cli: add header forwarding in HTTP hooks (#371)

* cli: add header forwarding in HTTP hooks

* docs: Reword header forwarding flag, add documentation

cmd/tusd/cli/flags.go

@@ -9,34 +9,35 @@ import (
 )
 
 var Flags struct {
-	HttpHost            string
-	HttpPort            string
-	HttpSock            string
-	MaxSize             int64
-	UploadDir           string
-	Basepath            string
-	Timeout             int64
-	S3Bucket            string
-	S3ObjectPrefix      string
-	S3Endpoint          string
-	GCSBucket           string
-	GCSObjectPrefix     string
-	EnabledHooksString  string
-	FileHooksDir        string
-	HttpHooksEndpoint   string
-	HttpHooksRetry      int
-	HttpHooksBackoff    int
-	GrpcHooksEndpoint   string
-	GrpcHooksRetry      int
-	GrpcHooksBackoff    int
-	HooksStopUploadCode int
-	PluginHookPath      string
-	EnabledHooks        []hooks.HookType
-	ShowVersion         bool
-	ExposeMetrics       bool
-	MetricsPath         string
-	BehindProxy         bool
-	VerboseOutput       bool
+	HttpHost                string
+	HttpPort                string
+	HttpSock                string
+	MaxSize                 int64
+	UploadDir               string
+	Basepath                string
+	Timeout                 int64
+	S3Bucket                string
+	S3ObjectPrefix          string
+	S3Endpoint              string
+	GCSBucket               string
+	GCSObjectPrefix         string
+	EnabledHooksString      string
+	FileHooksDir            string
+	HttpHooksEndpoint       string
+	HttpHooksForwardHeaders string
+	HttpHooksRetry          int
+	HttpHooksBackoff        int
+	GrpcHooksEndpoint       string
+	GrpcHooksRetry          int
+	GrpcHooksBackoff        int
+	HooksStopUploadCode     int
+	PluginHookPath          string
+	EnabledHooks            []hooks.HookType
+	ShowVersion             bool
+	ExposeMetrics           bool
+	MetricsPath             string
+	BehindProxy             bool
+	VerboseOutput           bool
 }
 
 func ParseFlags() {
@@ -55,6 +56,7 @@ func ParseFlags() {
 	flag.StringVar(&Flags.EnabledHooksString, "hooks-enabled-events", "", "Comma separated list of enabled hook events (e.g. post-create,post-finish). Leave empty to enable all events")
 	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")
 	flag.IntVar(&Flags.HttpHooksRetry, "hooks-http-retry", 3, "Number of times to retry on a 500 or network timeout")
 	flag.IntVar(&Flags.HttpHooksBackoff, "hooks-http-backoff", 1, "Number of seconds to wait before retrying each retry")
 	flag.StringVar(&Flags.GrpcHooksEndpoint, "hooks-grpc", "", "An gRPC endpoint to which hook events will be sent to")

cmd/tusd/cli/hooks.go

@@ -54,9 +54,10 @@ func SetupPreHooks(config *handler.Config) error {
 		stdout.Printf("Using '%s' as the endpoint for hooks", Flags.HttpHooksEndpoint)
 
 		hookHandler = &hooks.HttpHook{
-			Endpoint:   Flags.HttpHooksEndpoint,
-			MaxRetries: Flags.HttpHooksRetry,
-			Backoff:    Flags.HttpHooksBackoff,
+			Endpoint:       Flags.HttpHooksEndpoint,
+			MaxRetries:     Flags.HttpHooksRetry,
+			Backoff:        Flags.HttpHooksBackoff,
+			ForwardHeaders: strings.Split(Flags.HttpHooksForwardHeaders, ","),
 		}
 	} else if Flags.GrpcHooksEndpoint != "" {
 		stdout.Printf("Using '%s' as the endpoint for gRPC hooks", Flags.GrpcHooksEndpoint)

cmd/tusd/cli/hooks/http.go

@@ -14,9 +14,10 @@ import (
 )
 
 type HttpHook struct {
-	Endpoint   string
-	MaxRetries int
-	Backoff    int
+	Endpoint       string
+	MaxRetries     int
+	Backoff        int
+	ForwardHeaders []string
 }
 
 func (_ HttpHook) Setup() error {
@@ -34,6 +35,14 @@ func (h HttpHook) InvokeHook(typ HookType, info handler.HookEvent, captureOutput
 		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")
 

docs/hooks.md

@@ -137,6 +137,8 @@ Note that the URL must include the `http://` prefix!
 
 In case of a blocking hook, HTTP Status Code 400 or greater tells tusd to reject the request (in the same way as non-zero exit code for File Hooks). See also [issue #170](https://github.com/tus/tusd/issues/170) regarding further improvements.
 
+Headers from the client's upload request can be copied to the hook request with the `-hooks-http-forward-headers` flag.
+This is particularly useful for including authentication headers such as `Authorization` or `Cookie`.
 
 ### Usage