Add collector for database/sql#DBStats (#866)

* Add collector for database/sql#DBStats

Signed-off-by: Mitsuo Heijo <mitsuo.heijo@gmail.com>

prometheus/collectors/dbstats_collector.go

@@ -0,0 +1,102 @@
+// Copyright 2021 The Prometheus 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 collectors
+
+import (
+	"database/sql"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type dbStatsCollector struct {
+	db *sql.DB
+
+	maxOpenConnections *prometheus.Desc
+
+	openConnections  *prometheus.Desc
+	inUseConnections *prometheus.Desc
+	idleConnections  *prometheus.Desc
+
+	waitCount         *prometheus.Desc
+	waitDuration      *prometheus.Desc
+	maxIdleClosed     *prometheus.Desc
+	maxIdleTimeClosed *prometheus.Desc
+	maxLifetimeClosed *prometheus.Desc
+}
+
+// NewDBStatsCollector returns a collector that exports metrics about the given *sql.DB.
+// See https://golang.org/pkg/database/sql/#DBStats for more information on stats.
+func NewDBStatsCollector(db *sql.DB, dbName string) prometheus.Collector {
+	fqName := func(name string) string {
+		return "go_sql_" + name
+	}
+	return &dbStatsCollector{
+		db: db,
+		maxOpenConnections: prometheus.NewDesc(
+			fqName("max_open_connections"),
+			"Maximum number of open connections to the database.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		openConnections: prometheus.NewDesc(
+			fqName("open_connections"),
+			"The number of established connections both in use and idle.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		inUseConnections: prometheus.NewDesc(
+			fqName("in_use_connections"),
+			"The number of connections currently in use.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		idleConnections: prometheus.NewDesc(
+			fqName("idle_connections"),
+			"The number of idle connections.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		waitCount: prometheus.NewDesc(
+			fqName("wait_count_total"),
+			"The total number of connections waited for.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		waitDuration: prometheus.NewDesc(
+			fqName("wait_duration_seconds_total"),
+			"The total time blocked waiting for a new connection.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		maxIdleClosed: prometheus.NewDesc(
+			fqName("max_idle_closed_total"),
+			"The total number of connections closed due to SetMaxIdleConns.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		maxIdleTimeClosed: prometheus.NewDesc(
+			fqName("max_idle_time_closed_total"),
+			"The total number of connections closed due to SetConnMaxIdleTime.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+		maxLifetimeClosed: prometheus.NewDesc(
+			fqName("max_lifetime_closed_total"),
+			"The total number of connections closed due to SetConnMaxLifetime.",
+			nil, prometheus.Labels{"db_name": dbName},
+		),
+	}
+}
+
+// Describe implements Collector.
+func (c *dbStatsCollector) Describe(ch chan<- *prometheus.Desc) {
+	c.describe(ch)
+}
+
+// Collect implements Collector.
+func (c *dbStatsCollector) Collect(ch chan<- prometheus.Metric) {
+	c.collect(ch)
+}

prometheus/collectors/dbstats_collector_go115.go

@@ -0,0 +1,43 @@
+// Copyright 2021 The Prometheus 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.
+
+// +build go1.15
+
+package collectors
+
+import "github.com/prometheus/client_golang/prometheus"
+
+func (c *dbStatsCollector) describe(ch chan<- *prometheus.Desc) {
+	ch <- c.maxOpenConnections
+	ch <- c.openConnections
+	ch <- c.inUseConnections
+	ch <- c.idleConnections
+	ch <- c.waitCount
+	ch <- c.waitDuration
+	ch <- c.maxIdleClosed
+	ch <- c.maxIdleTimeClosed
+	ch <- c.maxLifetimeClosed
+}
+
+func (c *dbStatsCollector) collect(ch chan<- prometheus.Metric) {
+	stats := c.db.Stats()
+	ch <- prometheus.MustNewConstMetric(c.maxOpenConnections, prometheus.GaugeValue, float64(stats.MaxOpenConnections))
+	ch <- prometheus.MustNewConstMetric(c.openConnections, prometheus.GaugeValue, float64(stats.OpenConnections))
+	ch <- prometheus.MustNewConstMetric(c.inUseConnections, prometheus.GaugeValue, float64(stats.InUse))
+	ch <- prometheus.MustNewConstMetric(c.idleConnections, prometheus.GaugeValue, float64(stats.Idle))
+	ch <- prometheus.MustNewConstMetric(c.waitCount, prometheus.CounterValue, float64(stats.WaitCount))
+	ch <- prometheus.MustNewConstMetric(c.waitDuration, prometheus.CounterValue, stats.WaitDuration.Seconds())
+	ch <- prometheus.MustNewConstMetric(c.maxIdleClosed, prometheus.CounterValue, float64(stats.MaxIdleClosed))
+	ch <- prometheus.MustNewConstMetric(c.maxIdleTimeClosed, prometheus.CounterValue, float64(stats.MaxIdleTimeClosed))
+	ch <- prometheus.MustNewConstMetric(c.maxLifetimeClosed, prometheus.CounterValue, float64(stats.MaxLifetimeClosed))
+}

