[3.4] Backport healthcheck code cleanup

embed/etcd.go

@@ -773,6 +773,8 @@ func (e *Etcd) serveClients() (err error) {
 	} else {
 		mux := http.NewServeMux()
 		etcdhttp.HandleBasic(mux, e.Server)
+		etcdhttp.HandleMetrics(mux)
+		etcdhttp.HandleHealth(mux, e.Server)
 		h = mux
 	}
 
@@ -861,7 +863,8 @@ func (e *Etcd) serveMetrics() (err error) {
 
 	if len(e.cfg.ListenMetricsUrls) > 0 {
 		metricsMux := http.NewServeMux()
-		etcdhttp.HandleMetricsHealth(metricsMux, e.Server)
+		etcdhttp.HandleMetrics(metricsMux)
+		etcdhttp.HandleHealth(metricsMux, e.Server)
 
 		for _, murl := range e.cfg.ListenMetricsUrls {
 			tlsInfo := &e.cfg.ClientTLSInfo

etcdmain/etcd.go

@@ -542,7 +542,7 @@ func startProxy(cfg *config) error {
 				plog.Infof("v2 proxy started listening on client requests on %q", host)
 			}
 			mux := http.NewServeMux()
-			etcdhttp.HandlePrometheus(mux) // v2 proxy just uses the same port
+			etcdhttp.HandleMetrics(mux) // v2 proxy just uses the same port
 			mux.Handle("/", ph)
 			plog.Fatal(http.Serve(l, mux))
 		}()

etcdserver/api/etcdhttp/base.go

@@ -51,7 +51,6 @@ func HandleBasic(mux *http.ServeMux, server etcdserver.ServerPeer) {
 	// TODO: deprecate '/config/local/log' in v3.5
 	mux.HandleFunc(configPath+"/local/log", logHandleFunc)
 
-	HandleMetricsHealth(mux, server)
 	mux.HandleFunc(versionPath, versionHandler(server.Cluster(), serveVersion))
 }
 

