Add registry.Shutdown method for graceful shutdown of embedded registry

Signed-off-by: Robin Ketelbuters <robin.ketelbuters@gmail.com>

registry/registry.go

@@ -81,9 +81,6 @@ var tlsVersions = map[string]uint16{
 // defaultLogFormatter is the default formatter to use for logs.
 const defaultLogFormatter = "text"
 
-// this channel gets notified when process receives signal. It is global to ease unit testing
-var quit = make(chan os.Signal, 1)
-
 // HandlerFunc defines an http middleware
 type HandlerFunc func(config *configuration.Configuration, handler http.Handler) http.Handler
 
@@ -130,6 +127,7 @@ type Registry struct {
 	config *configuration.Configuration
 	app    *handlers.App
 	server *http.Server
+	quit   chan os.Signal
 }
 
 // NewRegistry creates a new registry from a context and configuration struct.
@@ -173,6 +171,7 @@ func NewRegistry(ctx context.Context, config *configuration.Configuration) (*Reg
 		app:    app,
 		config: config,
 		server: server,
+		quit:   make(chan os.Signal, 1),
 	}, nil
 }
 
@@ -313,7 +312,7 @@ func (registry *Registry) ListenAndServe() error {
 	}
 
 	// setup channel to get notified on SIGTERM signal
-	signal.Notify(quit, syscall.SIGTERM)
+	signal.Notify(registry.quit, syscall.SIGTERM)
 	serveErr := make(chan error)
 
 	// Start serving in goroutine and listen for stop signal in main thread
@@ -324,15 +323,20 @@ func (registry *Registry) ListenAndServe() error {
 	select {
 	case err := <-serveErr:
 		return err
-	case <-quit:
+	case <-registry.quit:
 		dcontext.GetLogger(registry.app).Info("stopping server gracefully. Draining connections for ", config.HTTP.DrainTimeout)
 		// shutdown the server with a grace period of configured timeout
 		c, cancel := context.WithTimeout(context.Background(), config.HTTP.DrainTimeout)
 		defer cancel()
-		return registry.server.Shutdown(c)
+		return registry.Shutdown(c)
 	}
 }
 
+// Shutdown gracefully shuts down the registry's HTTP server.
+func (registry *Registry) Shutdown(ctx context.Context) error {
+	return registry.server.Shutdown(ctx)
+}
+
 func configureDebugServer(config *configuration.Configuration) {
 	if config.HTTP.Debug.Addr != "" {
 		go func(addr string) {