// Here is an implementation that talks over RPC
+type HookHandlerRPC struct{ client *rpc.Client }
+
+func (g *HookHandlerRPC) Setup() error {
+	var res interface{}
+	err := g.client.Call("Plugin.Setup", new(interface{}), &res)
 	return err
 }
 
-	symbol, err := p.Lookup("TusdHookHandler")
+func (g *HookHandlerRPC) InvokeHook(req HookRequest) (res HookResponse, err error) {
-	if err != nil {
+	err = g.client.Call("Plugin.InvokeHook", req, &res)
+	return res, err
+}
+
+// Here is the RPC server that HookHandlerRPC talks to, conforming to
+// the requirements of net/rpc
+type HookHandlerRPCServer struct {
+	// This is the real implementation
+	Impl HookHandler
+}
+
+func (s *HookHandlerRPCServer) Setup(args interface{}, resp *interface{}) error {
+	return s.Impl.Setup()
+}
+
+func (s *HookHandlerRPCServer) InvokeHook(args HookRequest, resp *HookResponse) (err error) {
+	*resp, err = s.Impl.InvokeHook(args)
 	return err
 }
 
-	handler, ok := symbol.(*PluginHookHandler)
+// This is the implementation of plugin.Plugin so we can serve/consume this
-	if !ok {
+//
-		return fmt.Errorf("hooks: could not cast TusdHookHandler from %s into PluginHookHandler interface", h.Path)
+// This has two methods: Server must return an RPC server for this plugin
+// type. We construct a HookHandlerRPCServer for this.
+//
+// Client must return an implementation of our interface that communicates
+// over an RPC client. We return HookHandlerRPC for this.
+//
+// Ignore MuxBroker. That is used to create more multiplexed streams on our
+// plugin connection and is a more advanced use case.
+type HookHandlerPlugin struct {
+	// Impl Injection
+	Impl HookHandler
 }
 
-	h.handler = *handler
+func (p *HookHandlerPlugin) Server(*plugin.MuxBroker) (interface{}, error) {
-	return nil
+	return &HookHandlerRPCServer{Impl: p.Impl}, nil
 }
 
-func (h PluginHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput bool) ([]byte, int, error) {
+func (HookHandlerPlugin) Client(b *plugin.MuxBroker, c *rpc.Client) (interface{}, error) {
-	var err error
+	return &HookHandlerRPC{client: c}, nil
-	switch typ {
-	case HookPostFinish:
-		err = h.handler.PostFinish(info)
-	case HookPostTerminate:
-		err = h.handler.PostTerminate(info)
-	case HookPostReceive:
-		err = h.handler.PostReceive(info)
-	case HookPostCreate:
-		err = h.handler.PostCreate(info)
-	case HookPreCreate:
-		err = h.handler.PreCreate(info)
-	case HookPreFinish:
-		err = h.handler.PreFinish(info)
-	default:
-		err = fmt.Errorf("hooks: unknown hook named %s", typ)
-	}
-
-	if err != nil {
-		return nil, 1, err
-	}
-
-	return nil, 0, nil
 }

cmd/tusd/cli/hooks/proto/v1/hook.proto

@@ -1,77 +0,0 @@
-// If this file gets changed, you must recompile the generate package in pkg/proto.
-// To do this, install the Go protobuf toolchain as mentioned in
-// https://github.com/golang/protobuf#installation.
-// Then use following command to recompile it with gRPC support:
-//   protoc --go_out=plugins=grpc:../../../../../pkg/proto/ v1/hook.proto
-// In addition, it may be necessary to update the protobuf or gRPC dependencies as well.
-
-syntax = "proto3";
-package v1;
-
-import "google/protobuf/any.proto";
-
-// Uploaded data
-message Upload {
-	// Unique integer identifier of the uploaded file
-	string id = 1;
-	// Total file size in bytes specified in the NewUpload call
-	int64 Size = 2; 
-	// Indicates whether the total file size is deferred until later
-	bool SizeIsDeferred = 3;
-	// Offset in bytes (zero-based)
-	int64 Offset = 4;
-	map<string, string> metaData = 5;
-	// Indicates that this is a partial upload which will later be used to form
-	// a final upload by concatenation. Partial uploads should not be processed
-	// when they are finished since they are only incomplete chunks of files.
-	bool isPartial = 6; 
-	// Indicates that this is a final upload
-	bool isFinal = 7; 
-	// If the upload is a final one (see IsFinal) this will be a non-empty
-	// ordered slice containing the ids of the uploads of which the final upload
-	// will consist after concatenation.
-	repeated string partialUploads = 8;
-	// Storage contains information about where the data storage saves the upload,
-	// for example a file path. The available values vary depending on what data
-	// store is used. This map may also be nil.
-	map <string, string> storage = 9;
-}
-
-message HTTPRequest {
-	// Method is the HTTP method, e.g. POST or PATCH
-	string method = 1;
-	// URI is the full HTTP request URI, e.g. /files/fooo
-	string uri = 2;
-	// RemoteAddr contains the network address that sent the request
-	string remoteAddr = 3; 
-}
-
-// Hook's data
-message Hook {
-	// Upload contains information about the upload that caused this hook
-	// to be fired.
-	Upload upload = 1;
-	// HTTPRequest contains details about the HTTP request that reached
-	// tusd.
-	HTTPRequest httpRequest = 2;
-	// The hook name
-	string name = 3;
-}
-
-// Request data to send hook
-message SendRequest {
-  // The hook data
-  Hook hook = 1;
-}
-
-// Response that contains data for sended hook
-message SendResponse {
-  // The response of the hook.
-  google.protobuf.Any response = 1;
-}
-
-// The hook service definition.
-service HookService {
-  // Sends a hook
-  rpc Send (SendRequest) returns (SendResponse) {}
-}

cmd/tusd/cli/hooks/proto/v2/hook.proto

@@ -0,0 +1,116 @@
+// If this file gets changed, you must recompile the generate package in pkg/proto.
+// To do this, install the Go protobuf toolchain as mentioned in
+// https://github.com/golang/protobuf#installation.
+// Then use following command to recompile it with gRPC support:
+//   protoc --go_out=plugins=grpc:../../../../../pkg/proto/ v2/hook.proto
+// In addition, it may be necessary to update the protobuf or gRPC dependencies as well.
+
+syntax = "proto3";
+package v2;
+
+// HookRequest contains the information about the hook type, the involved upload,
+// and causing HTTP request.
+message HookRequest {
+	// Type is the name of the hook.
+	string type = 1;
+	
+	// Event contains the involved upload and causing HTTP request.
+	Event event = 2;
+}
+
+// Event represents an event from tusd which can be handled by the application.
+message Event {
+	// Upload contains information about the upload that caused this hook
+	// to be fired.
+	FileInfo upload = 1;
+
+	// HTTPRequest contains details about the HTTP request that reached
+	// tusd.
+	HTTPRequest httpRequest = 2;
+}
+
+// FileInfo contains information about a single upload resource.
+message FileInfo {
+	// ID is the unique identifier of the upload resource.
+	string id = 1;
+	// Total file size in bytes specified in the NewUpload call
+	int64 size = 2; 
+	// Indicates whether the total file size is deferred until later
+	bool sizeIsDeferred = 3;
+	// Offset in bytes (zero-based)
+	int64 offset = 4;
+	map<string, string> metaData = 5;
+	// Indicates that this is a partial upload which will later be used to form
+	// a final upload by concatenation. Partial uploads should not be processed
+	// when they are finished since they are only incomplete chunks of files.
+	bool isPartial = 6; 
+	// Indicates that this is a final upload
+	bool isFinal = 7; 
+	// If the upload is a final one (see IsFinal) this will be a non-empty
+	// ordered slice containing the ids of the uploads of which the final upload
+	// will consist after concatenation.
+	repeated string partialUploads = 8;
+	// Storage contains information about where the data storage saves the upload,
+	// for example a file path. The available values vary depending on what data
+	// store is used. This map may also be nil.
+	map <string, string> storage = 9;
+}
+
+// HTTPRequest contains basic details of an incoming HTTP request.
+message HTTPRequest {
+	// Method is the HTTP method, e.g. POST or PATCH.
+	string method = 1;
+	// URI is the full HTTP request URI, e.g. /files/fooo.
+	string uri = 2;
+	// RemoteAddr contains the network address that sent the request.
+	string remoteAddr = 3; 
+	// Header contains all HTTP headers as present in the HTTP request.
+	map <string, string> header = 4;
+}
+
+// HookResponse is the response after a hook is executed.
+message HookResponse {
+// HTTPResponse's fields can be filled to modify the HTTP response.
+	// This is only possible for pre-create, pre-finish and post-receive hooks.
+	// For other hooks this value is ignored.
+	// If multiple hooks modify the HTTP response, a later hook may overwrite the
+	// modified values from a previous hook (e.g. if multiple post-receive hooks
+	// are executed).
+	// Example usages: Send an error to the client if RejectUpload/StopUpload are
+	// set in the pre-create/post-receive hook. Send more information to the client
+	// in the pre-finish hook.
+	HTTPResponse httpResponse = 1;
+
+	// RejectUpload will cause the upload to be rejected and not be created during
+	// POST request. This value is only respected for pre-create hooks. For other hooks,
+	// it is ignored. Use the HTTPResponse field to send details about the rejection
+	// to the client.
+	bool rejectUpload = 2;
+
+	// StopUpload will cause the upload to be stopped during a PATCH request.
+	// This value is only respected for post-receive hooks. For other hooks,
+	// it is ignored. Use the HTTPResponse field to send details about the stop
+	// to the client.
+	bool stopUpload = 3;
+}
+
+// HTTPResponse contains basic details of an outgoing HTTP response.
+message HTTPResponse {
+	// StatusCode is status code, e.g. 200 or 400.
+	int64 statusCode = 1;
+	// Headers contains additional HTTP headers for the response.
+	map <string, string> headers = 2;
+	// Body is the response body.
+	string body = 3;
+}
+
+
+// The hook service definition.
+service HookHandler {
+  // InvokeHook is invoked for every hook that is executed. HookRequest contains the
+	// corresponding information about the hook type, the involved upload, and
+	// causing HTTP request.
+	// The return value HookResponse allows to stop or reject an upload, as well as modifying
+	// the HTTP response. See the documentation for HookResponse for more details.
+  rpc InvokeHook (HookRequest) returns (HookResponse) {}
+}

docs/hooks.md

@@ -1,5 +1,7 @@
 # Hooks
 
+TODO: Update with new details
+
 When integrating tusd into an application, it is important to establish a communication channel between the two components. The tusd binary accomplishes this by providing a system which triggers actions when certain events happen, such as an upload being created or finished. This simple-but-powerful system enables uses ranging from logging over validation and authorization to processing the uploaded files.
 
 When a specific action happens during an upload (pre-create, post-receive, post-finish, or post-terminate), the hook system enables tusd to fire off a specific event. Tusd provides two ways of doing this:
@@ -211,9 +213,9 @@ $ # Retrying 5 times with a 2 second backoff
 $ tusd --hooks-http http://localhost:8081/write --hooks-http-retry 5 --hooks-http-backoff 2
 ```
 
-## GRPC Hooks
+## gRPC Hooks
 
-GRPC Hooks are the third type of hooks supported by tusd. Like the others hooks, it is disabled by default. To enable it, pass the `--hooks-grpc` option to the tusd binary. The flag's value will be a gRPC endpoint, which the tusd binary will be sent to:
+gRPC Hooks are the third type of hooks supported by tusd. Like the others hooks, it is disabled by default. To enable it, pass the `--hooks-grpc` option to the tusd binary. The flag's value will be a gRPC endpoint, which the tusd binary will be sent to:
 
 ```bash
 $ tusd --hooks-grpc localhost:8080

docs/minio.txt

@@ -0,0 +1,3 @@
+MINIO_ROOT_USER=AKIAIOSFODNN7EXAMPLE MINIO_ROOT_PASSWORD=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY ./minio server data
+
+AWS_ACCESS_KEY_ID=AKIAIOSFODNN7EXAMPLE AWS_SECRET_ACCESS_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY go run cmd/tusd/main.go -s3-bucket tusdtest.transloadit.com -s3-endpoint http://127.0.0.1:9000 -expose-pprof

examples/README.md

@@ -0,0 +1,11 @@
+# Examples
+
+This directory contains following examples:
+
+- `apache2.conf` is the recommended minimum configuration for an Apache2 proxy in front of tusd.
+- `nginx.conf` is the recommended minimum configuration for an Nginx proxy in front of tusd.
+- `server/` is an example of how to the tusd package embedded in your own Go application.
+- `hooks/file/` are Bash scripts for file hook implementations.
+- `hooks/http/` is a Python HTTP server as the HTTP hook implementation.
+- `hooks/grpc/` is a Python gRPC server as the gRPC hook implementation.
+- `hooks/plugin/` is a Go plugin usable with the plugin hooks.

examples/hooks/file/post-create

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from stdout and output debug messages.
+
+id="$TUS_ID"
+size="$TUS_SIZE"
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+echo "Upload created with ID ${id} and size ${size}" >&2
+cat /dev/stdin | jq . >&2

examples/hooks/file/post-finish

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from environment variables, stdin, and output debug messages.
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+echo "Upload $TUS_ID ($TUS_SIZE bytes) finished" >&2
+cat /dev/stdin | jq . >&2

examples/hooks/file/post-receive

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from environment variables and output debug messages.
+
+id="$TUS_ID"
+offset="$TUS_OFFSET"
+size="$TUS_SIZE"
+progress=$((100 * $offset/$size))
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+echo "Upload ${id} is at ${progress}% (${offset}/${size})" >&2

examples/hooks/file/post-terminate

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from environment variables, stdin, and output debug messages.
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+echo "Upload $TUS_ID terminated" >&2
+cat /dev/stdin | jq . >&2

examples/hooks/file/pre-create

@@ -0,0 +1,37 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from stdout, output debug messages, and reject a new upload based
+# on custom constraints. Here, an upload will be rejected if the
+# filename metadata is missing. Remove the following `exit 0` line
+# to activate the constraint:
+exit 0
+
+hasFilename="$(cat /dev/stdin | jq '.Event.Upload.MetaData | has("filename")')"
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+echo "Filename exists: $hasFilename" >&2
+
+if [ "$hasFilename" == "false" ]; then
+
+  # If the condition is not met, output a JSON object on stdout,
+  # that instructs tusd to reject the upload and respond with a custom
+  # HTTP error response.
+  cat <<END
+  {
+    "RejectUpload": true,
+    "HTTPResponse": {
+      "StatusCode": 400,
+      "Body": "no filename provided"
+    }
+  }
+END
+
+  # It is important that the hook exits with code 0. Otherwise, tusd
+  # assumes the hook has failed and will print an error message about
+  # the hook failure.
+  exit 0
+fi

examples/hooks/file/pre-finish

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+# This example demonstrates how to read the hook event details
+# from stdin, and output debug messages.
+
+# We use >&2 to write debugging output to stderr. tusd
+# will forward these to its stderr. Any output from the
+# hook on stdout will be captured by tusd and interpreted
+# as a response.
+cat /dev/stdin | jq . >&2

examples/hooks/grpc/Makefile

@@ -0,0 +1,2 @@
+hook_pb2.py:
+	python -m grpc_tools.protoc --proto_path=../../../cmd/tusd/cli/hooks/proto/v2/ hook.proto --python_out=. --grpc_python_out=.

