137 lines
3.8 KiB
Go
137 lines
3.8 KiB
Go
/*
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Copyright 2017 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// A webserver that only serves a 404 page. Used as a default backend.
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package main
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import (
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"context"
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"flag"
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"fmt"
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"net/http"
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"os"
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"os/signal"
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"strconv"
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"syscall"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/client_golang/prometheus/promhttp"
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)
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func init() {
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// Register the summary and the histogram with Prometheus's default registry.
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prometheus.MustRegister(requestCount)
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prometheus.MustRegister(requestDuration)
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}
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func main() {
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// command line arguments
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port := flag.Int("port", 8080, "Port number to serve default backend 404 page.")
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healthPort := flag.Int("svc-port", 10254, "Port number to serve /healthz and /metrics.")
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timeout := flag.Duration("timeout", 5*time.Second, "Time in seconds to wait before forcefully terminating the server.")
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flag.Parse()
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notFound := newHTTPServer(fmt.Sprintf(":%d", *port), notFound())
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metrics := newHTTPServer(fmt.Sprintf(":%d", *healthPort), metrics())
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// start the healthz and metrics http server
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go func() {
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err := metrics.ListenAndServe()
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if err != http.ErrServerClosed {
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fmt.Fprintf(os.Stderr, "could not start healthz/metrics http server: %s\n", err)
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os.Exit(1)
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}
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}()
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// start the main http server
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go func() {
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err := notFound.ListenAndServe()
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if err != http.ErrServerClosed {
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fmt.Fprintf(os.Stderr, "could not start http server: %s\n", err)
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os.Exit(1)
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}
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}()
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waitShutdown(notFound, *timeout)
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}
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type server struct {
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mux *http.ServeMux
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}
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func (s *server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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s.mux.ServeHTTP(w, r)
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}
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func newHTTPServer(addr string, handler http.Handler) *http.Server {
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return &http.Server{
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Addr: addr,
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Handler: handler,
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ReadTimeout: 10 * time.Second,
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ReadHeaderTimeout: 10 * time.Second,
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WriteTimeout: 10 * time.Second,
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IdleTimeout: 10 * time.Second,
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}
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}
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func notFound(options ...func(*server)) *server {
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s := &server{mux: http.NewServeMux()}
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// TODO: this handler exists only to avoid breaking existing deployments
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s.mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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fmt.Fprint(w, "ok")
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})
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s.mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
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start := time.Now()
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w.WriteHeader(http.StatusNotFound)
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fmt.Fprint(w, "default backend - 404")
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duration := time.Now().Sub(start).Seconds() * 1e3
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proto := strconv.Itoa(r.ProtoMajor)
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proto = proto + "." + strconv.Itoa(r.ProtoMinor)
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requestCount.WithLabelValues(proto).Inc()
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requestDuration.WithLabelValues(proto).Observe(duration)
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})
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return s
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}
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func metrics() *server {
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s := &server{mux: http.NewServeMux()}
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s.mux.HandleFunc("/healthz", func(w http.ResponseWriter, r *http.Request) {
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w.WriteHeader(http.StatusOK)
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fmt.Fprint(w, "ok")
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})
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s.mux.Handle("/metrics", promhttp.Handler())
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return s
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}
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func waitShutdown(s *http.Server, timeout time.Duration) {
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stop := make(chan os.Signal, 1)
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signal.Notify(stop, os.Interrupt, syscall.SIGTERM)
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<-stop
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fmt.Fprintf(os.Stdout, "stopping http server...\n")
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ctx, cancel := context.WithTimeout(context.Background(), timeout)
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defer cancel()
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if err := s.Shutdown(ctx); err != nil {
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fmt.Fprintf(os.Stderr, "could not gracefully shutdown http server: %s\n", err)
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}
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}
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