Not all grpc connections need metrics

GRPC client connection that node register makes as such doesn't need
metrics and hence allow connections to be made without metrics

Author: gnufied

connection/connection.go

@@ -73,6 +73,11 @@ func Connect(address string, metricsManager metrics.CSIMetricsManager, options .
 	return connect(address, metricsManager, []grpc.DialOption{grpc.WithTimeout(time.Second * 30)}, options)
 }
 
+// ConnectWithoutMetrics behaves exactly like Connect except no metrics are recorded.
+func ConnectWithoutMetrics(address string, options ...Option) (*grpc.ClientConn, error) {
+	return connect(address, nil, []grpc.DialOption{grpc.WithTimeout(time.Second * 30)}, options)
+}
+
 // Option is the type of all optional parameters for Connect.
 type Option func(o *options)
 
@@ -118,11 +123,14 @@ func connect(
 		grpc.WithInsecure(),                   // Don't use TLS, it's usually local Unix domain socket in a container.
 		grpc.WithBackoffMaxDelay(time.Second), // Retry every second after failure.
 		grpc.WithBlock(),                      // Block until connection succeeds.
-		grpc.WithChainUnaryInterceptor(
-			LogGRPC, // Log all messages.
-			ExtendedCSIMetricsManager{metricsManager}.RecordMetricsClientInterceptor, // Record metrics for each gRPC call.
-		),
 	)
+
+	interceptors := []grpc.UnaryClientInterceptor{LogGRPC}
+	if metricsManager != nil {
+		interceptors = append(interceptors, ExtendedCSIMetricsManager{metricsManager}.RecordMetricsClientInterceptor)
+	}
+	dialOptions = append(dialOptions, grpc.WithChainUnaryInterceptor(interceptors...))
+
 	unixPrefix := "unix://"
 	if strings.HasPrefix(address, "/") {
 		// It looks like filesystem path.

connection/connection_test.go

@@ -132,6 +132,21 @@ func TestConnectUnix(t *testing.T) {
 	}
 }
 
+func TestConnectWithoutMetrics(t *testing.T) {
+	tmp := tmpDir(t)
+	defer os.RemoveAll(tmp)
+	addr, stopServer := startServer(t, tmp, nil, nil, nil)
+	defer stopServer()
+
+	conn, err := ConnectWithoutMetrics("unix:///" + addr)
+	if assert.NoError(t, err, "connect with unix:/// prefix") &&
+		assert.NotNil(t, conn, "got a connection") {
+		assert.Equal(t, connectivity.Ready, conn.GetState(), "connection ready")
+		err = conn.Close()
+		assert.NoError(t, err, "closing connection")
+	}
+}
+
 func TestWaitForServer(t *testing.T) {
 	tmp := tmpDir(t)
 	defer os.RemoveAll(tmp)