Handle NS and NSE server wait timeouts cleanly

gRPC server-side streaming calls should be closed by returning nil so
we need to figure out what the timeout Error looks like and return nil
when it happens so we don't get logs full of spurious errors.

Signed-off-by: Toby Cabot <[email protected]>

pkg/registry/etcd/ns_server.go

@@ -94,6 +94,7 @@ func (n *etcdNSRegistryServer) Register(ctx context.Context, request *registry.N
 }
 
 func (n *etcdNSRegistryServer) watch(query *registry.NetworkServiceQuery, s registry.NetworkServiceRegistry_FindServer) error {
+	logger := log.FromContext(n.chainContext).WithField("etcdNSRegistryServer", "watch")
 	var watchErr error
 	for watchErr == nil {
 		timeoutSeconds := int64(time.Minute / time.Second)
@@ -108,6 +109,14 @@ func (n *etcdNSRegistryServer) watch(query *registry.NetworkServiceQuery, s regi
 
 		watcher.Stop()
 	}
+
+	// If the watch timed out, return nil to close the stream
+	// cleanly.
+	if errors.Is(watchErr, context.Canceled) {
+		logger.Debug("watch timed out, returning nil")
+		return nil
+	}
+	// If something else went wrong, return the error.
 	return watchErr
 }
 

pkg/registry/etcd/nse_server.go

@@ -144,6 +144,7 @@ func (n *etcdNSERegistryServer) Unregister(ctx context.Context, request *registr
 }
 
 func (n *etcdNSERegistryServer) watch(query *registry.NetworkServiceEndpointQuery, s registry.NetworkServiceEndpointRegistry_FindServer) error {
+	logger := log.FromContext(n.chainContext).WithField("etcdNSERegistryServer", "watch")
 	var watchErr error
 	for watchErr == nil {
 		timeoutSeconds := int64(time.Minute / time.Second)
@@ -158,6 +159,14 @@ func (n *etcdNSERegistryServer) watch(query *registry.NetworkServiceEndpointQuer
 
 		watcher.Stop()
 	}
+
+	// If the watch timed out, return nil to close the stream
+	// cleanly.
+	if errors.Is(watchErr, context.Canceled) {
+		logger.Debug("watch timed out, returning nil")
+		return nil
+	}
+	// If something else went wrong, return the error.
 	return watchErr
 }