package metrics import ( "context" "fmt" "net" "net/http" _ "net/http/pprof" "runtime" "sync" "time" "github.com/prometheus/client_golang/prometheus" "github.com/prometheus/client_golang/prometheus/promhttp" "github.com/rs/zerolog" "golang.org/x/net/trace" ) const ( startupTime = time.Millisecond * 500 defaultShutdownTimeout = time.Second * 15 ) type Config struct { ReadyServer *ReadyServer QuickTunnelHostname string Orchestrator orchestrator ShutdownTimeout time.Duration } type orchestrator interface { GetVersionedConfigJSON() ([]byte, error) } func newMetricsHandler( config Config, log *zerolog.Logger, ) *http.ServeMux { router := http.NewServeMux() router.Handle("/metrics", promhttp.Handler()) router.HandleFunc("/healthcheck", func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintf(w, "OK\n") }) if config.ReadyServer != nil { router.Handle("/ready", config.ReadyServer) } router.HandleFunc("/quicktunnel", func(w http.ResponseWriter, r *http.Request) { _, _ = fmt.Fprintf(w, `{"hostname":"%s"}`, config.QuickTunnelHostname) }) if config.Orchestrator != nil { router.HandleFunc("/config", func(w http.ResponseWriter, r *http.Request) { json, err := config.Orchestrator.GetVersionedConfigJSON() if err != nil { w.WriteHeader(500) _, _ = fmt.Fprintf(w, "ERR: %v", err) log.Err(err).Msg("Failed to serve config") return } _, _ = w.Write(json) }) } return router } func ServeMetrics( l net.Listener, ctx context.Context, config Config, 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(config, log) 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) <-ctx.Done() shutdownTimeout := config.ShutdownTimeout if shutdownTimeout == 0 { shutdownTimeout = defaultShutdownTimeout } 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(buildType, buildTime, 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", "type", "revision", "version"}, ) prometheus.MustRegister(buildInfo) buildInfo.WithLabelValues(runtime.Version(), buildType, buildTime, version).Set(1) }