etcdserver/api/etcdhttp/health.go

@@ -0,0 +1,223 @@
+// 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 etcdhttp
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"go.etcd.io/etcd/auth"
+	"go.etcd.io/etcd/etcdserver"
+	pb "go.etcd.io/etcd/etcdserver/etcdserverpb"
+	"go.etcd.io/etcd/pkg/types"
+	"go.etcd.io/etcd/raft"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	PathHealth = "/health"
+)
+
+type ServerHealth interface {
+	serverHealthV2V3
+	Range(context.Context, *pb.RangeRequest) (*pb.RangeResponse, error)
+	Config() etcdserver.ServerConfig
+}
+
+type serverHealthV2V3 interface {
+	Alarms() []*pb.AlarmMember
+	Leader() types.ID
+}
+
+// HandleHealthForV2 registers metrics and health handlers for v2.
+func HandleHealthForV2(mux *http.ServeMux, srv etcdserver.ServerV2) {
+	mux.Handle(PathHealth, NewHealthHandler(func(excludedAlarms AlarmSet, serializable bool) Health {
+		if h := checkAlarms(srv, excludedAlarms); h.Health != "true" {
+			return h
+		}
+		if h := checkLeader(srv, serializable); h.Health != "true" {
+			return h
+		}
+		return checkV2API(srv)
+	}))
+}
+
+// HandleHealth registers metrics and health handlers. it checks health by using v3 range request
+// and its corresponding timeout.
+func HandleHealth(mux *http.ServeMux, srv ServerHealth) {
+	mux.Handle(PathHealth, NewHealthHandler(func(excludedAlarms AlarmSet, serializable bool) Health {
+		if h := checkAlarms(srv, excludedAlarms); h.Health != "true" {
+			return h
+		}
+		if h := checkLeader(srv, serializable); h.Health != "true" {
+			return h
+		}
+		return checkAPI(srv, serializable)
+	}))
+}
+
+// NewHealthHandler handles '/health' requests.
+func NewHealthHandler(hfunc func(excludedAlarms AlarmSet, serializable bool) Health) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			w.Header().Set("Allow", http.MethodGet)
+			http.Error(w, "Method Not Allowed", http.StatusMethodNotAllowed)
+			plog.Warningf("/health error (status code %d)", http.StatusMethodNotAllowed)
+			return
+		}
+		excludedAlarms := getExcludedAlarms(r)
+		// Passing the query parameter "serializable=true" ensures that the
+		// health of the local etcd is checked vs the health of the cluster.
+		// This is useful for probes attempting to validate the liveness of
+		// the etcd process vs readiness of the cluster to serve requests.
+		serializableFlag := getSerializableFlag(r)
+		h := hfunc(excludedAlarms, serializableFlag)
+		defer func() {
+			if h.Health == "true" {
+				healthSuccess.Inc()
+			} else {
+				healthFailed.Inc()
+			}
+		}()
+		d, _ := json.Marshal(h)
+		if h.Health != "true" {
+			http.Error(w, string(d), http.StatusServiceUnavailable)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		w.Write(d)
+		plog.Debugf("/health OK (status code %d)", http.StatusOK)
+	}
+}
+
+var (
+	healthSuccess = prometheus.NewCounter(prometheus.CounterOpts{
+		Namespace: "etcd",
+		Subsystem: "server",
+		Name:      "health_success",
+		Help:      "The total number of successful health checks",
+	})
+	healthFailed = prometheus.NewCounter(prometheus.CounterOpts{
+		Namespace: "etcd",
+		Subsystem: "server",
+		Name:      "health_failures",
+		Help:      "The total number of failed health checks",
+	})
+)
+
+func init() {
+	prometheus.MustRegister(healthSuccess)
+	prometheus.MustRegister(healthFailed)
+}
+
+// Health defines etcd server health status.
+// TODO: remove manual parsing in etcdctl cluster-health
+type Health struct {
+	Health string `json:"health"`
+	Reason string `json:"-"`
+}
+
+type AlarmSet map[string]struct{}
+
+func getExcludedAlarms(r *http.Request) (alarms AlarmSet) {
+	alarms = make(map[string]struct{}, 2)
+	alms, found := r.URL.Query()["exclude"]
+	if found {
+		for _, alm := range alms {
+			if len(alms) == 0 {
+				continue
+			}
+			alarms[alm] = struct{}{}
+		}
+	}
+	return alarms
+}
+
+func getSerializableFlag(r *http.Request) bool {
+	return r.URL.Query().Get("serializable") == "true"
+}
+
+// TODO: etcdserver.ErrNoLeader in health API
+
+func checkAlarms(srv serverHealthV2V3, excludedAlarms AlarmSet) Health {
+	h := Health{Health: "true"}
+	as := srv.Alarms()
+	if len(as) > 0 {
+		for _, v := range as {
+			alarmName := v.Alarm.String()
+			if _, found := excludedAlarms[alarmName]; found {
+				plog.Debugf("/health excluded alarm %s", v.String())
+				continue
+			}
+
+			h.Health = "false"
+			switch v.Alarm {
+			case pb.AlarmType_NOSPACE:
+				h.Reason = "ALARM NOSPACE"
+			case pb.AlarmType_CORRUPT:
+				h.Reason = "ALARM CORRUPT"
+			default:
+				h.Reason = "ALARM UNKNOWN"
+			}
+			plog.Warningf("/health error due to %s", v.String())
+			return h
+		}
+	}
+
+	return h
+}
+
+func checkLeader(srv serverHealthV2V3, serializable bool) Health {
+	h := Health{Health: "true"}
+	if !serializable && (uint64(srv.Leader()) == raft.None) {
+		h.Health = "false"
+		h.Reason = "RAFT NO LEADER"
+		plog.Warningf("/health error; no leader (status code %d)", http.StatusServiceUnavailable)
+	}
+	return h
+}
+
+func checkV2API(srv etcdserver.ServerV2) Health {
+	h := Health{Health: "true"}
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
+	_, err := srv.Do(ctx, pb.Request{Method: "QGET"})
+	cancel()
+	if err != nil {
+		h.Health = "false"
+		h.Reason = fmt.Sprintf("QGET ERROR:%s", err)
+		plog.Warningf("/health error; QGET failed %v (status code %d)", err, http.StatusServiceUnavailable)
+		return h
+	}
+	return h
+}
+
+func checkAPI(srv ServerHealth, serializable bool) Health {
+	h := Health{Health: "true"}
+	cfg := srv.Config()
+	ctx, cancel := context.WithTimeout(context.Background(), cfg.ReqTimeout())
+	_, err := srv.Range(ctx, &pb.RangeRequest{KeysOnly: true, Limit: 1, Serializable: serializable})
+	cancel()
+	if err != nil && err != auth.ErrUserEmpty && err != auth.ErrPermissionDenied {
+		h.Health = "false"
+		h.Reason = fmt.Sprintf("RANGE ERROR:%s", err)
+		plog.Warningf("serving /health false; Range failed %v (status code %d)", err, http.StatusServiceUnavailable)
+		return h
+	}
+	return h
+}