clientv3: configurable grpc logger

clientv3/client.go

@@ -17,6 +17,8 @@ package clientv3
 import (
 	"crypto/tls"
 	"errors"
+	"io/ioutil"
+	"log"
 	"net"
 	"net/url"
 	"strings"
@@ -26,6 +28,7 @@ import (
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
+	"google.golang.org/grpc/grpclog"
 )
 
 var (
@@ -49,6 +52,8 @@ type Client struct {
 
 	ctx    context.Context
 	cancel context.CancelFunc
+
+	logger grpclog.Logger
 }
 
 // EndpointDialer is a policy for choosing which endpoint to dial next
@@ -66,6 +71,10 @@ type Config struct {
 
 	// TLS holds the client secure credentials, if any.
 	TLS *tls.Config
+
+	// Logger defines client-sider log interface.
+	// If Logger is nil, logging will be ignored, including gRPC log.
+	Logger grpclog.Logger
 }
 
 // New creates a new etcdv3 client from a given configuration.
@@ -180,6 +189,15 @@ func newClient(cfg *Config) (*Client, error) {
 	client.Watcher = NewWatcher(client)
 	client.Auth = NewAuth(client)
 	client.Maintenance = &maintenance{c: client}
+	if cfg.Logger == nil {
+		// same as default std logger
+		client.logger = log.New(ioutil.Discard, "", 0)
+		// disable client side grpc by default
+		grpclog.SetLogger(log.New(ioutil.Discard, "", 0))
+	} else {
+		client.logger = cfg.Logger
+		grpclog.SetLogger(cfg.Logger)
+	}
 
 	return client, nil
 }