github.com/noironetworks/cilium-net@v1.6.12/cilium-health/responder/main.go (about)

     1  // Copyright 2019 Authors of Cilium
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package main
    16  
    17  import (
    18  	"context"
    19  	"fmt"
    20  	"os"
    21  	"os/signal"
    22  	"syscall"
    23  
    24  	"github.com/cilium/cilium/pkg/health/probe/responder"
    25  	"github.com/cilium/cilium/pkg/pidfile"
    26  
    27  	flag "github.com/spf13/pflag"
    28  )
    29  
    30  func cancelOnSignal(cancel context.CancelFunc, sig ...os.Signal) {
    31  	c := make(chan os.Signal, 1)
    32  	signal.Notify(c, sig...)
    33  	go func() {
    34  		<-c
    35  		cancel()
    36  	}()
    37  }
    38  
    39  func main() {
    40  	var (
    41  		pidfilePath string
    42  		listen      int
    43  	)
    44  	flag.StringVar(&pidfilePath, "pidfile", "", "Write pid to the specified file")
    45  	flag.IntVar(&listen, "listen", 4240, "Port on which the responder listens")
    46  	flag.Parse()
    47  
    48  	// Shutdown gracefully to halt server and remove pidfile
    49  	ctx, cancel := context.WithCancel(context.Background())
    50  	cancelOnSignal(cancel, syscall.SIGINT, syscall.SIGHUP, syscall.SIGTERM, syscall.SIGQUIT)
    51  
    52  	srv := responder.NewServer(listen)
    53  	defer srv.Shutdown()
    54  	go func() {
    55  		if err := srv.Serve(); err != nil {
    56  			fmt.Fprintf(os.Stderr, "error while listening: %s\n", err.Error())
    57  			cancel()
    58  		}
    59  	}()
    60  
    61  	if pidfilePath != "" {
    62  		defer pidfile.Clean()
    63  		if err := pidfile.Write(pidfilePath); err != nil {
    64  			fmt.Fprintf(os.Stderr, "cannot write pidfile: %s: %s\n", pidfilePath, err.Error())
    65  			os.Exit(-1)
    66  		}
    67  	}
    68  
    69  	<-ctx.Done()
    70  }