auth: add new metric 'etcd_debugging_auth_revision'

auth/metrics.go

@@ -0,0 +1,42 @@
+// Copyright 2015 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 auth
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"sync"
+)
+
+var (
+	currentAuthRevision = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Namespace: "etcd_debugging",
+		Subsystem: "auth",
+		Name:      "revision",
+		Help:      "The current revision of auth store.",
+	},
+		func() float64 {
+			reportCurrentAuthRevMu.RLock()
+			defer reportCurrentAuthRevMu.RUnlock()
+			return reportCurrentAuthRev()
+		},
+	)
+	// overridden by auth store initialization
+	reportCurrentAuthRevMu sync.RWMutex
+	reportCurrentAuthRev   = func() float64 { return 0 }
+)
+
+func init() {
+	prometheus.MustRegister(currentAuthRevision)
+}

auth/store.go

@@ -1176,6 +1176,8 @@ func NewAuthStore(lg *zap.Logger, be backend.Backend, tp TokenProvider, bcryptCo
 		as.saveConsistentIndex(tx)
 	}
 
+	as.setupMetricsReporter()
+
 	tx.Unlock()
 	be.ForceCommit()
 
@@ -1462,3 +1464,11 @@ func (as *authStore) saveConsistentIndex(tx backend.BatchTx) {
 		}
 	}
 }
+
+func (as *authStore) setupMetricsReporter() {
+	reportCurrentAuthRevMu.Lock()
+	reportCurrentAuthRev = func() float64 {
+		return float64(as.Revision())
+	}
+	reportCurrentAuthRevMu.Unlock()
+}