examples/hooks/grpc/hook_pb2.py

@@ -0,0 +1,139 @@
+# -*- coding: utf-8 -*-
+# Generated by the protocol buffer compiler.  DO NOT EDIT!
+# source: hook.proto
+"""Generated protocol buffer code."""
+from google.protobuf import descriptor as _descriptor
+from google.protobuf import descriptor_pool as _descriptor_pool
+from google.protobuf import message as _message
+from google.protobuf import reflection as _reflection
+from google.protobuf import symbol_database as _symbol_database
+# @@protoc_insertion_point(imports)
+
+_sym_db = _symbol_database.Default()
+
+
+
+
+DESCRIPTOR = _descriptor_pool.Default().AddSerializedFile(b'\n\nhook.proto\x12\x02v2\"5\n\x0bHookRequest\x12\x0c\n\x04type\x18\x01 \x01(\t\x12\x18\n\x05\x65vent\x18\x02 \x01(\x0b\x32\t.v2.Event\"K\n\x05\x45vent\x12\x1c\n\x06upload\x18\x01 \x01(\x0b\x32\x0c.v2.FileInfo\x12$\n\x0bhttpRequest\x18\x02 \x01(\x0b\x32\x0f.v2.HTTPRequest\"\xc3\x02\n\x08\x46ileInfo\x12\n\n\x02id\x18\x01 \x01(\t\x12\x0c\n\x04size\x18\x02 \x01(\x03\x12\x16\n\x0esizeIsDeferred\x18\x03 \x01(\x08\x12\x0e\n\x06offset\x18\x04 \x01(\x03\x12,\n\x08metaData\x18\x05 \x03(\x0b\x32\x1a.v2.FileInfo.MetaDataEntry\x12\x11\n\tisPartial\x18\x06 \x01(\x08\x12\x0f\n\x07isFinal\x18\x07 \x01(\x08\x12\x16\n\x0epartialUploads\x18\x08 \x03(\t\x12*\n\x07storage\x18\t \x03(\x0b\x32\x19.v2.FileInfo.StorageEntry\x1a/\n\rMetaDataEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\t:\x02\x38\x01\x1a.\n\x0cStorageEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\t:\x02\x38\x01\"\x9a\x01\n\x0bHTTPRequest\x12\x0e\n\x06method\x18\x01 \x01(\t\x12\x0b\n\x03uri\x18\x02 \x01(\t\x12\x12\n\nremoteAddr\x18\x03 \x01(\t\x12+\n\x06header\x18\x04 \x03(\x0b\x32\x1b.v2.HTTPRequest.HeaderEntry\x1a-\n\x0bHeaderEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\t:\x02\x38\x01\"`\n\x0cHookResponse\x12&\n\x0chttpResponse\x18\x01 \x01(\x0b\x32\x10.v2.HTTPResponse\x12\x14\n\x0crejectUpload\x18\x02 \x01(\x08\x12\x12\n\nstopUpload\x18\x03 \x01(\x08\"\x90\x01\n\x0cHTTPResponse\x12\x12\n\nstatusCode\x18\x01 \x01(\x03\x12.\n\x07headers\x18\x02 \x03(\x0b\x32\x1d.v2.HTTPResponse.HeadersEntry\x12\x0c\n\x04\x62ody\x18\x03 \x01(\t\x1a.\n\x0cHeadersEntry\x12\x0b\n\x03key\x18\x01 \x01(\t\x12\r\n\x05value\x18\x02 \x01(\t:\x02\x38\x01\x32@\n\x0bHookHandler\x12\x31\n\nInvokeHook\x12\x0f.v2.HookRequest\x1a\x10.v2.HookResponse\"\x00\x62\x06proto3')
+
+
+
+_HOOKREQUEST = DESCRIPTOR.message_types_by_name['HookRequest']
+_EVENT = DESCRIPTOR.message_types_by_name['Event']
+_FILEINFO = DESCRIPTOR.message_types_by_name['FileInfo']
+_FILEINFO_METADATAENTRY = _FILEINFO.nested_types_by_name['MetaDataEntry']
+_FILEINFO_STORAGEENTRY = _FILEINFO.nested_types_by_name['StorageEntry']
+_HTTPREQUEST = DESCRIPTOR.message_types_by_name['HTTPRequest']
+_HTTPREQUEST_HEADERENTRY = _HTTPREQUEST.nested_types_by_name['HeaderEntry']
+_HOOKRESPONSE = DESCRIPTOR.message_types_by_name['HookResponse']
+_HTTPRESPONSE = DESCRIPTOR.message_types_by_name['HTTPResponse']
+_HTTPRESPONSE_HEADERSENTRY = _HTTPRESPONSE.nested_types_by_name['HeadersEntry']
+HookRequest = _reflection.GeneratedProtocolMessageType('HookRequest', (_message.Message,), {
+  'DESCRIPTOR' : _HOOKREQUEST,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.HookRequest)
+  })
+_sym_db.RegisterMessage(HookRequest)
+
+Event = _reflection.GeneratedProtocolMessageType('Event', (_message.Message,), {
+  'DESCRIPTOR' : _EVENT,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.Event)
+  })
+_sym_db.RegisterMessage(Event)
+
+FileInfo = _reflection.GeneratedProtocolMessageType('FileInfo', (_message.Message,), {
+
+  'MetaDataEntry' : _reflection.GeneratedProtocolMessageType('MetaDataEntry', (_message.Message,), {
+    'DESCRIPTOR' : _FILEINFO_METADATAENTRY,
+    '__module__' : 'hook_pb2'
+    # @@protoc_insertion_point(class_scope:v2.FileInfo.MetaDataEntry)
+    })
+  ,
+
+  'StorageEntry' : _reflection.GeneratedProtocolMessageType('StorageEntry', (_message.Message,), {
+    'DESCRIPTOR' : _FILEINFO_STORAGEENTRY,
+    '__module__' : 'hook_pb2'
+    # @@protoc_insertion_point(class_scope:v2.FileInfo.StorageEntry)
+    })
+  ,
+  'DESCRIPTOR' : _FILEINFO,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.FileInfo)
+  })
+_sym_db.RegisterMessage(FileInfo)
+_sym_db.RegisterMessage(FileInfo.MetaDataEntry)
+_sym_db.RegisterMessage(FileInfo.StorageEntry)
+
+HTTPRequest = _reflection.GeneratedProtocolMessageType('HTTPRequest', (_message.Message,), {
+
+  'HeaderEntry' : _reflection.GeneratedProtocolMessageType('HeaderEntry', (_message.Message,), {
+    'DESCRIPTOR' : _HTTPREQUEST_HEADERENTRY,
+    '__module__' : 'hook_pb2'
+    # @@protoc_insertion_point(class_scope:v2.HTTPRequest.HeaderEntry)
+    })
+  ,
+  'DESCRIPTOR' : _HTTPREQUEST,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.HTTPRequest)
+  })
+_sym_db.RegisterMessage(HTTPRequest)
+_sym_db.RegisterMessage(HTTPRequest.HeaderEntry)
+
+HookResponse = _reflection.GeneratedProtocolMessageType('HookResponse', (_message.Message,), {
+  'DESCRIPTOR' : _HOOKRESPONSE,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.HookResponse)
+  })
+_sym_db.RegisterMessage(HookResponse)
+
+HTTPResponse = _reflection.GeneratedProtocolMessageType('HTTPResponse', (_message.Message,), {
+
+  'HeadersEntry' : _reflection.GeneratedProtocolMessageType('HeadersEntry', (_message.Message,), {
+    'DESCRIPTOR' : _HTTPRESPONSE_HEADERSENTRY,
+    '__module__' : 'hook_pb2'
+    # @@protoc_insertion_point(class_scope:v2.HTTPResponse.HeadersEntry)
+    })
+  ,
+  'DESCRIPTOR' : _HTTPRESPONSE,
+  '__module__' : 'hook_pb2'
+  # @@protoc_insertion_point(class_scope:v2.HTTPResponse)
+  })
+_sym_db.RegisterMessage(HTTPResponse)
+_sym_db.RegisterMessage(HTTPResponse.HeadersEntry)
+
+_HOOKHANDLER = DESCRIPTOR.services_by_name['HookHandler']
+if _descriptor._USE_C_DESCRIPTORS == False:
+
+  DESCRIPTOR._options = None
+  _FILEINFO_METADATAENTRY._options = None
+  _FILEINFO_METADATAENTRY._serialized_options = b'8\001'
+  _FILEINFO_STORAGEENTRY._options = None
+  _FILEINFO_STORAGEENTRY._serialized_options = b'8\001'
+  _HTTPREQUEST_HEADERENTRY._options = None
+  _HTTPREQUEST_HEADERENTRY._serialized_options = b'8\001'
+  _HTTPRESPONSE_HEADERSENTRY._options = None
+  _HTTPRESPONSE_HEADERSENTRY._serialized_options = b'8\001'
+  _HOOKREQUEST._serialized_start=18
+  _HOOKREQUEST._serialized_end=71
+  _EVENT._serialized_start=73
+  _EVENT._serialized_end=148
+  _FILEINFO._serialized_start=151
+  _FILEINFO._serialized_end=474
+  _FILEINFO_METADATAENTRY._serialized_start=379
+  _FILEINFO_METADATAENTRY._serialized_end=426
+  _FILEINFO_STORAGEENTRY._serialized_start=428
+  _FILEINFO_STORAGEENTRY._serialized_end=474
+  _HTTPREQUEST._serialized_start=477
+  _HTTPREQUEST._serialized_end=631
+  _HTTPREQUEST_HEADERENTRY._serialized_start=586
+  _HTTPREQUEST_HEADERENTRY._serialized_end=631
+  _HOOKRESPONSE._serialized_start=633
+  _HOOKRESPONSE._serialized_end=729
+  _HTTPRESPONSE._serialized_start=732
+  _HTTPRESPONSE._serialized_end=876
+  _HTTPRESPONSE_HEADERSENTRY._serialized_start=830
+  _HTTPRESPONSE_HEADERSENTRY._serialized_end=876
+  _HOOKHANDLER._serialized_start=878
+  _HOOKHANDLER._serialized_end=942
+# @@protoc_insertion_point(module_scope)

examples/hooks/grpc/hook_pb2_grpc.py

@@ -0,0 +1,70 @@
+# Generated by the gRPC Python protocol compiler plugin. DO NOT EDIT!
+"""Client and server classes corresponding to protobuf-defined services."""
+import grpc
+
+import hook_pb2 as hook__pb2
+
+
+class HookHandlerStub(object):
+    """The hook service definition.
+    """
+
+    def __init__(self, channel):
+        """Constructor.
+
+        Args:
+            channel: A grpc.Channel.
+        """
+        self.InvokeHook = channel.unary_unary(
+                '/v2.HookHandler/InvokeHook',
+                request_serializer=hook__pb2.HookRequest.SerializeToString,
+                response_deserializer=hook__pb2.HookResponse.FromString,
+                )
+
+
+class HookHandlerServicer(object):
+    """The hook service definition.
+    """
+
+    def InvokeHook(self, request, context):
+        """Sends a hook
+        """
+        context.set_code(grpc.StatusCode.UNIMPLEMENTED)
+        context.set_details('Method not implemented!')
+        raise NotImplementedError('Method not implemented!')
+
+
+def add_HookHandlerServicer_to_server(servicer, server):
+    rpc_method_handlers = {
+            'InvokeHook': grpc.unary_unary_rpc_method_handler(
+                    servicer.InvokeHook,
+                    request_deserializer=hook__pb2.HookRequest.FromString,
+                    response_serializer=hook__pb2.HookResponse.SerializeToString,
+            ),
+    }
+    generic_handler = grpc.method_handlers_generic_handler(
+            'v2.HookHandler', rpc_method_handlers)
+    server.add_generic_rpc_handlers((generic_handler,))
+
+
+ # This class is part of an EXPERIMENTAL API.
+class HookHandler(object):
+    """The hook service definition.
+    """
+
+    @staticmethod
+    def InvokeHook(request,
+            target,
+            options=(),
+            channel_credentials=None,
+            call_credentials=None,
+            insecure=False,
+            compression=None,
+            wait_for_ready=None,
+            timeout=None,
+            metadata=None):
+        return grpc.experimental.unary_unary(request, target, '/v2.HookHandler/InvokeHook',
+            hook__pb2.HookRequest.SerializeToString,
+            hook__pb2.HookResponse.FromString,
+            options, channel_credentials,
+            insecure, call_credentials, compression, wait_for_ready, timeout, metadata)

examples/hooks/grpc/server.py

@@ -0,0 +1,57 @@
+import grpc
+from concurrent import futures
+import time
+import hook_pb2_grpc as pb2_grpc
+import hook_pb2 as pb2
+
+class HookHandler(pb2_grpc.HookHandlerServicer):
+
+    def __init__(self, *args, **kwargs):
+        pass
+
+    def InvokeHook(self, hook_request, context):
+        # Print data from hook request for debugging
+        print('Received hook request:')
+        print(hook_request)
+
+        # Prepare hook response structure
+        hook_response = pb2.HookResponse()
+
+        # Example: Use the pre-create hook to check if a filename has been supplied
+        # using metadata. If not, the upload is rejected with a custom HTTP response.
+        if hook_request.type == 'pre-create':
+            filename = hook_request.event.upload.metaData['filename']
+            if filename == "":
+                hook_response.rejectUpload = True
+                hook_response.httpResponse.statusCode = 400
+                hook_response.httpResponse.body = 'no filename provided'
+                hook_response.httpResponse.headers['X-Some-Header'] = 'yes'
+
+        # Example: Use the post-finish hook to print information about a completed upload,
+        # including its storage location.
+        if hook_request.type == 'post-finish':
+            id      = hook_request.event.upload.id
+            size    = hook_request.event.upload.size
+            storage = hook_request.event.upload.storage
+
+            print(f'Upload {id} ({size} bytes) is finished. Find the file at:')
+            print(storage)
+
+        # Print data of hook response for debugging
+        print('Responding with hook response:')
+        print(hook_response)
+        print('------')
+        print('')
+
+        # Return the hook response to send back to tusd
+        return hook_response
+
+def serve():
+    server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
+    pb2_grpc.add_HookHandlerServicer_to_server(HookHandler(), server)
+    server.add_insecure_port('[::]:8000')
+    server.start()
+    server.wait_for_termination()
+
+if __name__ == '__main__':
+    serve()

examples/hooks/http/server.py

@@ -0,0 +1,65 @@
+from http.server import HTTPServer, BaseHTTPRequestHandler
+from io import BytesIO
+
+import json
+
+class HTTPHookHandler(BaseHTTPRequestHandler):
+
+    def do_GET(self):
+        self.send_response(200)
+        self.end_headers()
+        self.wfile.write(b'Hello! This server only responds to POST requests')
+
+    def do_POST(self):
+        # Read entire body as JSON object
+        content_length = int(self.headers['Content-Length'])
+        request_body = self.rfile.read(content_length)
+        hook_request = json.loads(request_body)
+
+        # Print data from hook request for debugging
+        print('Received hook request:')
+        print(hook_request)
+
+        # Prepare hook response structure
+        hook_response = {
+            'HTTPResponse': {
+                'Headers': {}
+            }
+        }
+
+        # Example: Use the pre-create hook to check if a filename has been supplied
+        # using metadata. If not, the upload is rejected with a custom HTTP response.
+        if hook_request['Type'] == 'pre-create':
+            metaData = hook_request['Event']['Upload']['MetaData']
+            if 'filename' not in metaData:
+                hook_response['RejectUpload'] = True
+                hook_response['HTTPResponse']['StatusCode'] = 400
+                hook_response['HTTPResponse']['Body'] = 'no filename provided'
+                hook_response['HTTPResponse']['Headers']['X-Some-Header'] = 'yes'
+
+        # Example: Use the post-finish hook to print information about a completed upload,
+        # including its storage location.
+        if hook_request['Type'] == 'post-finish':
+            id      = hook_request['Event']['Upload']['ID']
+            size    = hook_request['Event']['Upload']['Size']
+            storage = hook_request['Event']['Upload']['Storage']
+
+            print(f'Upload {id} ({size} bytes) is finished. Find the file at:')
+            print(storage)
+
+
+        # Print data of hook response for debugging
+        print('Responding with hook response:')
+        print(hook_response)
+        print('------')
+        print('')
+
+        # Send the data from the hook response as JSON output
+        response_body = json.dumps(hook_response)
+        self.send_response(200)
+        self.end_headers()
+        self.wfile.write(response_body.encode())
+
+
+httpd = HTTPServer(('localhost', 8000), HTTPHookHandler)
+httpd.serve_forever()

