feat: add etcd_debugging_lease_total gauge metric

Signed-off-by: Jimmy- <zhenguo251@gmail.com>

server/lease/lessor.go

@@ -303,6 +303,7 @@ func (le *lessor) Grant(id LeaseID, ttl int64) (*Lease, error) {
 
 	leaseTotalTTLs.Observe(float64(l.ttl))
 	leaseGranted.Inc()
+	leaseActive.Inc()
 
 	if le.isPrimary() {
 		item := &LeaseWithTime{id: l.ID, time: l.expiry}
@@ -351,6 +352,7 @@ func (le *lessor) Revoke(id LeaseID) error {
 	txn.End()
 
 	leaseRevoked.Inc()
+	leaseActive.Dec()
 	return nil
 }
 
@@ -812,6 +814,7 @@ func (le *lessor) initAndRecover() {
 	}
 	le.leaseExpiredNotifier.Init()
 	heap.Init(&le.leaseCheckpointHeap)
+	leaseActive.Set(float64(len(le.leaseMap)))
 
 	le.b.ForceCommit()
 }

server/lease/metrics.go

@@ -49,11 +49,19 @@ var (
 			// 1 second -> 3 months
 			Buckets: prometheus.ExponentialBuckets(1, 2, 24),
 		})
+
+	leaseActive = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: "etcd_debugging",
+		Subsystem: "lease",
+		Name:      "active",
+		Help:      "The current number of active leases.",
+	})
 )
 
 func init() {
 	prometheus.MustRegister(leaseGranted)
 	prometheus.MustRegister(leaseRevoked)
 	prometheus.MustRegister(leaseRenewed)
 	prometheus.MustRegister(leaseTotalTTLs)
+	prometheus.MustRegister(leaseActive)
 }

server/lease/metrics_test.go

@@ -0,0 +1,104 @@
+// Copyright 2022 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 lease
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus/testutil"
+	"github.com/stretchr/testify/require"
+)
+
+func TestLeaseGranted(t *testing.T) {
+	// Test the leaseGranted metric
+	expected := `
+# HELP etcd_debugging_lease_granted_total The total number of granted leases.
+# TYPE etcd_debugging_lease_granted_total counter
+etcd_debugging_lease_granted_total 218
+`
+	err := testutil.CollectAndCompare(leaseGranted, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}
+
+func TestNewLeaseRevoked(t *testing.T) {
+	// Test the leaseRevoked metric
+	expected := `
+# HELP etcd_debugging_lease_revoked_total The total number of revoked leases.
+# TYPE etcd_debugging_lease_revoked_total counter
+etcd_debugging_lease_revoked_total 1
+`
+	err := testutil.CollectAndCompare(leaseRevoked, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}
+
+func TestLeaseRenewed(t *testing.T) {
+	// Test the leaseRenewed metric
+	expected := `
+# HELP etcd_debugging_lease_renewed_total The number of renewed leases seen by the leader.
+# TYPE etcd_debugging_lease_renewed_total counter
+etcd_debugging_lease_renewed_total 2
+`
+	err := testutil.CollectAndCompare(leaseRenewed, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}
+
+func TestLeaseTotalTTLs(t *testing.T) {
+	// Test the leaseTotalTTLs metric
+	expected := `
+# HELP etcd_debugging_lease_ttl_total Bucketed histogram of lease TTLs.
+# TYPE etcd_debugging_lease_ttl_total histogram
+etcd_debugging_lease_ttl_total_bucket{le="1"} 2
+etcd_debugging_lease_ttl_total_bucket{le="2"} 3
+etcd_debugging_lease_ttl_total_bucket{le="4"} 3
+etcd_debugging_lease_ttl_total_bucket{le="8"} 7
+etcd_debugging_lease_ttl_total_bucket{le="16"} 214
+etcd_debugging_lease_ttl_total_bucket{le="32"} 215
+etcd_debugging_lease_ttl_total_bucket{le="64"} 215
+etcd_debugging_lease_ttl_total_bucket{le="128"} 218
+etcd_debugging_lease_ttl_total_bucket{le="256"} 218
+etcd_debugging_lease_ttl_total_bucket{le="512"} 218
+etcd_debugging_lease_ttl_total_bucket{le="1024"} 218
+etcd_debugging_lease_ttl_total_bucket{le="2048"} 218
+etcd_debugging_lease_ttl_total_bucket{le="4096"} 218
+etcd_debugging_lease_ttl_total_bucket{le="8192"} 218
+etcd_debugging_lease_ttl_total_bucket{le="16384"} 218
+etcd_debugging_lease_ttl_total_bucket{le="32768"} 218
+etcd_debugging_lease_ttl_total_bucket{le="65536"} 218
+etcd_debugging_lease_ttl_total_bucket{le="131072"} 218
+etcd_debugging_lease_ttl_total_bucket{le="262144"} 218
+etcd_debugging_lease_ttl_total_bucket{le="524288"} 218
+etcd_debugging_lease_ttl_total_bucket{le="1.048576e+06"} 218
+etcd_debugging_lease_ttl_total_bucket{le="2.097152e+06"} 218
+etcd_debugging_lease_ttl_total_bucket{le="4.194304e+06"} 218
+etcd_debugging_lease_ttl_total_bucket{le="8.388608e+06"} 218
+etcd_debugging_lease_ttl_total_bucket{le="+Inf"} 218
+etcd_debugging_lease_ttl_total_sum 2514
+etcd_debugging_lease_ttl_total_count 218
+`
+	err := testutil.CollectAndCompare(leaseTotalTTLs, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}
+
+func TestLeaseTotal(t *testing.T) {
+	// Test the leaseActive metric
+	expected := `
+# HELP etcd_debugging_lease_active The current number of active leases.
+# TYPE etcd_debugging_lease_active gauge
+etcd_debugging_lease_active 1
+`
+	err := testutil.CollectAndCompare(leaseActive, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}