*: expose etcdhttp.Health, define proxy health handler

Signed-off-by: Gyu-Ho Lee <gyuhox@gmail.com>

proxy/grpcproxy/health.go

@@ -0,0 +1,43 @@
+// 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 grpcproxy
+
+import (
+	"net/http"
+	"time"
+
+	"github.com/coreos/etcd/clientv3"
+	"github.com/coreos/etcd/etcdserver/api/etcdhttp"
+	"github.com/coreos/etcd/etcdserver/api/v3rpc/rpctypes"
+
+	"golang.org/x/net/context"
+)
+
+// HandleHealth registers health handler on '/health'.
+func HandleHealth(mux *http.ServeMux, c *clientv3.Client) {
+	mux.Handle(etcdhttp.PathHealth, etcdhttp.NewHealthHandler(func() etcdhttp.Health { return checkHealth(c) }))
+}
+
+func checkHealth(c *clientv3.Client) etcdhttp.Health {
+	h := etcdhttp.Health{Health: false}
+	ctx, cancel := context.WithTimeout(c.Ctx(), time.Second)
+	_, err := c.Get(ctx, "a")
+	cancel()
+	h.Health = err == nil || err == rpctypes.ErrPermissionDenied
+	if !h.Health {
+		h.Errors = append(h.Errors, err.Error())
+	}
+	return h
+}