examples/hooks/plugin/Makefile

@@ -0,0 +1,2 @@
+hook_handler: hook_handler.go
+	go build -o hook_handler ./hook_handler.go

examples/hooks/plugin/hook_handler.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/go-plugin"
+	"github.com/tus/tusd/cmd/tusd/cli/hooks"
+)
+
+// Here is the implementation of our hook handler
+type MyHookHandler struct {
+	logger hclog.Logger
+}
+
+// Setup is called once the plugin has been loaded by tusd.
+func (g *MyHookHandler) Setup() error {
+	// Use the log package or the g.logger field to write debug messages.
+	// Do not write to stdout directly, as this is used for communication between
+	// tusd and the plugin.
+	log.Println("MyHookHandler.Setup is invoked")
+	return nil
+}
+
+// InvokeHook is called for every hook that tusd fires.
+func (g *MyHookHandler) InvokeHook(req hooks.HookRequest) (res hooks.HookResponse, err error) {
+	log.Println("MyHookHandler.InvokeHook is invoked")
+
+	// Prepare hook response structure
+	res.HTTPResponse.Headers = make(map[string]string)
+
+	// Example: Use the pre-create hook to check if a filename has been supplied
+	// using metadata. If not, the upload is rejected with a custom HTTP response.
+
+	if req.Type == hooks.HookPreCreate {
+		if _, ok := req.Event.Upload.MetaData["filename"]; !ok {
+			res.RejectUpload = true
+			res.HTTPResponse.StatusCode = 400
+			res.HTTPResponse.Body = "no filename provided"
+			res.HTTPResponse.Headers["X-Some-Header"] = "yes"
+		}
+	}
+
+	// Example: Use the post-finish hook to print information about a completed upload,
+	// including its storage location.
+	if req.Type == hooks.HookPreFinish {
+		id := req.Event.Upload.ID
+		size := req.Event.Upload.Size
+		storage := req.Event.Upload.Storage
+
+		log.Printf("Upload %s (%d bytes) is finished. Find the file at:\n", id, size)
+		log.Println(storage)
+
+	}
+
+	// Return the hook response to tusd.
+	return res, nil
+}
+
+// handshakeConfigs are used to just do a basic handshake between
+// a plugin and tusd. If the handshake fails, a user friendly error is shown.
+// This prevents users from executing bad plugins or executing a plugin
+// directory. It is a UX feature, not a security feature.
+var handshakeConfig = plugin.HandshakeConfig{
+	ProtocolVersion:  1,
+	MagicCookieKey:   "TUSD_PLUGIN",
+	MagicCookieValue: "yes",
+}
+
+func main() {
+	// 1. Initialize our handler.
+	myHandler := &MyHookHandler{}
+
+	// 2. Construct the plugin map. The key must be "hookHandler".
+	var pluginMap = map[string]plugin.Plugin{
+		"hookHandler": &hooks.HookHandlerPlugin{Impl: myHandler},
+	}
+
+	// 3. Expose the plugin to tusd.
+	plugin.Serve(&plugin.ServeConfig{
+		HandshakeConfig: handshakeConfig,
+		Plugins:         pluginMap,
+	})
+
+	fmt.Println("DOONE")
+}

examples/hooks/post-create

@@ -1,8 +0,0 @@
-#!/bin/sh
-
-id="$TUS_ID"
-offset="$TUS_OFFSET"
-size="$TUS_SIZE"
-
-echo "Upload created with ID ${id} and size ${size}"
-cat /dev/stdin | jq .

examples/hooks/post-finish

@@ -1,4 +0,0 @@
-#!/bin/sh
-
-echo "Upload $TUS_ID ($TUS_SIZE bytes) finished"
-cat /dev/stdin | jq .

examples/hooks/post-receive

@@ -1,8 +0,0 @@
-#!/bin/sh
-
-id="$TUS_ID"
-offset="$TUS_OFFSET"
-size="$TUS_SIZE"
-progress=$((100 * $offset/$size))
-
-echo "Upload ${id} is at ${progress}% (${offset}/${size})"

examples/hooks/post-terminate

@@ -1,4 +0,0 @@
-#!/bin/sh
-
-echo "Upload $TUS_ID terminated"
-cat /dev/stdin | jq .

examples/hooks/pre-create

@@ -1,7 +0,0 @@
-#!/bin/sh
-
-filename=$(cat /dev/stdin | jq .Upload.MetaData.filename)
-if [ -z "$filename" ]; then
-  echo "Error: no filename provided"
-  exit 1
-fi

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/golang/mock v1.6.0
 	github.com/golang/protobuf v1.5.2
 	github.com/grpc-ecosystem/go-grpc-middleware v1.3.0
+	github.com/hashicorp/go-plugin v1.4.3 // indirect
 	github.com/prometheus/client_golang v1.12.1
 	github.com/sethgrid/pester v0.0.0-20190127155807-68a33a018ad0
 	github.com/stretchr/testify v1.7.0

go.sum

@@ -118,6 +118,8 @@ github.com/envoyproxy/go-control-plane v0.9.9-0.20210217033140-668b12f5399d/go.m
 github.com/envoyproxy/go-control-plane v0.9.9-0.20210512163311-63b5d3c536b0/go.mod h1:hliV/p42l8fGbc6Y9bQ70uLwIvmJyVE5k4iMKlh8wCQ=
 github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.mod h1:AFq3mo9L8Lqqiid3OhADV3RfLJnjiw63cSpi+fDTRC0=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
+github.com/fatih/color v1.7.0 h1:DkWD4oS2D8LGGgTQ6IvwJJXSL5Vp2ffcQg58nFV38Ys=
+github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/form3tech-oss/jwt-go v3.2.2+incompatible h1:TcekIExNqud5crz4xD2pavyTgWiPvpYe4Xau31I0PRk=
 github.com/form3tech-oss/jwt-go v3.2.2+incompatible/go.mod h1:pbq4aXjuKjdthFRnoDwaVPLA+WlJuPGy+QneDUgJi2k=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=
@@ -219,10 +221,17 @@ github.com/grpc-ecosystem/go-grpc-middleware v1.3.0/go.mod h1:z0ButlSOZa5vEBq9m2
 github.com/grpc-ecosystem/grpc-gateway v1.16.0/go.mod h1:BDjrQk3hbvj6Nolgz8mAMFbcEtjT1g+wF4CSlocrBnw=
 github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542 h1:2VTzZjLZBgl62/EtslCrtky5vbi9dd7HrQPQIx6wqiw=
 github.com/h2non/parth v0.0.0-20190131123155-b4df798d6542/go.mod h1:Ow0tF8D4Kplbc8s8sSb3V2oUCygFHVp8gC3Dn6U4MNI=
+github.com/hashicorp/go-hclog v0.14.1 h1:nQcJDQwIAGnmoUWp8ubocEX40cCml/17YkF6csQLReU=
+github.com/hashicorp/go-hclog v0.14.1/go.mod h1:whpDNt7SSdeAju8AWKIWsul05p54N/39EeqMAyrmvFQ=
+github.com/hashicorp/go-plugin v1.4.3 h1:DXmvivbWD5qdiBts9TpBC7BYL1Aia5sxbRgQB+v6UZM=
+github.com/hashicorp/go-plugin v1.4.3/go.mod h1:5fGEH17QVwTTcR0zV7yhDPLLmFX9YSZ38b18Udy6vYQ=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb h1:b5rjCoWHc7eqmAS4/qyk21ZsHyb6Mxv/jykxvNTkU4M=
+github.com/hashicorp/yamux v0.0.0-20180604194846-3520598351bb/go.mod h1:+NfK9FKeTrX5uv1uIXGdwYDTeHna2qgaIlx54MXqjAM=
 github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/ianlancetaylor/demangle v0.0.0-20200824232613-28f6c0f3b639/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
+github.com/jhump/protoreflect v1.6.0/go.mod h1:eaTn3RZAmMBcV0fifFvlm6VHNz3wSkYyXYWUh7ymB74=
 github.com/jmespath/go-jmespath v0.4.0 h1:BEgLn5cpjn8UN1mAw4NjwDrS35OdebyEtFe+9YPoQUg=
 github.com/jmespath/go-jmespath v0.4.0/go.mod h1:T8mJZnbsbmF+m6zOOFylbeCJqk5+pHWvzYPziyZiYoo=
 github.com/jmespath/go-jmespath/internal/testify v1.5.1 h1:shLQSRRSCCPj3f2gpwzGwWFoC7ycTf1rcQZHOlsJ6N8=
@@ -247,10 +256,17 @@ github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfn
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
 github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
 github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
+github.com/mattn/go-colorable v0.1.4 h1:snbPLB8fVfU9iwbbo30TPtbLRzwWu6aJS6Xh4eaaviA=
+github.com/mattn/go-colorable v0.1.4/go.mod h1:U0ppj6V5qS13XJ6of8GYAs25YV2eR4EVcfRqFIhoBtE=
 github.com/mattn/go-ieproxy v0.0.1 h1:qiyop7gCflfhwCzGyeT0gro3sF9AIg9HU98JORTkqfI=
 github.com/mattn/go-ieproxy v0.0.1/go.mod h1:pYabZ6IHcRpFh7vIaLfK7rdcWgFEb3SFJ6/gNWuh88E=
+github.com/mattn/go-isatty v0.0.8/go.mod h1:Iq45c/XA43vh69/j3iqttzPXn0bhXyGjM0Hdxcsrc5s=
+github.com/mattn/go-isatty v0.0.10 h1:qxFzApOv4WsAL965uUPIsXzAKCZxN2p9UqdhFS4ZW10=
+github.com/mattn/go-isatty v0.0.10/go.mod h1:qgIWMr58cqv1PHHyhnkY9lrL7etaEgOFcMEpPG5Rm84=
 github.com/matttproud/golang_protobuf_extensions v1.0.1 h1:4hp9jkHxhMHkqkrB3Ix0jegS5sx/RkqARlsWZ6pIwiU=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
+github.com/mitchellh/go-testing-interface v0.0.0-20171004221916-a61a99592b77 h1:7GoSOOW2jpsfkntVKaS2rAr1TJqfcxotyaUcuxoZSzg=
+github.com/mitchellh/go-testing-interface v0.0.0-20171004221916-a61a99592b77/go.mod h1:kRemZodwjscx+RGhAo8eIhFbs2+BFgRtFPeD/KE+zxI=
 github.com/modern-go/concurrent v0.0.0-20180228061459-e0a39a4cb421/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJC0mAP4ikYIbvyc7fijjWJddQyLn8Ig3JB5CqoB9Q=
 github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
@@ -260,6 +276,8 @@ github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRW
 github.com/mwitkow/go-conntrack v0.0.0-20190716064945-2f068394615f/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/nbio/st v0.0.0-20140626010706-e9e8d9816f32 h1:W6apQkHrMkS0Muv8G/TipAy/FJl/rCYT0+EuS8+Z0z4=
 github.com/nbio/st v0.0.0-20140626010706-e9e8d9816f32/go.mod h1:9wM+0iRr9ahx58uYLpLIr5fm8diHn0JbqRycJi6w0Ms=
+github.com/oklog/run v1.0.0 h1:Ru7dDtJNOyC66gQ5dQmaCa0qIsAUFY3sFpK1Xk8igrw=
+github.com/oklog/run v1.0.0/go.mod h1:dlhp/R75TPv97u0XWUtDeV/lRKWPKSdTuV0TZvrmrQA=
 github.com/opentracing/opentracing-go v1.1.0/go.mod h1:UkNAQd3GIcIGf0SeVgPpRdFStlNbqXla1AfSYxPUl2o=
 github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
@@ -368,6 +386,7 @@ golang.org/x/mod v0.3.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.1/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
 golang.org/x/mod v0.4.2/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20180530234432-1e491301e022/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20180826012351-8a410e7b638d/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20181114220301-adae6a3d119a/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
@@ -443,6 +462,7 @@ golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5h
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190222072716-a9d3bda3a223/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190312061237-fead79001313/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -452,6 +472,7 @@ golang.org/x/sys v0.0.0-20190606165138-5da285871e9c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190624142023-c5567b49c5d0/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191001151750-bb3f8db39f24/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191008105621-543471e840be/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191112214154-59a1497f0cea/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191204072324-ce4227a45e2e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20191228213918-04cbcbbfeed8/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -617,6 +638,7 @@ google.golang.org/appengine v1.6.5/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCID
 google.golang.org/appengine v1.6.6/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
 google.golang.org/appengine v1.6.7 h1:FZR1q0exgwxzPzp/aF+VccGrSfxfPpkBqjIIEq3ru6c=
 google.golang.org/appengine v1.6.7/go.mod h1:8WjMMxjGQR8xUklV/ARdw2HLXBOI7O7uCIDZVag1xfc=
+google.golang.org/genproto v0.0.0-20170818010345-ee236bd376b0/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8/go.mod h1:JiN7NxoALGmiZfu7CAH4rXhgtRTLTxftemlI0sWmxmc=
 google.golang.org/genproto v0.0.0-20190307195333-5fe7a883aa19/go.mod h1:VzzqZJRnGkLBvHegQrXjBqPurQTc5/KpmUdxsrq26oE=
 google.golang.org/genproto v0.0.0-20190418145605-e7d98fc518a7/go.mod h1:VzzqZJRnGkLBvHegQrXjBqPurQTc5/KpmUdxsrq26oE=
@@ -677,6 +699,10 @@ google.golang.org/genproto v0.0.0-20210831024726-fe130286e0e2/go.mod h1:eFjDcFEc
 google.golang.org/genproto v0.0.0-20210903162649-d08c68adba83/go.mod h1:eFjDcFEctNawg4eG61bRv87N7iHBWyVhJu7u1kqDUXY=
 google.golang.org/genproto v0.0.0-20210909211513-a8c4777a87af/go.mod h1:eFjDcFEctNawg4eG61bRv87N7iHBWyVhJu7u1kqDUXY=
 google.golang.org/genproto v0.0.0-20210924002016-3dee208752a0/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211008145708-270636b82663/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/genproto v0.0.0-20211016002631-37fc39342514 h1:Rp1vYDPD4TdkMH5S/bZbopsGCsWhPcrLBUwOVhAQCxM=
+google.golang.org/genproto v0.0.0-20211016002631-37fc39342514/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
+google.golang.org/grpc v1.8.0/go.mod h1:yo6s7OP7yaDglbqo1J04qKzAhqBH6lvTonzMVmEdcZw=
 google.golang.org/genproto v0.0.0-20211118181313-81c1377c94b1/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211206160659-862468c7d6e0/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=
 google.golang.org/genproto v0.0.0-20211208223120-3a66f561d7aa/go.mod h1:5CzLGKJ67TSI2B9POpiiyGha0AjJvZIUgRMt1dSmuhc=

