feat: add etcd_debugging_lease_total gauge metric

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

server/lease/metrics.go

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

server/lease/metrics_test.go

@@ -0,0 +1,119 @@
+// 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
+	// This is a counter metric, which means it can only be incremented
+	// The metric is incremented by 10 and we check if it is 10
+	leaseGranted.Add(10)
+	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 10
+`
+	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
+	// This is a counter metric, which means it can only be incremented
+	// The metric is incremented by 10 and we check if it is 10
+	leaseRevoked.Add(10)
+	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 10
+`
+	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
+	// This is a counter metric, which means it can only be incremented
+	// The metric is incremented by 10 and we check if it is 10
+	leaseRenewed.Add(10)
+	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 10
+`
+	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
+	// This is a histogram metric, which means it can be incremented and observed
+	// The metric is incremented by 10 and we check if it is 10
+	leaseTotalTTLs.Observe(10)
+	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"} 0
+etcd_debugging_lease_ttl_total_bucket{le="2"} 0
+etcd_debugging_lease_ttl_total_bucket{le="4"} 0
+etcd_debugging_lease_ttl_total_bucket{le="8"} 0
+etcd_debugging_lease_ttl_total_bucket{le="16"} 1
+etcd_debugging_lease_ttl_total_bucket{le="32"} 1
+etcd_debugging_lease_ttl_total_bucket{le="64"} 1
+etcd_debugging_lease_ttl_total_bucket{le="128"} 1
+etcd_debugging_lease_ttl_total_bucket{le="256"} 1
+etcd_debugging_lease_ttl_total_bucket{le="512"} 1
+etcd_debugging_lease_ttl_total_bucket{le="1024"} 1
+etcd_debugging_lease_ttl_total_bucket{le="2048"} 1
+etcd_debugging_lease_ttl_total_bucket{le="4096"} 1
+etcd_debugging_lease_ttl_total_bucket{le="8192"} 1
+etcd_debugging_lease_ttl_total_bucket{le="16384"} 1
+etcd_debugging_lease_ttl_total_bucket{le="32768"} 1
+etcd_debugging_lease_ttl_total_bucket{le="65536"} 1
+etcd_debugging_lease_ttl_total_bucket{le="131072"} 1
+etcd_debugging_lease_ttl_total_bucket{le="262144"} 1
+etcd_debugging_lease_ttl_total_bucket{le="524288"} 1
+etcd_debugging_lease_ttl_total_bucket{le="1.048576e+06"} 1
+etcd_debugging_lease_ttl_total_bucket{le="2.097152e+06"} 1
+etcd_debugging_lease_ttl_total_bucket{le="4.194304e+06"} 1
+etcd_debugging_lease_ttl_total_bucket{le="8.388608e+06"} 1
+etcd_debugging_lease_ttl_total_bucket{le="+Inf"} 1
+etcd_debugging_lease_ttl_total_sum 10
+etcd_debugging_lease_ttl_total_count 1
+`
+	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 leaseTotal metric
+	// This is a gauge metric, which means it can be set to any value
+	// The metric is set to 10 and we check if it is 10
+	leaseTotal.Set(10)
+	expected := `
+# HELP etcd_debugging_lease_total The total number of active leases.
+# TYPE etcd_debugging_lease_total gauge
+etcd_debugging_lease_total 10
+`
+	err := testutil.CollectAndCompare(leaseTotal, strings.NewReader(expected))
+	require.NoError(t, err, "Collected metrics did not match expected metrics: %v", err)
+}