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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
)
type orchestrator interface {
GetVersionedConfigJSON() ([]byte, error)
}
func newMetricsHandler(
readyServer *ReadyServer,
quickTunnelHostname string,
orchestrator orchestrator,
log *zerolog.Logger,
) *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)
})
if orchestrator != nil {
router.HandleFunc("/config", func(w http.ResponseWriter, r *http.Request) {
json, err := 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,
shutdownC <-chan struct{},
readyServer *ReadyServer,
quickTunnelHostname string,
orchestrator orchestrator,
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, orchestrator, 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)
<-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(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)
}