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

@@ -24,6 +24,7 @@ var Flags struct {
 	EnabledHooksString      string
 	FileHooksDir            string
 	HttpHooksEndpoint       string
+	HttpHooksForwardHeaders string
 	HttpHooksRetry          int
 	HttpHooksBackoff        int
 	GrpcHooksEndpoint       string
@@ -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

@@ -57,6 +57,7 @@ func SetupPreHooks(config *handler.Config) error {
 			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

@@ -17,6 +17,7 @@ type HttpHook struct {
 	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