pkg/handler/config.go

@@ -41,14 +41,18 @@ type Config struct {
 	// response to POST requests.
 	RespectForwardedHeaders bool
 	// PreUploadCreateCallback will be invoked before a new upload is created, if the
-	// property is supplied. If the callback returns nil, the upload will be created.
+	// property is supplied. If the callback returns no error, the upload will be created
-	// Otherwise the HTTP request will be aborted. This can be used to implement
+	// and optional values from HTTPResponse will be contained in the HTTP response.
-	// validation of upload metadata etc.
+	// If the error is non-nil, the upload will not be created. This can be used to implement
-	PreUploadCreateCallback func(hook HookEvent) error
+	// validation of upload metadata etc. Furthermore, HTTPResponse will be ignored and
+	// the error value can contain values for the HTTP response.
+	PreUploadCreateCallback func(hook HookEvent) (HTTPResponse, error)
 	// PreFinishResponseCallback will be invoked after an upload is completed but before
-	// a response is returned to the client. Error responses from the callback will be passed
+	// a response is returned to the client. This can be used to implement post-processing validation.
-	// back to the client. This can be used to implement post-processing validation.
+	// If the callback returns no error, optional values from HTTPResponse will be contained in the HTTP response.
-	PreFinishResponseCallback func(hook HookEvent) error
+	// If the error is non-nil, the error will be forwarded to the client. Furthermore,
+	// HTTPResponse will be ignored and the error value can contain values for the HTTP response.
+	PreFinishResponseCallback func(hook HookEvent) (HTTPResponse, error)
 }
 
 func (config *Config) validate() error {

pkg/handler/datastore.go

@@ -7,7 +7,9 @@ import (
 
 type MetaData map[string]string
 
+// FileInfo contains information about a single upload resource.
 type FileInfo struct {
+	// ID is the unique identifier of the upload resource.
 	ID string
 	// Total file size in bytes specified in the NewUpload call
 	Size int64
@@ -41,6 +43,7 @@ type FileInfo struct {
 // more data. Furthermore, a response is sent to notify the client of the
 // interrupting and the upload is terminated (if supported by the data store),
 // so the upload cannot be resumed anymore.
+// TODO: Allow passing in a HTTP Response
 func (f FileInfo) StopUpload() {
 	if f.stopUpload != nil {
 		f.stopUpload()

pkg/handler/error.go

@@ -0,0 +1,32 @@
+package handler
+
+// Error represents an error with the intent to be sent in the HTTP
+// response to the client. Therefore, it also contains a HTTPResponse,
+// next to an error code and error message.
+type Error struct {
+	ErrorCode    string
+	Message      string
+	HTTPResponse HTTPResponse
+}
+
+func (e Error) Error() string {
+	return e.ErrorCode + ": " + e.Message
+}
+
+// NewError constructs a new Error object with the given error code and message.
+// The corresponding HTTP response will have the provided status code
+// and a body consisting of the error details.
+// responses. See the net/http package for standardized status codes.
+func NewError(errCode string, message string, statusCode int) Error {
+	return Error{
+		ErrorCode: errCode,
+		Message:   message,
+		HTTPResponse: HTTPResponse{
+			StatusCode: statusCode,
+			Body:       errCode + ": " + message + "\n",
+			Headers: HTTPHeaders{
+				"Content-Type": "text/plain; charset=utf-8",
+			},
+		},
+	}
+}

pkg/handler/head_test.go

@@ -77,9 +77,7 @@ func TestHead(t *testing.T) {
 				"Tus-Resumable": "1.0.0",
 			},
 			Code:      http.StatusNotFound,
-			ResHeader: map[string]string{
+			ResHeader: map[string]string{},
-				"Content-Length": "0",
-			},
 		}).Run(handler, t)
 
 		if res.Body.String() != "" {

pkg/handler/hooks.go

@@ -0,0 +1,25 @@
+package handler
+
+import "net/http"
+
+// HookEvent represents an event from tusd which can be handled by the application.
+type HookEvent struct {
+	// Upload contains information about the upload that caused this hook
+	// to be fired.
+	Upload FileInfo
+	// HTTPRequest contains details about the HTTP request that reached
+	// tusd.
+	HTTPRequest HTTPRequest
+}
+
+func newHookEvent(info FileInfo, r *http.Request) HookEvent {
+	return HookEvent{
+		Upload: info,
+		HTTPRequest: HTTPRequest{
+			Method:     r.Method,
+			URI:        r.RequestURI,
+			RemoteAddr: r.RemoteAddr,
+			Header:     r.Header,
+		},
+	}
+}

pkg/handler/http.go

@@ -0,0 +1,80 @@
+package handler
+
+import (
+	"net/http"
+	"strconv"
+)
+
+// HTTPRequest contains basic details of an incoming HTTP request.
+type HTTPRequest struct {
+	// Method is the HTTP method, e.g. POST or PATCH.
+	Method string
+	// URI is the full HTTP request URI, e.g. /files/fooo.
+	URI string
+	// RemoteAddr contains the network address that sent the request.
+	RemoteAddr string
+	// Header contains all HTTP headers as present in the HTTP request.
+	Header http.Header
+}
+
+type HTTPHeaders map[string]string
+
+// HTTPResponse contains basic details of an outgoing HTTP response.
+type HTTPResponse struct {
+	// StatusCode is status code, e.g. 200 or 400.
+	StatusCode int
+	// Body is the response body.
+	Body string
+	// Headers contains additional HTTP headers for the response.
+	// TODO: Uniform naming with HTTPRequest.Header
+	Headers HTTPHeaders
+}
+
+// writeTo writes the HTTP response into w, as specified by the fields in resp.
+func (resp HTTPResponse) writeTo(w http.ResponseWriter) {
+	headers := w.Header()
+	for key, value := range resp.Headers {
+		headers.Set(key, value)
+	}
+
+	if len(resp.Body) > 0 {
+		headers.Set("Content-Length", strconv.Itoa(len(resp.Body)))
+	}
+
+	w.WriteHeader(resp.StatusCode)
+
+	if len(resp.Body) > 0 {
+		w.Write([]byte(resp.Body))
+	}
+}
+
+// MergeWith returns a copy of resp1, where non-default values from resp2 overwrite
+// values from resp1.
+func (resp1 HTTPResponse) MergeWith(resp2 HTTPResponse) HTTPResponse {
+	// Clone the response 1 and use it as a basis
+	newResp := resp1
+
+	// Take the status code and body from response 2 to
+	// overwrite values from response 1.
+	if resp2.StatusCode != 0 {
+		newResp.StatusCode = resp2.StatusCode
+	}
+
+	if len(resp2.Body) > 0 {
+		newResp.Body = resp2.Body
+	}
+
+	// For the headers, me must make a new map to avoid writing
+	// into the header map from response 1.
+	newResp.Headers = make(HTTPHeaders, len(resp1.Headers)+len(resp2.Headers))
+
+	for key, value := range resp1.Headers {
+		newResp.Headers[key] = value
+	}
+
+	for key, value := range resp2.Headers {
+		newResp.Headers[key] = value
+	}
+
+	return newResp
+}

pkg/handler/metrics.go

@@ -31,7 +31,7 @@ func (m Metrics) incRequestsTotal(method string) {
 
 // TODO: Rework to only store error code
 // incErrorsTotal increases the counter for this error atomically by one.
-func (m Metrics) incErrorsTotal(err HTTPError) {
+func (m Metrics) incErrorsTotal(err Error) {
 	ptr := m.ErrorsTotal.retrievePointerFor(err)
 	atomic.AddUint64(ptr, 1)
 }
@@ -95,10 +95,10 @@ func newErrorsTotalMap() *ErrorsTotalMap {
 
 // retrievePointerFor returns (after creating it if necessary) the pointer to
 // the counter for the error.
-func (e *ErrorsTotalMap) retrievePointerFor(err HTTPError) *uint64 {
+func (e *ErrorsTotalMap) retrievePointerFor(err Error) *uint64 {
 	serr := ErrorsTotalMapEntry{
-		ErrorCode:  err.ErrorCode(),
+		ErrorCode:  err.ErrorCode,
-		StatusCode: err.StatusCode(),
+		StatusCode: err.HTTPResponse.StatusCode,
 	}
 
 	e.lock.RLock()

pkg/handler/unrouted_handler.go

@@ -23,103 +23,31 @@ var (
 	reMimeType       = regexp.MustCompile(`^[a-z]+\/[a-z0-9\-\+\.]+$`)
 )
 
-// HTTPError represents an error with an additional status code attached
-// which may be used when this error is sent in a HTTP response.
-// See the net/http package for standardized status codes.
-type HTTPError interface {
-	error
-	ErrorCode() string
-	StatusCode() int
-	Body() []byte
-}
-
-type httpError struct {
-	errorCode  string
-	message    string
-	statusCode int
-}
-
-func (err httpError) Error() string {
-	return err.errorCode + ": " + err.message
-}
-
-func (err httpError) StatusCode() int {
-	return err.statusCode
-}
-
-func (err httpError) ErrorCode() string {
-	return err.errorCode
-}
-
-func (err httpError) Body() []byte {
-	return []byte(err.Error())
-}
-
-// NewHTTPError adds the given status code to the provided error and returns
-// the new error instance. The status code may be used in corresponding HTTP
-// responses. See the net/http package for standardized status codes.
-func NewHTTPError(errCode string, message string, statusCode int) HTTPError {
-	return httpError{errCode, message, statusCode}
-}
-
 var (
-	ErrUnsupportedVersion               = NewHTTPError("ERR_UNSUPPORTED_VERSION", "missing, invalid or unsupported Tus-Resumable header", http.StatusPreconditionFailed)
+	ErrUnsupportedVersion               = NewError("ERR_UNSUPPORTED_VERSION", "missing, invalid or unsupported Tus-Resumable header", http.StatusPreconditionFailed)
-	ErrMaxSizeExceeded                  = NewHTTPError("ERR_MAX_SIZE_EXCEEDED", "maximum size exceeded", http.StatusRequestEntityTooLarge)
+	ErrMaxSizeExceeded                  = NewError("ERR_MAX_SIZE_EXCEEDED", "maximum size exceeded", http.StatusRequestEntityTooLarge)
-	ErrInvalidContentType               = NewHTTPError("ERR_INVALID_CONTENT_TYPE", "missing or invalid Content-Type header", http.StatusBadRequest)
+	ErrInvalidContentType               = NewError("ERR_INVALID_CONTENT_TYPE", "missing or invalid Content-Type header", http.StatusBadRequest)
-	ErrInvalidUploadLength              = NewHTTPError("ERR_INVALID_UPLOAD_LENGTH", "missing or invalid Upload-Length header", http.StatusBadRequest)
+	ErrInvalidUploadLength              = NewError("ERR_INVALID_UPLOAD_LENGTH", "missing or invalid Upload-Length header", http.StatusBadRequest)
-	ErrInvalidOffset                    = NewHTTPError("ERR_INVALID_OFFSET", "missing or invalid Upload-Offset header", http.StatusBadRequest)
+	ErrInvalidOffset                    = NewError("ERR_INVALID_OFFSET", "missing or invalid Upload-Offset header", http.StatusBadRequest)
-	ErrNotFound                         = NewHTTPError("ERR_UPLOAD_NOT_FOUND", "upload not found", http.StatusNotFound)
+	ErrNotFound                         = NewError("ERR_UPLOAD_NOT_FOUND", "upload not found", http.StatusNotFound)
-	ErrFileLocked                       = NewHTTPError("ERR_UPLOAD_LOCKED", "file currently locked", http.StatusLocked)
+	ErrFileLocked                       = NewError("ERR_UPLOAD_LOCKED", "file currently locked", http.StatusLocked)
-	ErrMismatchOffset                   = NewHTTPError("ERR_MISMATCHED_OFFSET", "mismatched offset", http.StatusConflict)
+	ErrMismatchOffset                   = NewError("ERR_MISMATCHED_OFFSET", "mismatched offset", http.StatusConflict)
-	ErrSizeExceeded                     = NewHTTPError("ERR_UPLOAD_SIZE_EXCEEDED", "upload's size exceeded", http.StatusRequestEntityTooLarge)
+	ErrSizeExceeded                     = NewError("ERR_UPLOAD_SIZE_EXCEEDED", "upload's size exceeded", http.StatusRequestEntityTooLarge)
-	ErrNotImplemented                   = NewHTTPError("ERR_NOT_IMPLEMENTED", "feature not implemented", http.StatusNotImplemented)
+	ErrNotImplemented                   = NewError("ERR_NOT_IMPLEMENTED", "feature not implemented", http.StatusNotImplemented)
-	ErrUploadNotFinished                = NewHTTPError("ERR_UPLOAD_NOT_FINISHED", "one of the partial uploads is not finished", http.StatusBadRequest)
+	ErrUploadNotFinished                = NewError("ERR_UPLOAD_NOT_FINISHED", "one of the partial uploads is not finished", http.StatusBadRequest)
-	ErrInvalidConcat                    = NewHTTPError("ERR_INVALID_CONCAT", "invalid Upload-Concat header", http.StatusBadRequest)
+	ErrInvalidConcat                    = NewError("ERR_INVALID_CONCAT", "invalid Upload-Concat header", http.StatusBadRequest)
-	ErrModifyFinal                      = NewHTTPError("ERR_MODIFY_FINAL", "modifying a final upload is not allowed", http.StatusForbidden)
+	ErrModifyFinal                      = NewError("ERR_MODIFY_FINAL", "modifying a final upload is not allowed", http.StatusForbidden)
-	ErrUploadLengthAndUploadDeferLength = NewHTTPError("ERR_AMBIGUOUS_UPLOAD_LENGTH", "provided both Upload-Length and Upload-Defer-Length", http.StatusBadRequest)
+	ErrUploadLengthAndUploadDeferLength = NewError("ERR_AMBIGUOUS_UPLOAD_LENGTH", "provided both Upload-Length and Upload-Defer-Length", http.StatusBadRequest)
-	ErrInvalidUploadDeferLength         = NewHTTPError("ERR_INVALID_UPLOAD_LENGTH_DEFER", "invalid Upload-Defer-Length header", http.StatusBadRequest)
+	ErrInvalidUploadDeferLength         = NewError("ERR_INVALID_UPLOAD_LENGTH_DEFER", "invalid Upload-Defer-Length header", http.StatusBadRequest)
-	ErrUploadStoppedByServer            = NewHTTPError("ERR_UPLOAD_STOPPED", "upload has been stopped by server", http.StatusBadRequest)
+	ErrUploadStoppedByServer            = NewError("ERR_UPLOAD_STOPPED", "upload has been stopped by server", http.StatusBadRequest)
+	ErrUploadRejectedByServer           = NewError("ERR_UPLOAD_REJECTED", "upload creation has been rejected by server", http.StatusBadRequest)
 
 	// TODO: These two responses are 500 for backwards compatability. We should discuss
 	// whether it is better to more them to 4XX status codes.
-	ErrReadTimeout     = NewHTTPError("ERR_READ_TIMEOUT", "timeout while reading request body", http.StatusInternalServerError)
+	ErrReadTimeout     = NewError("ERR_READ_TIMEOUT", "timeout while reading request body", http.StatusInternalServerError)
-	ErrConnectionReset = NewHTTPError("ERR_CONNECTION_RESET", "TCP connection reset by peer", http.StatusInternalServerError)
+	ErrConnectionReset = NewError("ERR_CONNECTION_RESET", "TCP connection reset by peer", http.StatusInternalServerError)
 )
 
