package metrics import ( "context" "fmt" "net" "net/http" _ "net/http/pprof" "runtime" "sync" "time" "github.com/gorilla/mux" "github.com/prometheus/client_golang/prometheus" "github.com/prometheus/client_golang/prometheus/promhttp" "github.com/rs/zerolog" "golang.org/x/net/trace" ) const ( shutdownTimeout = time.Second * 15 startupTime = time.Millisecond * 500 ) func newMetricsHandler(readyServer *ReadyServer, quickTunnelHostname string) *mux.Router { router := mux.NewRouter() router.PathPrefix("/debug/").Handler(http.DefaultServeMux) router.Handle("/metrics", promhttp.Handler()) router.HandleFunc("/healthcheck", func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintf(w, "OK\n") }) if readyServer != nil { router.Handle("/ready", readyServer) } router.HandleFunc("/quicktunnel", func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintf(w, `{"hostname":"%s"}`, quickTunnelHostname) }) return router } func ServeMetrics( l net.Listener, shutdownC <-chan struct{}, readyServer *ReadyServer, quickTunnelHostname string, log *zerolog.Logger, ) (err error) { var wg sync.WaitGroup // Metrics port is privileged, so no need for further access control trace.AuthRequest = func(*http.Request) (bool, bool) { return true, true } // TODO: parameterize ReadTimeout and WriteTimeout. The maximum time we can // profile CPU usage depends on WriteTimeout h := newMetricsHandler(readyServer, quickTunnelHostname) server := &http.Server{ ReadTimeout: 10 * time.Second, WriteTimeout: 10 * time.Second, Handler: h, } wg.Add(1) go func() { defer wg.Done() err = server.Serve(l) }() log.Info().Msgf("Starting metrics server on %s", fmt.Sprintf("%v/metrics", l.Addr())) // server.Serve will hang if server.Shutdown is called before the server is // fully started up. So add artificial delay. time.Sleep(startupTime) <-shutdownC ctx, cancel := context.WithTimeout(context.Background(), shutdownTimeout) _ = server.Shutdown(ctx) cancel() wg.Wait() if err == http.ErrServerClosed { log.Info().Msg("Metrics server stopped") return nil } log.Err(err).Msg("Metrics server failed") return err } func RegisterBuildInfo(buildTime string, version string) { buildInfo := prometheus.NewGaugeVec( prometheus.GaugeOpts{ // Don't namespace build_info, since we want it to be consistent across all Cloudflare services Name: "build_info", Help: "Build and version information", }, []string{"goversion", "revision", "version"}, ) prometheus.MustRegister(buildInfo) buildInfo.WithLabelValues(runtime.Version(), buildTime, version).Set(1) }