Add prom metrics

cmd/registration_relay/main.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/beeper/registration-relay/internal/api"
 	"github.com/beeper/registration-relay/internal/config"
+	"github.com/beeper/registration-relay/internal/metrics"
 )
 
 var Commit,
@@ -27,6 +28,11 @@ func main() {
 		flagenv.StringEnvWithDefault("REGISTRATION_RELAY_LISTEN", ":8000"),
 		"Listen address",
 	)
+	metricsListenAddr := flag.String(
+		"metricsListen",
+		flagenv.StringEnvWithDefault("REGISTRATION_RELAY_METRICS_LISTEN", ":5000"),
+		"Metrics listen address",
+	)
 
 	flag.Parse()
 
@@ -45,6 +51,9 @@ func main() {
 
 	log.Info().Str("commit", Commit).Str("build_time", BuildTime).Msg("registration-relay starting")
 
+	metricsSrv := metrics.NewPrometheusMetricsHandler(*metricsListenAddr)
+	metricsSrv.Start()
+
 	srv := api.NewAPI(cfg)
 	srv.Start()
 
@@ -55,5 +64,6 @@ func main() {
 	log.Info().Msg("Going to stop...")
 
 	srv.Stop()
+	metricsSrv.Stop()
 	os.Exit(0)
 }

go.mod

@@ -6,13 +6,22 @@ require (
 	github.com/beeper/libserv v0.0.0-20231201123829-f6b6f7efe7a7
 	github.com/go-chi/chi/v5 v5.0.10
 	github.com/gorilla/websocket v1.5.1
+	github.com/prometheus/client_golang v1.14.0
 	github.com/rs/zerolog v1.31.0
 )
 
 require (
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.2 // indirect
+	github.com/golang/protobuf v1.5.2 // indirect
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect
+	github.com/matttproud/golang_protobuf_extensions v1.0.2 // indirect
+	github.com/prometheus/client_model v0.3.0 // indirect
+	github.com/prometheus/common v0.37.0 // indirect
+	github.com/prometheus/procfs v0.8.0 // indirect
 	github.com/rs/xid v1.5.0 // indirect
 	golang.org/x/net v0.17.0 // indirect
 	golang.org/x/sys v0.13.0 // indirect
+	google.golang.org/protobuf v1.28.1 // indirect
 )