prometheus/collectors/dbstats_collector_pre_go115.go

@@ -0,0 +1,41 @@
+// Copyright 2021 The Prometheus 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.
+
+// +build !go1.15
+
+package collectors
+
+import "github.com/prometheus/client_golang/prometheus"
+
+func (c *dbStatsCollector) describe(ch chan<- *prometheus.Desc) {
+	ch <- c.maxOpenConnections
+	ch <- c.openConnections
+	ch <- c.inUseConnections
+	ch <- c.idleConnections
+	ch <- c.waitCount
+	ch <- c.waitDuration
+	ch <- c.maxIdleClosed
+	ch <- c.maxLifetimeClosed
+}
+
+func (c *dbStatsCollector) collect(ch chan<- prometheus.Metric) {
+	stats := c.db.Stats()
+	ch <- prometheus.MustNewConstMetric(c.maxOpenConnections, prometheus.GaugeValue, float64(stats.MaxOpenConnections))
+	ch <- prometheus.MustNewConstMetric(c.openConnections, prometheus.GaugeValue, float64(stats.OpenConnections))
+	ch <- prometheus.MustNewConstMetric(c.inUseConnections, prometheus.GaugeValue, float64(stats.InUse))
+	ch <- prometheus.MustNewConstMetric(c.idleConnections, prometheus.GaugeValue, float64(stats.Idle))
+	ch <- prometheus.MustNewConstMetric(c.waitCount, prometheus.CounterValue, float64(stats.WaitCount))
+	ch <- prometheus.MustNewConstMetric(c.waitDuration, prometheus.CounterValue, stats.WaitDuration.Seconds())
+	ch <- prometheus.MustNewConstMetric(c.maxIdleClosed, prometheus.CounterValue, float64(stats.MaxIdleClosed))
+	ch <- prometheus.MustNewConstMetric(c.maxLifetimeClosed, prometheus.CounterValue, float64(stats.MaxLifetimeClosed))
+}

prometheus/collectors/dbstats_collector_test.go

@@ -0,0 +1,97 @@
+// Copyright 2021 The Prometheus 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 collectors
+
+import (
+	"database/sql"
+	"runtime"
+	"testing"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func TestDBStatsCollector(t *testing.T) {
+	reg := prometheus.NewRegistry()
+	{
+		db := new(sql.DB)
+		if err := reg.Register(NewDBStatsCollector(db, "db_A")); err != nil {
+			t.Fatal(err)
+		}
+	}
+	{
+		db := new(sql.DB)
+		if err := reg.Register(NewDBStatsCollector(db, "db_B")); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	mfs, err := reg.Gather()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	names := []string{
+		"go_sql_max_open_connections",
+		"go_sql_open_connections",
+		"go_sql_in_use_connections",
+		"go_sql_idle_connections",
+		"go_sql_wait_count_total",
+		"go_sql_wait_duration_seconds_total",
+		"go_sql_max_idle_closed_total",
+		"go_sql_max_lifetime_closed_total",
+	}
+	if runtime.Version() >= "go1.15" {
+		names = append(names, "go_sql_max_idle_time_closed_total")
+	}
+	type result struct {
+		found bool
+	}
+	results := make(map[string]result)
+	for _, name := range names {
+		results[name] = result{found: false}
+	}
+	for _, mf := range mfs {
+		m := mf.GetMetric()
+		if len(m) != 2 {
+			t.Errorf("expected 2 metrics bug got %d", len(m))
+		}
+		labelA := m[0].GetLabel()[0]
+		if name := labelA.GetName(); name != "db_name" {
+			t.Errorf("expected to get label \"db_name\" but got %s", name)
+		}
+		if value := labelA.GetValue(); value != "db_A" {
+			t.Errorf("expected to get value \"db_A\" but got %s", value)
+		}
+		labelB := m[1].GetLabel()[0]
+		if name := labelB.GetName(); name != "db_name" {
+			t.Errorf("expected to get label \"db_name\" but got %s", name)
+		}
+		if value := labelB.GetValue(); value != "db_B" {
+			t.Errorf("expected to get value \"db_B\" but got %s", value)
+		}
+
+		for _, name := range names {
+			if name == mf.GetName() {
+				results[name] = result{found: true}
+				break
+			}
+		}
+	}
+
+	for name, result := range results {
+		if !result.found {
+			t.Errorf("%s not found", name)
+		}
+	}
+}