Refactor Shutdown method so that it blocks

Just sending a signal to the quit channel leaves the embedding app with
no easy way of waiting for it to actually shutdown

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

registry/registry.go

@@ -325,16 +325,16 @@ func (registry *Registry) ListenAndServe() error {
 		return err
 	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()
 	}
 }
 
 // Shutdown gracefully shuts down the registry's HTTP server.
-func (registry *Registry) Shutdown() {
-	registry.quit <- os.Interrupt
+func (registry *Registry) Shutdown() error {
+	// shutdown the server with a grace period of configured timeout
+	c, cancel := context.WithTimeout(context.Background(), registry.config.HTTP.DrainTimeout)
+	defer cancel()
+	return registry.server.Shutdown(c)
 }
 
 func configureDebugServer(config *configuration.Configuration) {

registry/registry_test.go

@@ -103,7 +103,7 @@ func TestGracefulShutdown(t *testing.T) {
 	fmt.Fprintf(conn, "GET /v2/ ")
 
 	// send stop signal
-	registry.Shutdown()
+	registry.quit <- os.Interrupt
 	time.Sleep(100 * time.Millisecond)
 
 	// try connecting again. it shouldn't
@@ -325,7 +325,7 @@ func TestRegistrySupportedCipherSuite(t *testing.T) {
 	}
 
 	// send stop signal
-	registry.Shutdown()
+	registry.quit <- os.Interrupt
 	time.Sleep(100 * time.Millisecond)
 }
 
@@ -369,7 +369,7 @@ func TestRegistryUnsupportedCipherSuite(t *testing.T) {
 	}
 
 	// send stop signal
-	registry.Shutdown()
+	registry.quit <- os.Interrupt
 	time.Sleep(100 * time.Millisecond)
 }