-// HTTPRequest contains basic details of an incoming HTTP request.
-type HTTPRequest struct {
-	// Method is the HTTP method, e.g. POST or PATCH
-	Method string
-	// URI is the full HTTP request URI, e.g. /files/fooo
-	URI string
-	// RemoteAddr contains the network address that sent the request
-	RemoteAddr string
-	// Header contains all HTTP headers as present in the HTTP request.
-	Header http.Header
-}
-
-// HookEvent represents an event from tusd which can be handled by the application.
-type HookEvent struct {
-	// Upload contains information about the upload that caused this hook
-	// to be fired.
-	Upload FileInfo
-	// HTTPRequest contains details about the HTTP request that reached
-	// tusd.
-	HTTPRequest HTTPRequest
-}
-
-func newHookEvent(info FileInfo, r *http.Request) HookEvent {
-	return HookEvent{
-		Upload: info,
-		HTTPRequest: HTTPRequest{
-			Method:     r.Method,
-			URI:        r.RequestURI,
-			RemoteAddr: r.RemoteAddr,
-			Header:     r.Header,
-		},
-	}
-}
-
 // UnroutedHandler exposes methods to handle requests as part of the tus protocol,
 // such as PostFile, HeadFile, PatchFile and DelFile. In addition the GetFile method
 // is provided which is, however, not part of the specification.
@@ -266,7 +194,9 @@ func (handler *UnroutedHandler) Middleware(h http.Handler) http.Handler {
 			// will be ignored or interpreted as a rejection.
 			// For example, the Presto engine, which is used in older versions of
 			// Opera, Opera Mobile and Opera Mini, handles CORS this way.
-			handler.sendResp(w, r, http.StatusOK)
+			handler.sendResp(w, r, HTTPResponse{
+				StatusCode: http.StatusOK,
+			})
 			return
 		}
 
@@ -353,11 +283,18 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 		PartialUploads: partialUploadIDs,
 	}
 
+	resp := HTTPResponse{
+		StatusCode: http.StatusCreated,
+		Headers:    HTTPHeaders{},
+	}
+
 	if handler.config.PreUploadCreateCallback != nil {
-		if err := handler.config.PreUploadCreateCallback(newHookEvent(info, r)); err != nil {
+		resp2, err := handler.config.PreUploadCreateCallback(newHookEvent(info, r))
+		if err != nil {
 			handler.sendError(w, r, err)
 			return
 		}
+		resp = resp.MergeWith(resp2)
 	}
 
 	upload, err := handler.composer.Core.NewUpload(ctx, info)
@@ -377,7 +314,7 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 	// Add the Location header directly after creating the new resource to even
 	// include it in cases of failure when an error is returned
 	url := handler.absFileURL(r, id)
-	w.Header().Set("Location", url)
+	resp.Headers["Location"] = url
 
 	handler.Metrics.incUploadsCreated()
 	handler.log("UploadCreated", "id", id, "size", i64toa(size), "url", url)
@@ -410,7 +347,8 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 			defer lock.Unlock()
 		}
 
-		if err := handler.writeChunk(ctx, upload, info, w, r); err != nil {
+		resp, err = handler.writeChunk(ctx, upload, info, resp, r)
+		if err != nil {
 			handler.sendError(w, r, err)
 			return
 		}
@@ -418,13 +356,14 @@ func (handler *UnroutedHandler) PostFile(w http.ResponseWriter, r *http.Request)
 		// Directly finish the upload if the upload is empty (i.e. has a size of 0).
 		// This statement is in an else-if block to avoid causing duplicate calls
 		// to finishUploadIfComplete if an upload is empty and contains a chunk.
-		if err := handler.finishUploadIfComplete(ctx, upload, info, r); err != nil {
+		resp, err = handler.finishUploadIfComplete(ctx, upload, info, resp, r)
+		if err != nil {
 			handler.sendError(w, r, err)
 			return
 		}
 	}
 
-	handler.sendResp(w, r, http.StatusCreated)
+	handler.sendResp(w, r, resp)
 }
 
 // HeadFile returns the length and offset for the HEAD request
@@ -459,9 +398,14 @@ func (handler *UnroutedHandler) HeadFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
+	resp := HTTPResponse{
+		StatusCode: http.StatusOK,
+		Headers:    make(HTTPHeaders),
+	}
+
 	// Add Upload-Concat header if possible
 	if info.IsPartial {
-		w.Header().Set("Upload-Concat", "partial")
+		resp.Headers["Upload-Concat"] = "partial"
 	}
 
 	if info.IsFinal {
@@ -472,23 +416,23 @@ func (handler *UnroutedHandler) HeadFile(w http.ResponseWriter, r *http.Request)
 		// Remove trailing space
 		v = v[:len(v)-1]
 
-		w.Header().Set("Upload-Concat", v)
+		resp.Headers["Upload-Concat"] = v
 	}
 
 	if len(info.MetaData) != 0 {
-		w.Header().Set("Upload-Metadata", SerializeMetadataHeader(info.MetaData))
+		resp.Headers["Upload-Metadata"] = SerializeMetadataHeader(info.MetaData)
 	}
 
 	if info.SizeIsDeferred {
-		w.Header().Set("Upload-Defer-Length", UploadLengthDeferred)
+		resp.Headers["Upload-Defer-Length"] = UploadLengthDeferred
 	} else {
-		w.Header().Set("Upload-Length", strconv.FormatInt(info.Size, 10))
+		resp.Headers["Upload-Length"] = strconv.FormatInt(info.Size, 10)
-		w.Header().Set("Content-Length", strconv.FormatInt(info.Size, 10))
+		resp.Headers["Content-Length"] = strconv.FormatInt(info.Size, 10)
 	}
 
-	w.Header().Set("Cache-Control", "no-store")
+	resp.Headers["Cache-Control"] = "no-store"
-	w.Header().Set("Upload-Offset", strconv.FormatInt(info.Offset, 10))
+	resp.Headers["Upload-Offset"] = strconv.FormatInt(info.Offset, 10)
-	handler.sendResp(w, r, http.StatusOK)
+	handler.sendResp(w, r, resp)
 }
 
 // PatchFile adds a chunk to an upload. This operation is only allowed
@@ -548,10 +492,15 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 		return
 	}
 
+	resp := HTTPResponse{
+		StatusCode: http.StatusNoContent,
+		Headers:    make(HTTPHeaders, 1), // Initialize map, so writeChunk can set the Upload-Offset header.
+	}
+
 	// Do not proxy the call to the data store if the upload is already completed
 	if !info.SizeIsDeferred && info.Offset == info.Size {
-		w.Header().Set("Upload-Offset", strconv.FormatInt(offset, 10))
+		resp.Headers["Upload-Offset"] = strconv.FormatInt(offset, 10)
-		handler.sendResp(w, r, http.StatusNoContent)
+		handler.sendResp(w, r, resp)
 		return
 	}
 
@@ -580,18 +529,19 @@ func (handler *UnroutedHandler) PatchFile(w http.ResponseWriter, r *http.Request
 		info.SizeIsDeferred = false
 	}
 
-	if err := handler.writeChunk(ctx, upload, info, w, r); err != nil {
+	resp, err = handler.writeChunk(ctx, upload, info, resp, r)
+	if err != nil {
 		handler.sendError(w, r, err)
 		return
 	}
 
-	handler.sendResp(w, r, http.StatusNoContent)
+	handler.sendResp(w, r, resp)
 }
 
 // writeChunk reads the body from the requests r and appends it to the upload
 // with the corresponding id. Afterwards, it will set the necessary response
 // headers but will not send the response.
-func (handler *UnroutedHandler) writeChunk(ctx context.Context, upload Upload, info FileInfo, w http.ResponseWriter, r *http.Request) error {
+func (handler *UnroutedHandler) writeChunk(ctx context.Context, upload Upload, info FileInfo, resp HTTPResponse, r *http.Request) (HTTPResponse, error) {
 	// Get Content-Length if possible
 	length := r.ContentLength
 	offset := info.Offset
@@ -599,7 +549,7 @@ func (handler *UnroutedHandler) writeChunk(ctx context.Context, upload Upload, i
 
 	// Test if this upload fits into the file's size
 	if !info.SizeIsDeferred && offset+length > info.Size {
-		return ErrSizeExceeded
+		return resp, ErrSizeExceeded
 	}
 
 	maxSize := info.Size - offset
@@ -679,27 +629,27 @@ func (handler *UnroutedHandler) writeChunk(ctx context.Context, upload Upload, i
 	handler.log("ChunkWriteComplete", "id", id, "bytesWritten", i64toa(bytesWritten))
 
 	if err != nil {
-		return err
+		return resp, err
 	}
 
 	// Send new offset to client
 	newOffset := offset + bytesWritten
-	w.Header().Set("Upload-Offset", strconv.FormatInt(newOffset, 10))
+	resp.Headers["Upload-Offset"] = strconv.FormatInt(newOffset, 10)
 	handler.Metrics.incBytesReceived(uint64(bytesWritten))
 	info.Offset = newOffset
 
-	return handler.finishUploadIfComplete(ctx, upload, info, r)
+	return handler.finishUploadIfComplete(ctx, upload, info, resp, r)
 }
 
 // finishUploadIfComplete checks whether an upload is completed (i.e. upload offset
 // matches upload size) and if so, it will call the data store's FinishUpload
 // function and send the necessary message on the CompleteUpload channel.
-func (handler *UnroutedHandler) finishUploadIfComplete(ctx context.Context, upload Upload, info FileInfo, r *http.Request) error {
+func (handler *UnroutedHandler) finishUploadIfComplete(ctx context.Context, upload Upload, info FileInfo, resp HTTPResponse, r *http.Request) (HTTPResponse, error) {
 	// If the upload is completed, ...
 	if !info.SizeIsDeferred && info.Offset == info.Size {
 		// ... allow custom mechanism to finish and cleanup the upload
 		if err := upload.FinishUpload(ctx); err != nil {
-			return err
+			return resp, err
 		}
 
 		// ... send the info out to the channel
@@ -710,13 +660,15 @@ func (handler *UnroutedHandler) finishUploadIfComplete(ctx context.Context, uplo
 		handler.Metrics.incUploadsFinished()
 
 		if handler.config.PreFinishResponseCallback != nil {
-			if err := handler.config.PreFinishResponseCallback(newHookEvent(info, r)); err != nil {
+			resp2, err := handler.config.PreFinishResponseCallback(newHookEvent(info, r))
-				return err
+			if err != nil {
+				return resp, err
 			}
+			resp = resp.MergeWith(resp2)
 		}
 	}
 
-	return nil
+	return resp, nil
 }
 
 // GetFile handles requests to download a file using a GET request. This is not
@@ -752,16 +704,21 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	// Set headers before sending responses
-	w.Header().Set("Content-Length", strconv.FormatInt(info.Offset, 10))
-
 	contentType, contentDisposition := filterContentType(info)
-	w.Header().Set("Content-Type", contentType)
+	resp := HTTPResponse{
-	w.Header().Set("Content-Disposition", contentDisposition)
+		StatusCode: http.StatusOK,
+		Headers: HTTPHeaders{
+			"Content-Length":      strconv.FormatInt(info.Offset, 10),
+			"Content-Type":        contentType,
+			"Content-Disposition": contentDisposition,
+		},
+		Body: "", // Body is intentionally left empty, and we copy it manually in later.
+	}
 
 	// If no data has been uploaded yet, respond with an empty "204 No Content" status.
 	if info.Offset == 0 {
-		handler.sendResp(w, r, http.StatusNoContent)
+		resp.StatusCode = http.StatusNoContent
+		handler.sendResp(w, r, resp)
 		return
 	}
 
@@ -771,7 +728,7 @@ func (handler *UnroutedHandler) GetFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	handler.sendResp(w, r, http.StatusOK)
+	handler.sendResp(w, r, resp)
 	io.Copy(w, src)
 
 	// Try to close the reader if the io.Closer interface is implemented
@@ -888,7 +845,9 @@ func (handler *UnroutedHandler) DelFile(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	handler.sendResp(w, r, http.StatusNoContent)
+	handler.sendResp(w, r, HTTPResponse{
+		StatusCode: http.StatusNoContent,
+	})
 }
 
 // terminateUpload passes a given upload to the DataStore's Terminater,
@@ -950,33 +909,27 @@ func (handler *UnroutedHandler) sendError(w http.ResponseWriter, r *http.Request
 	//	err = nil
 	//}
 
-	statusErr, ok := err.(HTTPError)
+	detailedErr, ok := err.(Error)
 	if !ok {
 		handler.log("InternalServerError", "message", err.Error(), "method", r.Method, "path", r.URL.Path, "requestId", getRequestId(r))
-		statusErr = NewHTTPError("ERR_INTERNAL_SERVER_ERROR", err.Error(), http.StatusInternalServerError)
+		detailedErr = NewError("ERR_INTERNAL_SERVER_ERROR", err.Error(), http.StatusInternalServerError)
 	}
 
-	reason := append(statusErr.Body(), '\n')
+	// If we are sending the response for a HEAD request, ensure that we are not including
+	// any response body.
 	if r.Method == "HEAD" {
-		reason = nil
+		detailedErr.HTTPResponse.Body = ""
 	}
 
-	// TODO: Allow JSON response
+	handler.sendResp(w, r, detailedErr.HTTPResponse)
-	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	handler.Metrics.incErrorsTotal(detailedErr)
-	w.Header().Set("Content-Length", strconv.Itoa(len(reason)))
-	w.WriteHeader(statusErr.StatusCode())
-	w.Write(reason)
-
-	handler.log("ResponseOutgoing", "status", strconv.Itoa(statusErr.StatusCode()), "method", r.Method, "path", r.URL.Path, "error", statusErr.ErrorCode(), "requestId", getRequestId(r))
-
-	handler.Metrics.incErrorsTotal(statusErr)
 }
 
 // sendResp writes the header to w with the specified status code.
-func (handler *UnroutedHandler) sendResp(w http.ResponseWriter, r *http.Request, status int) {
+func (handler *UnroutedHandler) sendResp(w http.ResponseWriter, r *http.Request, resp HTTPResponse) {
-	w.WriteHeader(status)
+	resp.writeTo(w)
 
-	handler.log("ResponseOutgoing", "status", strconv.Itoa(status), "method", r.Method, "path", r.URL.Path, "requestId", getRequestId(r))
+	handler.log("ResponseOutgoing", "status", strconv.Itoa(resp.StatusCode), "method", r.Method, "path", r.URL.Path, "requestId", getRequestId(r), "body", resp.Body)
 }
 
