add prometheus metrics

pkg/prom/db_stats_collector.go

@@ -0,0 +1,143 @@
+package prom
+
+import (
+	"database/sql"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const subsystem = "connections"
+
+// DBStatsGetter is an interface that gets sql.DBStats.
+type DBStatsGetter interface {
+	Stats() sql.DBStats
+}
+
+// DBStatsCollector implements the prometheus.Collector interface.
+type DBStatsCollector struct {
+	sg DBStatsGetter
+
+	// descriptions of exported metrics
+	maxOpenDesc           *prometheus.Desc
+	openDesc              *prometheus.Desc
+	inUseDesc             *prometheus.Desc
+	idleDesc              *prometheus.Desc
+	waitedForDesc         *prometheus.Desc
+	blockedSecondsDesc    *prometheus.Desc
+	closedMaxIdleDesc     *prometheus.Desc
+	closedMaxLifetimeDesc *prometheus.Desc
+}
+
+// NewDBStatsCollector creates a new DBStatsCollector.
+func NewDBStatsCollector(dbName string, sg DBStatsGetter) *DBStatsCollector {
+	labels := prometheus.Labels{"db_name": dbName}
+	return &DBStatsCollector{
+		sg: sg,
+		maxOpenDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "max_open"),
+			"Maximum number of open connections to the database.",
+			nil,
+			labels,
+		),
+		openDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "open"),
+			"The number of established connections both in use and idle.",
+			nil,
+			labels,
+		),
+		inUseDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "in_use"),
+			"The number of connections currently in use.",
+			nil,
+			labels,
+		),
+		idleDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "idle"),
+			"The number of idle connections.",
+			nil,
+			labels,
+		),
+		waitedForDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "waited_for"),
+			"The total number of connections waited for.",
+			nil,
+			labels,
+		),
+		blockedSecondsDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "blocked_seconds"),
+			"The total time blocked waiting for a new connection.",
+			nil,
+			labels,
+		),
+		closedMaxIdleDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "closed_max_idle"),
+			"The total number of connections closed due to SetMaxIdleConns.",
+			nil,
+			labels,
+		),
+		closedMaxLifetimeDesc: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, subsystem, "closed_max_lifetime"),
+			"The total number of connections closed due to SetConnMaxLifetime.",
+			nil,
+			labels,
+		),
+	}
+}
+
+// Describe implements the prometheus.Collector interface.
+func (c DBStatsCollector) Describe(ch chan<- *prometheus.Desc) {
+	ch <- c.maxOpenDesc
+	ch <- c.openDesc
+	ch <- c.inUseDesc
+	ch <- c.idleDesc
+	ch <- c.waitedForDesc
+	ch <- c.blockedSecondsDesc
+	ch <- c.closedMaxIdleDesc
+	ch <- c.closedMaxLifetimeDesc
+}
+
+// Collect implements the prometheus.Collector interface.
+func (c DBStatsCollector) Collect(ch chan<- prometheus.Metric) {
+	stats := c.sg.Stats()
+
+	ch <- prometheus.MustNewConstMetric(
+		c.maxOpenDesc,
+		prometheus.GaugeValue,
+		float64(stats.MaxOpenConnections),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.openDesc,
+		prometheus.GaugeValue,
+		float64(stats.OpenConnections),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.inUseDesc,
+		prometheus.GaugeValue,
+		float64(stats.InUse),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.idleDesc,
+		prometheus.GaugeValue,
+		float64(stats.Idle),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.waitedForDesc,
+		prometheus.CounterValue,
+		float64(stats.WaitCount),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.blockedSecondsDesc,
+		prometheus.CounterValue,
+		stats.WaitDuration.Seconds(),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.closedMaxIdleDesc,
+		prometheus.CounterValue,
+		float64(stats.MaxIdleClosed),
+	)
+	ch <- prometheus.MustNewConstMetric(
+		c.closedMaxLifetimeDesc,
+		prometheus.CounterValue,
+		float64(stats.MaxLifetimeClosed),
+	)
+}

pkg/prom/prom.go

@@ -0,0 +1,27 @@
+package prom
+
+import (
+	"github.com/jmoiron/sqlx"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+	namespace      = "ipld_eth_server"
+	statsSubsystem = "stats"
+)
+
+var (
+	metrics bool
+)
+
+// Init module initialization
+func Init() {
+	metrics = true
+}
+
+// RegisterDBCollector create metric colletor for given connection
+func RegisterDBCollector(name string, db *sqlx.DB) {
+	if metrics {
+		prometheus.Register(NewDBStatsCollector(name, db))
+	}
+}

pkg/prom/serve.go

@@ -0,0 +1,31 @@
+package prom
+
+import (
+	"errors"
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
+	"github.com/sirupsen/logrus"
+)
+
+var errPromHTTP = errors.New("can't start http server for prometheus")
+
+// Serve start listening http
+func Serve(addr string) *http.Server {
+	mux := http.NewServeMux()
+	mux.Handle("/metrics", promhttp.Handler())
+	srv := http.Server{
+		Addr:    addr,
+		Handler: mux,
+	}
+	go func() {
+		if err := srv.ListenAndServe(); err != nil {
+			logrus.
+				WithError(err).
+				WithField("module", "prom").
+				WithField("addr", addr).
+				Fatal(errPromHTTP)
+		}
+	}()
+	return &srv
+}

pkg/serve/config.go

@@ -21,6 +21,7 @@ import (
 	"path/filepath"
 
 	"github.com/vulcanize/ipld-eth-indexer/pkg/node"
+	"github.com/vulcanize/ipld-eth-server/pkg/prom"
 
 	"github.com/spf13/viper"
 
@@ -81,6 +82,7 @@ func NewConfig() (*Config, error) {
 	c.HTTPEndpoint = httpPath
 	overrideDBConnConfig(&c.DBConfig)
 	serveDB := utils.LoadPostgres(c.DBConfig, node.Info{})
+	prom.RegisterDBCollector(c.DBConfig.Name, serveDB.DB)
 	c.DB = &serveDB
 
 	return c, nil