PMM-4131 Added conn_pool_stats metrics.

Author: Anton Kucherov

CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [PMM-4131](https://jira.percona.com/browse/PMM-4131): Added some features from [dcu/mongodb_exporter](https://github.com/dcu/mongodb_exporter). See list below.
 - New metrics:
   - `mongodb_mongod_replset_member_*`
+  - `mongodb_connpoolstats_*`
 
 
 ### Fixed

collector/common/conn_pool_stats.go

@@ -0,0 +1,94 @@
+package collector_common
+
+import (
+	"context"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/common/log"
+	"go.mongodb.org/mongo-driver/bson"
+	"go.mongodb.org/mongo-driver/mongo"
+)
+
+// server connections -- all of these!
+var (
+	syncClientConnections = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Subsystem: "connpoolstats",
+		Name:      "connection_sync",
+		Help:      "Corresponds to the total number of client connections to mongo.",
+	})
+
+	numAScopedConnections = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Subsystem: "connpoolstats",
+		Name:      "connections_scoped_sync",
+		Help:      "Corresponds to the number of active and stored outgoing scoped synchronous connections from the current instance to other members of the sharded cluster or replica set.",
+	})
+
+	totalInUse = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Subsystem: "connpoolstats",
+		Name:      "connections_in_use",
+		Help:      "Corresponds to the total number of client connections to mongo currently in use.",
+	})
+
+	totalAvailable = prometheus.NewGauge(prometheus.GaugeOpts{
+		Namespace: Namespace,
+		Subsystem: "connpoolstats",
+		Name:      "connections_available",
+		Help:      "Corresponds to the total number of client connections to mongo that are currently available.",
+	})
+
+	totalCreatedDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(Namespace, "connpoolstats", "connections_created_total"),
+		"Corresponds to the total number of client connections to mongo created since instance start",
+		nil,
+		nil,
+	)
+)
+
+// ServerStatus keeps the data returned by the serverStatus() method.
+type ConnPoolStats struct {
+	SyncClientConnections float64 `bson:"numClientConnections"`
+	ASScopedConnections   float64 `bson:"numAScopedConnections"`
+	TotalInUse            float64 `bson:"totalInUse"`
+	TotalAvailable        float64 `bson:"totalAvailable"`
+	TotalCreated          float64 `bson:"totalCreated"`
+}
+
+// Export exports the server status to be consumed by prometheus.
+func (stats *ConnPoolStats) Export(ch chan<- prometheus.Metric) {
+	syncClientConnections.Set(stats.SyncClientConnections)
+	syncClientConnections.Collect(ch)
+
+	numAScopedConnections.Set(stats.ASScopedConnections)
+	numAScopedConnections.Collect(ch)
+
+	totalInUse.Set(stats.TotalInUse)
+	totalInUse.Collect(ch)
+
+	totalAvailable.Set(stats.TotalAvailable)
+	totalAvailable.Collect(ch)
+
+	ch <- prometheus.MustNewConstMetric(totalCreatedDesc, prometheus.CounterValue, stats.TotalCreated)
+}
+
+// Describe describes the server status for prometheus.
+func (stats *ConnPoolStats) Describe(ch chan<- *prometheus.Desc) {
+	syncClientConnections.Describe(ch)
+	numAScopedConnections.Describe(ch)
+	totalInUse.Describe(ch)
+	totalAvailable.Describe(ch)
+	ch <- totalCreatedDesc
+}
+
+// GetServerStatus returns the server status info.
+func GetConnPoolStats(client *mongo.Client) *ConnPoolStats {
+	result := &ConnPoolStats{}
+	err := client.Database("admin").RunCommand(context.TODO(), bson.D{{"connPoolStats", 1}, {"recordStats", 0}}).Decode(result)
+	if err != nil {
+		log.Error("Failed to get server status.")
+		return nil
+	}
+	return result
+}

collector/common/conn_pool_stats_test.go

@@ -0,0 +1,52 @@
+// Copyright 2017 Percona LLC
+//
+// 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 collector_common
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/percona/mongodb_exporter/testutils"
+)
+
+func TestGetConnPoolStatsDecodesFine(t *testing.T) {
+	// setup
+	t.Parallel()
+	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancel()
+
+	t.Run("mongod", func(t *testing.T) {
+		// setup
+		defaultClient := testutils.MustGetConnectedMongodClient(t, ctx)
+		defer defaultClient.Disconnect(ctx)
+		// run
+		statusDefault := GetConnPoolStats(defaultClient)
+		// test
+		assert.NotNil(t, statusDefault)
+	})
+
+	t.Run("replset", func(t *testing.T) {
+		// setup
+		replSetClient := testutils.MustGetConnectedReplSetClient(t, ctx)
+		defer replSetClient.Disconnect(ctx)
+		// run
+		statusReplSet := GetConnPoolStats(replSetClient)
+		// test
+		assert.NotNil(t, statusReplSet)
+	})
+}

collector/mongodb_collector.go

@@ -24,6 +24,7 @@ import (
 	"github.com/prometheus/common/log"
 	"go.mongodb.org/mongo-driver/mongo"
 