 // Make an absolute URLs to the given upload id. If the base path is absolute

pkg/proto/v1/hook.pb.go

@@ -1,475 +0,0 @@
-// Code generated by protoc-gen-go. DO NOT EDIT.
-// source: v1/hook.proto
-
-package v1
-
-import (
-	context "context"
-	fmt "fmt"
-	proto "github.com/golang/protobuf/proto"
-	any "github.com/golang/protobuf/ptypes/any"
-	grpc "google.golang.org/grpc"
-	codes "google.golang.org/grpc/codes"
-	status "google.golang.org/grpc/status"
-	math "math"
-)
-
-// Reference imports to suppress errors if they are not otherwise used.
-var _ = proto.Marshal
-var _ = fmt.Errorf
-var _ = math.Inf
-
-// This is a compile-time assertion to ensure that this generated file
-// is compatible with the proto package it is being compiled against.
-// A compilation error at this line likely means your copy of the
-// proto package needs to be updated.
-const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
-
-// Uploaded data
-type Upload struct {
-	// Unique integer identifier of the uploaded file
-	Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
-	// Total file size in bytes specified in the NewUpload call
-	Size int64 `protobuf:"varint,2,opt,name=Size,proto3" json:"Size,omitempty"`
-	// Indicates whether the total file size is deferred until later
-	SizeIsDeferred bool `protobuf:"varint,3,opt,name=SizeIsDeferred,proto3" json:"SizeIsDeferred,omitempty"`
-	// Offset in bytes (zero-based)
-	Offset   int64             `protobuf:"varint,4,opt,name=Offset,proto3" json:"Offset,omitempty"`
-	MetaData map[string]string `protobuf:"bytes,5,rep,name=metaData,proto3" json:"metaData,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
-	// Indicates that this is a partial upload which will later be used to form
-	// a final upload by concatenation. Partial uploads should not be processed
-	// when they are finished since they are only incomplete chunks of files.
-	IsPartial bool `protobuf:"varint,6,opt,name=isPartial,proto3" json:"isPartial,omitempty"`
-	// Indicates that this is a final upload
-	IsFinal bool `protobuf:"varint,7,opt,name=isFinal,proto3" json:"isFinal,omitempty"`
-	// If the upload is a final one (see IsFinal) this will be a non-empty
-	// ordered slice containing the ids of the uploads of which the final upload
-	// will consist after concatenation.
-	PartialUploads []string `protobuf:"bytes,8,rep,name=partialUploads,proto3" json:"partialUploads,omitempty"`
-	// Storage contains information about where the data storage saves the upload,
-	// for example a file path. The available values vary depending on what data
-	// store is used. This map may also be nil.
-	Storage              map[string]string `protobuf:"bytes,9,rep,name=storage,proto3" json:"storage,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
-	XXX_NoUnkeyedLiteral struct{}          `json:"-"`
-	XXX_unrecognized     []byte            `json:"-"`
-	XXX_sizecache        int32             `json:"-"`
-}
-
-func (m *Upload) Reset()         { *m = Upload{} }
-func (m *Upload) String() string { return proto.CompactTextString(m) }
-func (*Upload) ProtoMessage()    {}
-func (*Upload) Descriptor() ([]byte, []int) {
-	return fileDescriptor_581082325ef044c1, []int{0}
-}
-
-func (m *Upload) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_Upload.Unmarshal(m, b)
-}
-func (m *Upload) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_Upload.Marshal(b, m, deterministic)
-}
-func (m *Upload) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_Upload.Merge(m, src)
-}
-func (m *Upload) XXX_Size() int {
-	return xxx_messageInfo_Upload.Size(m)
-}
-func (m *Upload) XXX_DiscardUnknown() {
-	xxx_messageInfo_Upload.DiscardUnknown(m)
-}
-
-var xxx_messageInfo_Upload proto.InternalMessageInfo
-
-func (m *Upload) GetId() string {
-	if m != nil {
-		return m.Id
-	}
-	return ""
-}
-
-func (m *Upload) GetSize() int64 {
-	if m != nil {
-		return m.Size
-	}
-	return 0
-}
-
-func (m *Upload) GetSizeIsDeferred() bool {
-	if m != nil {
-		return m.SizeIsDeferred
-	}
-	return false
-}
-
-func (m *Upload) GetOffset() int64 {
-	if m != nil {
-		return m.Offset
-	}
-	return 0
-}
-
-func (m *Upload) GetMetaData() map[string]string {
-	if m != nil {
-		return m.MetaData
-	}
-	return nil
-}
-
-func (m *Upload) GetIsPartial() bool {
-	if m != nil {
-		return m.IsPartial
-	}
-	return false
-}
-
-func (m *Upload) GetIsFinal() bool {
-	if m != nil {
-		return m.IsFinal
-	}
-	return false
-}
-
-func (m *Upload) GetPartialUploads() []string {
-	if m != nil {
-		return m.PartialUploads
-	}
-	return nil
-}
-
-func (m *Upload) GetStorage() map[string]string {
-	if m != nil {
-		return m.Storage
-	}
-	return nil
-}
-
-type HTTPRequest struct {
-	// Method is the HTTP method, e.g. POST or PATCH
-	Method string `protobuf:"bytes,1,opt,name=method,proto3" json:"method,omitempty"`
-	// URI is the full HTTP request URI, e.g. /files/fooo
-	Uri string `protobuf:"bytes,2,opt,name=uri,proto3" json:"uri,omitempty"`
-	// RemoteAddr contains the network address that sent the request
-	RemoteAddr           string   `protobuf:"bytes,3,opt,name=remoteAddr,proto3" json:"remoteAddr,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
-}
-
-func (m *HTTPRequest) Reset()         { *m = HTTPRequest{} }
-func (m *HTTPRequest) String() string { return proto.CompactTextString(m) }
-func (*HTTPRequest) ProtoMessage()    {}
-func (*HTTPRequest) Descriptor() ([]byte, []int) {
-	return fileDescriptor_581082325ef044c1, []int{1}
-}
-
-func (m *HTTPRequest) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_HTTPRequest.Unmarshal(m, b)
-}
-func (m *HTTPRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_HTTPRequest.Marshal(b, m, deterministic)
-}
-func (m *HTTPRequest) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_HTTPRequest.Merge(m, src)
-}
-func (m *HTTPRequest) XXX_Size() int {
-	return xxx_messageInfo_HTTPRequest.Size(m)
-}
-func (m *HTTPRequest) XXX_DiscardUnknown() {
-	xxx_messageInfo_HTTPRequest.DiscardUnknown(m)
-}
-
-var xxx_messageInfo_HTTPRequest proto.InternalMessageInfo
-
-func (m *HTTPRequest) GetMethod() string {
-	if m != nil {
-		return m.Method
-	}
-	return ""
-}
-
-func (m *HTTPRequest) GetUri() string {
-	if m != nil {
-		return m.Uri
-	}
-	return ""
-}
-
-func (m *HTTPRequest) GetRemoteAddr() string {
-	if m != nil {
-		return m.RemoteAddr
-	}
-	return ""
-}
-
-// Hook's data
-type Hook struct {
-	// Upload contains information about the upload that caused this hook
-	// to be fired.
-	Upload *Upload `protobuf:"bytes,1,opt,name=upload,proto3" json:"upload,omitempty"`
-	// HTTPRequest contains details about the HTTP request that reached
-	// tusd.
-	HttpRequest *HTTPRequest `protobuf:"bytes,2,opt,name=httpRequest,proto3" json:"httpRequest,omitempty"`
-	// The hook name
-	Name                 string   `protobuf:"bytes,3,opt,name=name,proto3" json:"name,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
-}
-
-func (m *Hook) Reset()         { *m = Hook{} }
-func (m *Hook) String() string { return proto.CompactTextString(m) }
-func (*Hook) ProtoMessage()    {}
-func (*Hook) Descriptor() ([]byte, []int) {
-	return fileDescriptor_581082325ef044c1, []int{2}
-}
-
-func (m *Hook) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_Hook.Unmarshal(m, b)
-}
-func (m *Hook) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_Hook.Marshal(b, m, deterministic)
-}
-func (m *Hook) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_Hook.Merge(m, src)
-}
-func (m *Hook) XXX_Size() int {
-	return xxx_messageInfo_Hook.Size(m)
-}
-func (m *Hook) XXX_DiscardUnknown() {
-	xxx_messageInfo_Hook.DiscardUnknown(m)
-}
-
-var xxx_messageInfo_Hook proto.InternalMessageInfo
-
-func (m *Hook) GetUpload() *Upload {
-	if m != nil {
-		return m.Upload
-	}
-	return nil
-}
-
-func (m *Hook) GetHttpRequest() *HTTPRequest {
-	if m != nil {
-		return m.HttpRequest
-	}
-	return nil
-}
-
-func (m *Hook) GetName() string {
-	if m != nil {
-		return m.Name
-	}
-	return ""
-}
-
-// Request data to send hook
-type SendRequest struct {
-	// The hook data
-	Hook                 *Hook    `protobuf:"bytes,1,opt,name=hook,proto3" json:"hook,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
-}
-
-func (m *SendRequest) Reset()         { *m = SendRequest{} }
-func (m *SendRequest) String() string { return proto.CompactTextString(m) }
-func (*SendRequest) ProtoMessage()    {}
-func (*SendRequest) Descriptor() ([]byte, []int) {
-	return fileDescriptor_581082325ef044c1, []int{3}
-}
-
-func (m *SendRequest) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_SendRequest.Unmarshal(m, b)
-}
-func (m *SendRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_SendRequest.Marshal(b, m, deterministic)
-}
-func (m *SendRequest) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_SendRequest.Merge(m, src)
-}
-func (m *SendRequest) XXX_Size() int {
-	return xxx_messageInfo_SendRequest.Size(m)
-}
-func (m *SendRequest) XXX_DiscardUnknown() {
-	xxx_messageInfo_SendRequest.DiscardUnknown(m)
-}
-
-var xxx_messageInfo_SendRequest proto.InternalMessageInfo
-
-func (m *SendRequest) GetHook() *Hook {
-	if m != nil {
-		return m.Hook
-	}
-	return nil
-}
-
-// Response that contains data for sended hook
-type SendResponse struct {
-	// The response of the hook.
-	Response             *any.Any `protobuf:"bytes,1,opt,name=response,proto3" json:"response,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
-}
-
-func (m *SendResponse) Reset()         { *m = SendResponse{} }
-func (m *SendResponse) String() string { return proto.CompactTextString(m) }
-func (*SendResponse) ProtoMessage()    {}
-func (*SendResponse) Descriptor() ([]byte, []int) {
-	return fileDescriptor_581082325ef044c1, []int{4}
-}
-
-func (m *SendResponse) XXX_Unmarshal(b []byte) error {
-	return xxx_messageInfo_SendResponse.Unmarshal(m, b)
-}
-func (m *SendResponse) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
-	return xxx_messageInfo_SendResponse.Marshal(b, m, deterministic)
-}
-func (m *SendResponse) XXX_Merge(src proto.Message) {
-	xxx_messageInfo_SendResponse.Merge(m, src)
-}
-func (m *SendResponse) XXX_Size() int {
-	return xxx_messageInfo_SendResponse.Size(m)
-}
-func (m *SendResponse) XXX_DiscardUnknown() {
-	xxx_messageInfo_SendResponse.DiscardUnknown(m)
-}
-
-var xxx_messageInfo_SendResponse proto.InternalMessageInfo
-
-func (m *SendResponse) GetResponse() *any.Any {
-	if m != nil {
-		return m.Response
-	}
-	return nil
-}
-
-func init() {
-	proto.RegisterType((*Upload)(nil), "v1.Upload")
-	proto.RegisterMapType((map[string]string)(nil), "v1.Upload.MetaDataEntry")
-	proto.RegisterMapType((map[string]string)(nil), "v1.Upload.StorageEntry")
-	proto.RegisterType((*HTTPRequest)(nil), "v1.HTTPRequest")
-	proto.RegisterType((*Hook)(nil), "v1.Hook")
-	proto.RegisterType((*SendRequest)(nil), "v1.SendRequest")
-	proto.RegisterType((*SendResponse)(nil), "v1.SendResponse")
-}
-
-func init() {
-	proto.RegisterFile("v1/hook.proto", fileDescriptor_581082325ef044c1)
-}
-
-var fileDescriptor_581082325ef044c1 = []byte{
-	// 477 bytes of a gzipped FileDescriptorProto
-	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x94, 0x52, 0x4d, 0x6f, 0xd3, 0x40,
-	0x10, 0x25, 0xb1, 0xeb, 0xd8, 0xe3, 0xb6, 0x54, 0xab, 0x0a, 0x96, 0xa8, 0x42, 0x96, 0x0f, 0xc8,
-	0x52, 0x25, 0x07, 0x07, 0x0e, 0x28, 0x5c, 0xa8, 0x54, 0x50, 0x39, 0x20, 0xaa, 0x4d, 0x11, 0xe7,
-	0x2d, 0xde, 0x24, 0x56, 0x1c, 0xaf, 0xbb, 0x5e, 0x5b, 0x0a, 0x3f, 0x8a, 0xdf, 0x88, 0xf6, 0xc3,
-	0x8d, 0xe9, 0x8d, 0x93, 0x67, 0xde, 0xbc, 0x79, 0xf3, 0x3c, 0x3b, 0x70, 0xd2, 0x65, 0xb3, 0x0d,
-	0xe7, 0xdb, 0xb4, 0x16, 0x5c, 0x72, 0x34, 0xee, 0xb2, 0xe9, 0xab, 0x35, 0xe7, 0xeb, 0x92, 0xcd,
-	0x34, 0x72, 0xdf, 0xae, 0x66, 0xb4, 0xda, 0x9b, 0x72, 0xfc, 0xc7, 0x01, 0xef, 0x47, 0x5d, 0x72,
-	0x9a, 0xa3, 0x53, 0x18, 0x17, 0x39, 0x1e, 0x45, 0xa3, 0x24, 0x20, 0xe3, 0x22, 0x47, 0x08, 0xdc,
-	0x65, 0xf1, 0x9b, 0xe1, 0x71, 0x34, 0x4a, 0x1c, 0xa2, 0x63, 0xf4, 0x06, 0x4e, 0xd5, 0xf7, 0x6b,
-	0x73, 0xcd, 0x56, 0x4c, 0x08, 0x96, 0x63, 0x27, 0x1a, 0x25, 0x3e, 0x79, 0x82, 0xa2, 0x17, 0xe0,
-	0x7d, 0x5f, 0xad, 0x1a, 0x26, 0xb1, 0xab, 0xbb, 0x6d, 0x86, 0xde, 0x83, 0xbf, 0x63, 0x92, 0x5e,
-	0x53, 0x49, 0xf1, 0x51, 0xe4, 0x24, 0xe1, 0x1c, 0xa7, 0x5d, 0x96, 0x1a, 0x07, 0xe9, 0x37, 0x5b,
-	0xfa, 0x5c, 0x49, 0xb1, 0x27, 0x8f, 0x4c, 0x74, 0x01, 0x41, 0xd1, 0xdc, 0x52, 0x21, 0x0b, 0x5a,
-	0x62, 0x4f, 0x0f, 0x3c, 0x00, 0x08, 0xc3, 0xa4, 0x68, 0xbe, 0x14, 0x15, 0x2d, 0xf1, 0x44, 0xd7,
-	0xfa, 0x54, 0xb9, 0xad, 0x0d, 0xc9, 0x0c, 0x68, 0xb0, 0x1f, 0x39, 0x49, 0x40, 0x9e, 0xa0, 0x28,
-	0x83, 0x49, 0x23, 0xb9, 0xa0, 0x6b, 0x86, 0x03, 0x6d, 0xea, 0xe5, 0xc0, 0xd4, 0xd2, 0x54, 0x8c,
-	0xa7, 0x9e, 0x37, 0xfd, 0x08, 0x27, 0xff, 0xb8, 0x45, 0x67, 0xe0, 0x6c, 0xd9, 0xde, 0xae, 0x4f,
-	0x85, 0xe8, 0x1c, 0x8e, 0x3a, 0x5a, 0xb6, 0x66, 0x81, 0x01, 0x31, 0xc9, 0x62, 0xfc, 0x61, 0x34,
-	0x5d, 0xc0, 0xf1, 0x50, 0xf5, 0x7f, 0x7a, 0xe3, 0x9f, 0x10, 0xde, 0xdc, 0xdd, 0xdd, 0x12, 0xf6,
-	0xd0, 0xb2, 0x46, 0xaa, 0x45, 0xef, 0x98, 0xdc, 0xf0, 0xfe, 0xe1, 0x6c, 0xa6, 0x24, 0x5b, 0x51,
-	0xd8, 0x76, 0x15, 0xa2, 0xd7, 0x00, 0x82, 0xed, 0xb8, 0x64, 0x57, 0x79, 0x2e, 0xf4, 0xb3, 0x05,
-	0x64, 0x80, 0xc4, 0x0f, 0xe0, 0xde, 0x70, 0xbe, 0x45, 0x31, 0x78, 0xad, 0xfe, 0x73, 0xad, 0x18,
-	0xce, 0xe1, 0xb0, 0x0b, 0x62, 0x2b, 0x28, 0x83, 0x70, 0x23, 0x65, 0x6d, 0x4d, 0xe8, 0x29, 0xe1,
-	0xfc, 0xb9, 0x22, 0x0e, 0xbc, 0x91, 0x21, 0x47, 0x5d, 0x53, 0x45, 0x77, 0xcc, 0x0e, 0xd6, 0x71,
-	0x7c, 0x09, 0xe1, 0x92, 0x55, 0x79, 0x4f, 0xb9, 0x00, 0x57, 0x1d, 0xae, 0x9d, 0xeb, 0x6b, 0x39,
-	0xce, 0xb7, 0x44, 0xa3, 0xf1, 0x27, 0x38, 0x36, 0xe4, 0xa6, 0xe6, 0x55, 0xc3, 0xd0, 0x5b, 0xf0,
-	0x85, 0x8d, 0x6d, 0xc7, 0x79, 0x6a, 0xee, 0x3c, 0xed, 0xef, 0x3c, 0xbd, 0xaa, 0xf6, 0xe4, 0x91,
-	0x35, 0x5f, 0x40, 0xa8, 0xf4, 0x96, 0x4c, 0x74, 0xc5, 0x2f, 0x86, 0x2e, 0xc1, 0x55, 0x82, 0x48,
-	0xfb, 0x1e, 0xf8, 0x98, 0x9e, 0x1d, 0x00, 0xd3, 0x19, 0x3f, 0xbb, 0xf7, 0xb4, 0xe6, 0xbb, 0xbf,
-	0x01, 0x00, 0x00, 0xff, 0xff, 0x8f, 0xd4, 0x14, 0x0d, 0x5e, 0x03, 0x00, 0x00,
-}
-
-// Reference imports to suppress errors if they are not otherwise used.
-var _ context.Context
-var _ grpc.ClientConnInterface
-
-// This is a compile-time assertion to ensure that this generated file
-// is compatible with the grpc package it is being compiled against.
-const _ = grpc.SupportPackageIsVersion6
-
-// HookServiceClient is the client API for HookService service.
-//
-// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
-type HookServiceClient interface {
-	// Sends a hook
-	Send(ctx context.Context, in *SendRequest, opts ...grpc.CallOption) (*SendResponse, error)
-}
-
-type hookServiceClient struct {
-	cc grpc.ClientConnInterface
-}
-
-func NewHookServiceClient(cc grpc.ClientConnInterface) HookServiceClient {
-	return &hookServiceClient{cc}
-}
-
-func (c *hookServiceClient) Send(ctx context.Context, in *SendRequest, opts ...grpc.CallOption) (*SendResponse, error) {
-	out := new(SendResponse)
-	err := c.cc.Invoke(ctx, "/v1.HookService/Send", in, out, opts...)
-	if err != nil {
-		return nil, err
-	}
-	return out, nil
-}
-
-// HookServiceServer is the server API for HookService service.
-type HookServiceServer interface {
-	// Sends a hook
-	Send(context.Context, *SendRequest) (*SendResponse, error)
-}
-
-// UnimplementedHookServiceServer can be embedded to have forward compatible implementations.
-type UnimplementedHookServiceServer struct {
-}
-
-func (*UnimplementedHookServiceServer) Send(ctx context.Context, req *SendRequest) (*SendResponse, error) {
-	return nil, status.Errorf(codes.Unimplemented, "method Send not implemented")
-}
-
-func RegisterHookServiceServer(s *grpc.Server, srv HookServiceServer) {
-	s.RegisterService(&_HookService_serviceDesc, srv)
-}
-
-func _HookService_Send_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
-	in := new(SendRequest)
-	if err := dec(in); err != nil {
-		return nil, err
-	}
-	if interceptor == nil {
-		return srv.(HookServiceServer).Send(ctx, in)
-	}
-	info := &grpc.UnaryServerInfo{
-		Server:     srv,
-		FullMethod: "/v1.HookService/Send",
-	}
-	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
-		return srv.(HookServiceServer).Send(ctx, req.(*SendRequest))
-	}
-	return interceptor(ctx, in, info, handler)
-}
-
-var _HookService_serviceDesc = grpc.ServiceDesc{
-	ServiceName: "v1.HookService",
-	HandlerType: (*HookServiceServer)(nil),
-	Methods: []grpc.MethodDesc{
-		{
-			MethodName: "Send",
-			Handler:    _HookService_Send_Handler,
-		},
-	},
-	Streams:  []grpc.StreamDesc{},
-	Metadata: "v1/hook.proto",
-}

