*: add basic health check service

etcdserver/api/v3rpc/grpc.go

@@ -19,9 +19,12 @@ import (
 
 	"github.com/coreos/etcd/etcdserver"
 	pb "github.com/coreos/etcd/etcdserver/etcdserverpb"
+
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials"
 	"google.golang.org/grpc/grpclog"
+	"google.golang.org/grpc/health"
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
 )
 
 const grpcOverheadBytes = 512 * 1024
@@ -48,5 +51,12 @@ func Server(s *etcdserver.EtcdServer, tls *tls.Config) *grpc.Server {
 	pb.RegisterAuthServer(grpcServer, NewAuthServer(s))
 	pb.RegisterMaintenanceServer(grpcServer, NewMaintenanceServer(s))
 
+	// server should register all the services manually
+	// use empty service name for all etcd services' health status,
+	// see https://github.com/grpc/grpc/blob/master/doc/health-checking.md for more
+	hsrv := health.NewServer()
+	hsrv.SetServingStatus("", healthpb.HealthCheckResponse_SERVING)
+	healthpb.RegisterHealthServer(grpcServer, hsrv)
+
 	return grpcServer
 }

glide.yaml

@@ -107,6 +107,8 @@ import:
   - naming
   - peer
   - transport
+  - health
+  - health/grpc_health_v1
 - package: gopkg.in/cheggaaa/pb.v1
   version: v1.0.2
 - package: gopkg.in/yaml.v2

integration/v3_health_test.go

@@ -0,0 +1,40 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package integration
+
+import (
+	"context"
+	"testing"
+
+	"github.com/coreos/etcd/pkg/testutil"
+
+	healthpb "google.golang.org/grpc/health/grpc_health_v1"
+)
+
+func TestHealthCheck(t *testing.T) {
+	defer testutil.AfterTest(t)
+
+	clus := NewClusterV3(t, &ClusterConfig{Size: 1})
+	defer clus.Terminate(t)
+
+	cli := healthpb.NewHealthClient(clus.RandClient().ActiveConnection())
+	resp, err := cli.Check(context.TODO(), &healthpb.HealthCheckRequest{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.Status != healthpb.HealthCheckResponse_SERVING {
+		t.Fatalf("status expected %s, got %s", healthpb.HealthCheckResponse_SERVING, resp.Status)
+	}
+}