+	collector_common "github.com/percona/mongodb_exporter/collector/common"
 	"github.com/percona/mongodb_exporter/collector/mongod"
 	"github.com/percona/mongodb_exporter/collector/mongos"
 	"github.com/percona/mongodb_exporter/shared"
@@ -44,6 +45,7 @@ type MongodbCollectorOpts struct {
 	CollectCollectionMetrics bool
 	CollectTopMetrics        bool
 	CollectIndexUsageStats   bool
+	CollectConnPoolStats     bool
 	SocketTimeout            time.Duration
 	SyncTimeout              time.Duration
 	AuthentificationDB       string
@@ -237,7 +239,6 @@ func (exporter *MongodbCollector) scrape(ch chan<- prometheus.Metric) {
 
 func (exporter *MongodbCollector) collectMongos(client *mongo.Client, ch chan<- prometheus.Metric) {
 	log.Debug("Collecting Server Status")
-
 	serverStatus := mongos.GetServerStatus(client)
 	if serverStatus != nil {
 		serverStatus.Export(ch)
@@ -264,6 +265,14 @@ func (exporter *MongodbCollector) collectMongos(client *mongo.Client, ch chan<-
 			collStatList.Export(ch)
 		}
 	}
+
+	if exporter.Opts.CollectConnPoolStats {
+		log.Debug("Collecting ConnPoolStats Metrics")
+		connPoolStats := collector_common.GetConnPoolStats(client)
+		if connPoolStats != nil {
+			connPoolStats.Export(ch)
+		}
+	}
 }
 
 func (exporter *MongodbCollector) collectMongod(client *mongo.Client, ch chan<- prometheus.Metric) {
@@ -304,6 +313,14 @@ func (exporter *MongodbCollector) collectMongod(client *mongo.Client, ch chan<-
 			indexStatList.Export(ch)
 		}
 	}
+
+	if exporter.Opts.CollectConnPoolStats {
+		log.Debug("Collecting ConnPoolStats Metrics")
+		connPoolStats := collector_common.GetConnPoolStats(client)
+		if connPoolStats != nil {
+			connPoolStats.Export(ch)
+		}
+	}
 }
 
 func (exporter *MongodbCollector) collectMongodReplSet(client *mongo.Client, ch chan<- prometheus.Metric) {

mongodb_exporter.go

@@ -42,10 +42,11 @@ var (
 	listenAddressF = kingpin.Flag("web.listen-address", "Address to listen on for web interface and telemetry.").Default(":9216").String()
 	metricsPathF   = kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
 
-	collectDatabaseF   = kingpin.Flag("collect.database", "Enable collection of Database metrics").Bool()
-	collectCollectionF = kingpin.Flag("collect.collection", "Enable collection of Collection metrics").Bool()
-	collectTopF        = kingpin.Flag("collect.topmetrics", "Enable collection of table top metrics").Bool()
-	collectIndexUsageF = kingpin.Flag("collect.indexusage", "Enable collection of per index usage stats").Bool()
+	collectDatabaseF            = kingpin.Flag("collect.database", "Enable collection of Database metrics").Bool()
+	collectCollectionF          = kingpin.Flag("collect.collection", "Enable collection of Collection metrics").Bool()
+	collectTopF                 = kingpin.Flag("collect.topmetrics", "Enable collection of table top metrics").Bool()
+	collectIndexUsageF          = kingpin.Flag("collect.indexusage", "Enable collection of per index usage stats").Bool()
+	mongodbCollectConnPoolStats = kingpin.Flag("collect.connpoolstats", "Collect MongoDB connpoolstats").Bool()
 
 	uriF = kingpin.Flag("mongodb.uri", "MongoDB URI, format").
 		PlaceHolder("[mongodb://][user:pass@]host1[:port1][,host2[:port2],...][/database][?options]").
@@ -120,6 +121,7 @@ func main() {
 		CollectCollectionMetrics: *collectCollectionF,
 		CollectTopMetrics:        *collectTopF,
 		CollectIndexUsageStats:   *collectIndexUsageF,
+		CollectConnPoolStats:     *mongodbCollectConnPoolStats,
 		SocketTimeout:            *socketTimeoutF,
 		SyncTimeout:              *syncTimeoutF,
 		AuthentificationDB:       *authDB,

testdata/mongodb_exporter.testFlagHelp.golden

@@ -23,6 +23,7 @@ Flags:
       --collect.collection       Enable collection of Collection metrics
       --collect.topmetrics       Enable collection of table top metrics
       --collect.indexusage       Enable collection of per index usage stats
+      --collect.connpoolstats    Collect MongoDB connpoolstats
       --mongodb.uri=[mongodb://][user:pass@]host1[:port1][,host2[:port2],...][/database][?options]  
                                  MongoDB URI, format
       --mongodb.authentification-database=""  

testutils/mongo_client.go

@@ -23,3 +23,16 @@ func MustGetConnectedReplSetClient(t *testing.T, ctx context.Context) *mongo.Cli
 
 	return client
 }
+
+// MustGetConnectedMongodClient return mongo.Client instance connected to server started in single mode.
+func MustGetConnectedMongodClient(t *testing.T, ctx context.Context) *mongo.Client {
+	opts := options.Client().
+		ApplyURI("mongodb://127.0.0.1:27017/admin").
+		SetDirect(true).SetServerSelectionTimeout(time.Second)
+	client, err := mongo.Connect(ctx, opts)
+	if err != nil {
+		t.Fatal(errors.Wrap(err, "Couldn't connect to MongoDB instance"))
+	}
+
+	return client
+}