pkg/proto/v2/hook.pb.go

@@ -0,0 +1,555 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: v2/hook.proto
+
+package v2
+
+import (
+	context "context"
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	grpc "google.golang.org/grpc"
+	codes "google.golang.org/grpc/codes"
+	status "google.golang.org/grpc/status"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+// Hook's data
+type HookRequest struct {
+	Type                 string   `protobuf:"bytes,1,opt,name=type,proto3" json:"type,omitempty"`
+	Event                *Event   `protobuf:"bytes,2,opt,name=event,proto3" json:"event,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *HookRequest) Reset()         { *m = HookRequest{} }
+func (m *HookRequest) String() string { return proto.CompactTextString(m) }
+func (*HookRequest) ProtoMessage()    {}
+func (*HookRequest) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{0}
+}
+
+func (m *HookRequest) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_HookRequest.Unmarshal(m, b)
+}
+func (m *HookRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_HookRequest.Marshal(b, m, deterministic)
+}
+func (m *HookRequest) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_HookRequest.Merge(m, src)
+}
+func (m *HookRequest) XXX_Size() int {
+	return xxx_messageInfo_HookRequest.Size(m)
+}
+func (m *HookRequest) XXX_DiscardUnknown() {
+	xxx_messageInfo_HookRequest.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_HookRequest proto.InternalMessageInfo
+
+func (m *HookRequest) GetType() string {
+	if m != nil {
+		return m.Type
+	}
+	return ""
+}
+
+func (m *HookRequest) GetEvent() *Event {
+	if m != nil {
+		return m.Event
+	}
+	return nil
+}
+
+type Event struct {
+	Upload               *FileInfo    `protobuf:"bytes,1,opt,name=upload,proto3" json:"upload,omitempty"`
+	HttpRequest          *HTTPRequest `protobuf:"bytes,2,opt,name=httpRequest,proto3" json:"httpRequest,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}     `json:"-"`
+	XXX_unrecognized     []byte       `json:"-"`
+	XXX_sizecache        int32        `json:"-"`
+}
+
+func (m *Event) Reset()         { *m = Event{} }
+func (m *Event) String() string { return proto.CompactTextString(m) }
+func (*Event) ProtoMessage()    {}
+func (*Event) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{1}
+}
+
+func (m *Event) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_Event.Unmarshal(m, b)
+}
+func (m *Event) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_Event.Marshal(b, m, deterministic)
+}
+func (m *Event) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Event.Merge(m, src)
+}
+func (m *Event) XXX_Size() int {
+	return xxx_messageInfo_Event.Size(m)
+}
+func (m *Event) XXX_DiscardUnknown() {
+	xxx_messageInfo_Event.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Event proto.InternalMessageInfo
+
+func (m *Event) GetUpload() *FileInfo {
+	if m != nil {
+		return m.Upload
+	}
+	return nil
+}
+
+func (m *Event) GetHttpRequest() *HTTPRequest {
+	if m != nil {
+		return m.HttpRequest
+	}
+	return nil
+}
+
+// TODO: Keep consistent naming capitalization
+// Uploaded data
+type FileInfo struct {
+	// Unique integer identifier of the uploaded file
+	Id string `protobuf:"bytes,1,opt,name=id,proto3" json:"id,omitempty"`
+	// Total file size in bytes specified in the NewUpload call
+	Size int64 `protobuf:"varint,2,opt,name=size,proto3" json:"size,omitempty"`
+	// Indicates whether the total file size is deferred until later
+	SizeIsDeferred bool `protobuf:"varint,3,opt,name=sizeIsDeferred,proto3" json:"sizeIsDeferred,omitempty"`
+	// Offset in bytes (zero-based)
+	Offset   int64             `protobuf:"varint,4,opt,name=offset,proto3" json:"offset,omitempty"`
+	MetaData map[string]string `protobuf:"bytes,5,rep,name=metaData,proto3" json:"metaData,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	// Indicates that this is a partial upload which will later be used to form
+	// a final upload by concatenation. Partial uploads should not be processed
+	// when they are finished since they are only incomplete chunks of files.
+	IsPartial bool `protobuf:"varint,6,opt,name=isPartial,proto3" json:"isPartial,omitempty"`
+	// Indicates that this is a final upload
+	IsFinal bool `protobuf:"varint,7,opt,name=isFinal,proto3" json:"isFinal,omitempty"`
+	// If the upload is a final one (see IsFinal) this will be a non-empty
+	// ordered slice containing the ids of the uploads of which the final upload
+	// will consist after concatenation.
+	PartialUploads []string `protobuf:"bytes,8,rep,name=partialUploads,proto3" json:"partialUploads,omitempty"`
+	// Storage contains information about where the data storage saves the upload,
+	// for example a file path. The available values vary depending on what data
+	// store is used. This map may also be nil.
+	Storage              map[string]string `protobuf:"bytes,9,rep,name=storage,proto3" json:"storage,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	XXX_NoUnkeyedLiteral struct{}          `json:"-"`
+	XXX_unrecognized     []byte            `json:"-"`
+	XXX_sizecache        int32             `json:"-"`
+}
+
+func (m *FileInfo) Reset()         { *m = FileInfo{} }
+func (m *FileInfo) String() string { return proto.CompactTextString(m) }
+func (*FileInfo) ProtoMessage()    {}
+func (*FileInfo) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{2}
+}
+
+func (m *FileInfo) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_FileInfo.Unmarshal(m, b)
+}
+func (m *FileInfo) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_FileInfo.Marshal(b, m, deterministic)
+}
+func (m *FileInfo) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_FileInfo.Merge(m, src)
+}
+func (m *FileInfo) XXX_Size() int {
+	return xxx_messageInfo_FileInfo.Size(m)
+}
+func (m *FileInfo) XXX_DiscardUnknown() {
+	xxx_messageInfo_FileInfo.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_FileInfo proto.InternalMessageInfo
+
+func (m *FileInfo) GetId() string {
+	if m != nil {
+		return m.Id
+	}
+	return ""
+}
+
+func (m *FileInfo) GetSize() int64 {
+	if m != nil {
+		return m.Size
+	}
+	return 0
+}
+
+func (m *FileInfo) GetSizeIsDeferred() bool {
+	if m != nil {
+		return m.SizeIsDeferred
+	}
+	return false
+}
+
+func (m *FileInfo) GetOffset() int64 {
+	if m != nil {
+		return m.Offset
+	}
+	return 0
+}
+
+func (m *FileInfo) GetMetaData() map[string]string {
+	if m != nil {
+		return m.MetaData
+	}
+	return nil
+}
+
+func (m *FileInfo) GetIsPartial() bool {
+	if m != nil {
+		return m.IsPartial
+	}
+	return false
+}
+
+func (m *FileInfo) GetIsFinal() bool {
+	if m != nil {
+		return m.IsFinal
+	}
+	return false
+}
+
+func (m *FileInfo) GetPartialUploads() []string {
+	if m != nil {
+		return m.PartialUploads
+	}
+	return nil
+}
+
+func (m *FileInfo) GetStorage() map[string]string {
+	if m != nil {
+		return m.Storage
+	}
+	return nil
+}
+
+type HTTPRequest struct {
+	// Method is the HTTP method, e.g. POST or PATCH
+	Method string `protobuf:"bytes,1,opt,name=method,proto3" json:"method,omitempty"`
+	// URI is the full HTTP request URI, e.g. /files/fooo
+	Uri string `protobuf:"bytes,2,opt,name=uri,proto3" json:"uri,omitempty"`
+	// RemoteAddr contains the network address that sent the request
+	RemoteAddr           string            `protobuf:"bytes,3,opt,name=remoteAddr,proto3" json:"remoteAddr,omitempty"`
+	Header               map[string]string `protobuf:"bytes,4,rep,name=header,proto3" json:"header,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	XXX_NoUnkeyedLiteral struct{}          `json:"-"`
+	XXX_unrecognized     []byte            `json:"-"`
+	XXX_sizecache        int32             `json:"-"`
+}
+
+func (m *HTTPRequest) Reset()         { *m = HTTPRequest{} }
+func (m *HTTPRequest) String() string { return proto.CompactTextString(m) }
+func (*HTTPRequest) ProtoMessage()    {}
+func (*HTTPRequest) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{3}
+}
+
+func (m *HTTPRequest) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_HTTPRequest.Unmarshal(m, b)
+}
+func (m *HTTPRequest) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_HTTPRequest.Marshal(b, m, deterministic)
+}
+func (m *HTTPRequest) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_HTTPRequest.Merge(m, src)
+}
+func (m *HTTPRequest) XXX_Size() int {
+	return xxx_messageInfo_HTTPRequest.Size(m)
+}
+func (m *HTTPRequest) XXX_DiscardUnknown() {
+	xxx_messageInfo_HTTPRequest.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_HTTPRequest proto.InternalMessageInfo
+
+func (m *HTTPRequest) GetMethod() string {
+	if m != nil {
+		return m.Method
+	}
+	return ""
+}
+
+func (m *HTTPRequest) GetUri() string {
+	if m != nil {
+		return m.Uri
+	}
+	return ""
+}
+
+func (m *HTTPRequest) GetRemoteAddr() string {
+	if m != nil {
+		return m.RemoteAddr
+	}
+	return ""
+}
+
+func (m *HTTPRequest) GetHeader() map[string]string {
+	if m != nil {
+		return m.Header
+	}
+	return nil
+}
+
+type HookResponse struct {
+	HttpResponse         *HTTPResponse `protobuf:"bytes,1,opt,name=httpResponse,proto3" json:"httpResponse,omitempty"`
+	RejectUpload         bool          `protobuf:"varint,2,opt,name=rejectUpload,proto3" json:"rejectUpload,omitempty"`
+	StopUpload           bool          `protobuf:"varint,3,opt,name=stopUpload,proto3" json:"stopUpload,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}      `json:"-"`
+	XXX_unrecognized     []byte        `json:"-"`
+	XXX_sizecache        int32         `json:"-"`
+}
+
+func (m *HookResponse) Reset()         { *m = HookResponse{} }
+func (m *HookResponse) String() string { return proto.CompactTextString(m) }
+func (*HookResponse) ProtoMessage()    {}
+func (*HookResponse) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{4}
+}
+
+func (m *HookResponse) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_HookResponse.Unmarshal(m, b)
+}
+func (m *HookResponse) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_HookResponse.Marshal(b, m, deterministic)
+}
+func (m *HookResponse) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_HookResponse.Merge(m, src)
+}
+func (m *HookResponse) XXX_Size() int {
+	return xxx_messageInfo_HookResponse.Size(m)
+}
+func (m *HookResponse) XXX_DiscardUnknown() {
+	xxx_messageInfo_HookResponse.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_HookResponse proto.InternalMessageInfo
+
+func (m *HookResponse) GetHttpResponse() *HTTPResponse {
+	if m != nil {
+		return m.HttpResponse
+	}
+	return nil
+}
+
+func (m *HookResponse) GetRejectUpload() bool {
+	if m != nil {
+		return m.RejectUpload
+	}
+	return false
+}
+
+func (m *HookResponse) GetStopUpload() bool {
+	if m != nil {
+		return m.StopUpload
+	}
+	return false
+}
+
+type HTTPResponse struct {
+	StatusCode           int64             `protobuf:"varint,1,opt,name=statusCode,proto3" json:"statusCode,omitempty"`
+	Headers              map[string]string `protobuf:"bytes,2,rep,name=headers,proto3" json:"headers,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	Body                 string            `protobuf:"bytes,3,opt,name=body,proto3" json:"body,omitempty"`
+	XXX_NoUnkeyedLiteral struct{}          `json:"-"`
+	XXX_unrecognized     []byte            `json:"-"`
+	XXX_sizecache        int32             `json:"-"`
+}
+
+func (m *HTTPResponse) Reset()         { *m = HTTPResponse{} }
+func (m *HTTPResponse) String() string { return proto.CompactTextString(m) }
+func (*HTTPResponse) ProtoMessage()    {}
+func (*HTTPResponse) Descriptor() ([]byte, []int) {
+	return fileDescriptor_938ab51c60d4b622, []int{5}
+}
+
+func (m *HTTPResponse) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_HTTPResponse.Unmarshal(m, b)
+}
+func (m *HTTPResponse) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_HTTPResponse.Marshal(b, m, deterministic)
+}
+func (m *HTTPResponse) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_HTTPResponse.Merge(m, src)
+}
+func (m *HTTPResponse) XXX_Size() int {
+	return xxx_messageInfo_HTTPResponse.Size(m)
+}
+func (m *HTTPResponse) XXX_DiscardUnknown() {
+	xxx_messageInfo_HTTPResponse.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_HTTPResponse proto.InternalMessageInfo
+
+func (m *HTTPResponse) GetStatusCode() int64 {
+	if m != nil {
+		return m.StatusCode
+	}
+	return 0
+}
+
+func (m *HTTPResponse) GetHeaders() map[string]string {
+	if m != nil {
+		return m.Headers
+	}
+	return nil
+}
+
+func (m *HTTPResponse) GetBody() string {
+	if m != nil {
+		return m.Body
+	}
+	return ""
+}
+
+func init() {
+	proto.RegisterType((*HookRequest)(nil), "v2.HookRequest")
+	proto.RegisterType((*Event)(nil), "v2.Event")
+	proto.RegisterType((*FileInfo)(nil), "v2.FileInfo")
+	proto.RegisterMapType((map[string]string)(nil), "v2.FileInfo.MetaDataEntry")
+	proto.RegisterMapType((map[string]string)(nil), "v2.FileInfo.StorageEntry")
+	proto.RegisterType((*HTTPRequest)(nil), "v2.HTTPRequest")
+	proto.RegisterMapType((map[string]string)(nil), "v2.HTTPRequest.HeaderEntry")
+	proto.RegisterType((*HookResponse)(nil), "v2.HookResponse")
+	proto.RegisterType((*HTTPResponse)(nil), "v2.HTTPResponse")
+	proto.RegisterMapType((map[string]string)(nil), "v2.HTTPResponse.HeadersEntry")
+}
+
+func init() {
+	proto.RegisterFile("v2/hook.proto", fileDescriptor_938ab51c60d4b622)
+}
+
+var fileDescriptor_938ab51c60d4b622 = []byte{
+	// 578 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x94, 0x54, 0xdb, 0x6e, 0xd3, 0x40,
+	0x10, 0xc5, 0x71, 0x73, 0xf1, 0x38, 0x2d, 0xd5, 0x0a, 0xa1, 0x25, 0xdc, 0x22, 0x0b, 0xa1, 0x3c,
+	0x05, 0xd5, 0x45, 0x5c, 0xca, 0x0b, 0x97, 0xb6, 0x4a, 0x1f, 0x90, 0xaa, 0xa5, 0xbc, 0xb3, 0xc5,
+	0x13, 0x62, 0xe2, 0x7a, 0xcd, 0xee, 0xc6, 0x52, 0xf8, 0x02, 0x3e, 0x08, 0x89, 0x4f, 0xe0, 0xb7,
+	0xd0, 0x5e, 0x42, 0x9c, 0xbc, 0xe5, 0xc9, 0x3b, 0x67, 0xce, 0xcc, 0x9e, 0x3d, 0x3b, 0x5e, 0xd8,
+	0xaf, 0xd3, 0x67, 0x33, 0x21, 0xe6, 0xe3, 0x4a, 0x0a, 0x2d, 0x48, 0xab, 0x4e, 0x93, 0xf7, 0x10,
+	0x4f, 0x84, 0x98, 0x33, 0xfc, 0xb1, 0x40, 0xa5, 0x09, 0x81, 0x3d, 0xbd, 0xac, 0x90, 0x06, 0xc3,
+	0x60, 0x14, 0x31, 0xbb, 0x26, 0x8f, 0xa1, 0x8d, 0x35, 0x96, 0x9a, 0xb6, 0x86, 0xc1, 0x28, 0x4e,
+	0xa3, 0x71, 0x9d, 0x8e, 0xcf, 0x0c, 0xc0, 0x1c, 0x9e, 0x7c, 0x81, 0xb6, 0x8d, 0xc9, 0x13, 0xe8,
+	0x2c, 0xaa, 0x42, 0xf0, 0xcc, 0xd6, 0xc7, 0x69, 0xdf, 0x50, 0xcf, 0xf3, 0x02, 0x2f, 0xca, 0xa9,
+	0x60, 0x3e, 0x47, 0x8e, 0x20, 0x9e, 0x69, 0x5d, 0xf9, 0x2d, 0x7d, 0xd7, 0xdb, 0x86, 0x3a, 0xb9,
+	0xba, 0xba, 0xf4, 0x30, 0x6b, 0x72, 0x92, 0xdf, 0x21, 0xf4, 0x56, 0x7d, 0xc8, 0x01, 0xb4, 0xf2,
+	0xcc, 0x2b, 0x6c, 0xe5, 0x99, 0xd1, 0xac, 0xf2, 0x9f, 0x68, 0x1b, 0x85, 0xcc, 0xae, 0xc9, 0x53,
+	0x38, 0x30, 0xdf, 0x0b, 0x75, 0x8a, 0x53, 0x94, 0x12, 0x33, 0x1a, 0x0e, 0x83, 0x51, 0x8f, 0x6d,
+	0xa1, 0xe4, 0x2e, 0x74, 0xc4, 0x74, 0xaa, 0x50, 0xd3, 0x3d, 0x5b, 0xed, 0x23, 0xf2, 0x02, 0x7a,
+	0x37, 0xa8, 0xf9, 0x29, 0xd7, 0x9c, 0xb6, 0x87, 0xe1, 0x28, 0x4e, 0x07, 0xcd, 0xb3, 0x8c, 0x3f,
+	0xfa, 0xe4, 0x59, 0xa9, 0xe5, 0x92, 0xfd, 0xe7, 0x92, 0x07, 0x10, 0xe5, 0xea, 0x92, 0x4b, 0x9d,
+	0xf3, 0x82, 0x76, 0xec, 0x96, 0x6b, 0x80, 0x50, 0xe8, 0xe6, 0xea, 0x3c, 0x2f, 0x79, 0x41, 0xbb,
+	0x36, 0xb7, 0x0a, 0x8d, 0xde, 0xca, 0x91, 0x3e, 0x5b, 0x93, 0x14, 0xed, 0x0d, 0xc3, 0x51, 0xc4,
+	0xb6, 0x50, 0x72, 0x0c, 0x5d, 0xa5, 0x85, 0xe4, 0xdf, 0x90, 0x46, 0x56, 0xd6, 0xbd, 0x0d, 0x59,
+	0x9f, 0x5c, 0xce, 0xa9, 0x5a, 0x31, 0x07, 0x6f, 0x60, 0x7f, 0x43, 0x2f, 0x39, 0x84, 0x70, 0x8e,
+	0x4b, 0x6f, 0xa1, 0x59, 0x92, 0x3b, 0xd0, 0xae, 0x79, 0xb1, 0x70, 0x26, 0x46, 0xcc, 0x05, 0x27,
+	0xad, 0x57, 0xc1, 0xe0, 0x04, 0xfa, 0xcd, 0xae, 0xbb, 0xd4, 0x26, 0x7f, 0x03, 0x88, 0x1b, 0x77,
+	0x6a, 0xdc, 0xbe, 0x41, 0x3d, 0x13, 0xab, 0xdb, 0xf3, 0x91, 0xe9, 0xb9, 0x90, 0xb9, 0xaf, 0x37,
+	0x4b, 0xf2, 0x08, 0x40, 0xe2, 0x8d, 0xd0, 0xf8, 0x2e, 0xcb, 0xa4, 0xbd, 0xbb, 0x88, 0x35, 0x10,
+	0x72, 0x0c, 0x9d, 0x19, 0xf2, 0x0c, 0x25, 0xdd, 0xb3, 0x36, 0xdc, 0xdf, 0x1a, 0x9f, 0xf1, 0xc4,
+	0x66, 0x9d, 0x11, 0x9e, 0x3a, 0x78, 0x0d, 0x71, 0x03, 0xde, 0xe9, 0x24, 0xbf, 0x02, 0xe8, 0xbb,
+	0xff, 0x44, 0x55, 0xa2, 0x54, 0x48, 0x9e, 0x43, 0xdf, 0x0d, 0xa8, 0x8b, 0xfd, 0xc0, 0x1f, 0xae,
+	0x65, 0x38, 0x9c, 0x6d, 0xb0, 0x48, 0x02, 0x7d, 0x89, 0xdf, 0xf1, 0xab, 0x76, 0xf7, 0x69, 0xf7,
+	0xe9, 0xb1, 0x0d, 0xcc, 0x1c, 0x5d, 0x69, 0x51, 0x79, 0x86, 0x1b, 0xdb, 0x06, 0x92, 0xfc, 0x31,
+	0x52, 0x1a, 0x5b, 0xb8, 0x02, 0xae, 0x17, 0xea, 0x83, 0xc8, 0x9c, 0x90, 0x90, 0x35, 0x10, 0xf2,
+	0x12, 0xba, 0xce, 0x00, 0x45, 0x5b, 0xd6, 0xac, 0x87, 0xdb, 0x2a, 0xbd, 0x5b, 0xca, 0xcf, 0x8d,
+	0x67, 0x9b, 0x1f, 0xeb, 0x5a, 0x64, 0x4b, 0x6f, 0xbf, 0x5d, 0x9b, 0x71, 0x68, 0x92, 0x77, 0x31,
+	0x31, 0x7d, 0xeb, 0xde, 0x9a, 0x09, 0x2f, 0xb3, 0x02, 0x25, 0x39, 0x02, 0xb8, 0x28, 0x6b, 0x31,
+	0x47, 0x03, 0x12, 0xf7, 0x00, 0xac, 0x9f, 0xa2, 0xc1, 0xe1, 0x1a, 0x70, 0x2a, 0x93, 0x5b, 0xd7,
+	0x1d, 0xfb, 0x70, 0x1d, 0xff, 0x0b, 0x00, 0x00, 0xff, 0xff, 0xdc, 0x73, 0x61, 0x1c, 0xc9, 0x04,
+	0x00, 0x00,
+}
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ context.Context
+var _ grpc.ClientConnInterface
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the grpc package it is being compiled against.
+const _ = grpc.SupportPackageIsVersion6
+
+// HookHandlerClient is the client API for HookHandler service.
+//
+// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://godoc.org/google.golang.org/grpc#ClientConn.NewStream.
+type HookHandlerClient interface {
+	// Sends a hook
+	InvokeHook(ctx context.Context, in *HookRequest, opts ...grpc.CallOption) (*HookResponse, error)
+}
+
+type hookHandlerClient struct {
+	cc grpc.ClientConnInterface
+}
+
+func NewHookHandlerClient(cc grpc.ClientConnInterface) HookHandlerClient {
+	return &hookHandlerClient{cc}
+}
+
+func (c *hookHandlerClient) InvokeHook(ctx context.Context, in *HookRequest, opts ...grpc.CallOption) (*HookResponse, error) {
+	out := new(HookResponse)
+	err := c.cc.Invoke(ctx, "/v2.HookHandler/InvokeHook", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+// HookHandlerServer is the server API for HookHandler service.
+type HookHandlerServer interface {
+	// Sends a hook
+	InvokeHook(context.Context, *HookRequest) (*HookResponse, error)
+}
+
+// UnimplementedHookHandlerServer can be embedded to have forward compatible implementations.
+type UnimplementedHookHandlerServer struct {
+}
+
+func (*UnimplementedHookHandlerServer) InvokeHook(ctx context.Context, req *HookRequest) (*HookResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method InvokeHook not implemented")
+}
+
+func RegisterHookHandlerServer(s *grpc.Server, srv HookHandlerServer) {
+	s.RegisterService(&_HookHandler_serviceDesc, srv)
+}
+
+func _HookHandler_InvokeHook_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(HookRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(HookHandlerServer).InvokeHook(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/v2.HookHandler/InvokeHook",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(HookHandlerServer).InvokeHook(ctx, req.(*HookRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+var _HookHandler_serviceDesc = grpc.ServiceDesc{
+	ServiceName: "v2.HookHandler",
+	HandlerType: (*HookHandlerServer)(nil),
+	Methods: []grpc.MethodDesc{
+		{
+			MethodName: "InvokeHook",
+			Handler:    _HookHandler_InvokeHook_Handler,
+		},
+	},
+	Streams:  []grpc.StreamDesc{},
+	Metadata: "v2/hook.proto",
+}

pkg/s3store/s3store.go

@@ -717,7 +717,7 @@ func (upload s3Upload) GetReader(ctx context.Context) (io.Reader, error) {
 	})
 	if err == nil {
 		// The multipart upload still exists, which means we cannot download it yet
-		return nil, handler.NewHTTPError("ERR_INCOMPLETE_UPLOAD", "cannot stream non-finished upload", http.StatusBadRequest)
+		return nil, handler.NewError("ERR_INCOMPLETE_UPLOAD", "cannot stream non-finished upload", http.StatusBadRequest)
 	}
 
 	if isAwsError(err, "NoSuchUpload") {

pkg/s3store/s3store_test.go

@@ -576,7 +576,7 @@ func TestGetReaderNotFinished(t *testing.T) {
 
 	content, err := upload.GetReader(context.Background())
 	assert.Nil(content)
-	assert.Equal("cannot stream non-finished upload", err.Error())
+	assert.Equal("ERR_INCOMPLETE_UPLOAD: cannot stream non-finished upload", err.Error())
 }
 
 func TestDeclareLength(t *testing.T) {