mirror of
https://github.com/k3s-io/kubernetes.git
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123 lines
3.2 KiB
Go
123 lines
3.2 KiB
Go
/*
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Copyright 2020 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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package main
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import (
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"flag"
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"fmt"
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"io"
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"log"
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"os"
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"os/exec"
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"os/signal"
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"strings"
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"syscall"
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"github.com/pkg/errors"
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)
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var (
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logFilePath = flag.String("log-file", "", "If non-empty, save stdout to this file")
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alsoToStdOut = flag.Bool("also-stdout", false, "useful with log-file, log to standard output as well as the log file")
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redirectStderr = flag.Bool("redirect-stderr", true, "treat stderr same as stdout")
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)
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func main() {
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flag.Parse()
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if err := configureAndRun(); err != nil {
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log.Fatal(err)
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}
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}
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func configureAndRun() error {
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var (
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outputStream io.Writer = os.Stdout
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errStream io.Writer = os.Stderr
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)
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args := flag.Args()
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if len(args) == 0 {
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return errors.Errorf("not enough arguments to run")
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}
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if logFilePath != nil && *logFilePath != "" {
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logFile, err := os.OpenFile(*logFilePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
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if err != nil {
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return errors.Wrapf(err, "failed to create log file %v", *logFilePath)
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}
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if *alsoToStdOut {
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outputStream = io.MultiWriter(os.Stdout, logFile)
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} else {
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outputStream = logFile
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}
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}
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if *redirectStderr {
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errStream = outputStream
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}
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exe := args[0]
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var exeArgs []string
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if len(args) > 1 {
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exeArgs = args[1:]
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}
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cmd := exec.Command(exe, exeArgs...)
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cmd.Stdout = outputStream
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cmd.Stderr = errStream
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log.Printf("Running command:\n%v", cmdInfo(cmd))
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err := cmd.Start()
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if err != nil {
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return errors.Wrap(err, "starting command")
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}
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// Handle signals and shutdown process gracefully.
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go setupSigHandler(cmd.Process)
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return errors.Wrap(cmd.Wait(), "running command")
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}
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// cmdInfo generates a useful look at what the command is for printing/debug.
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func cmdInfo(cmd *exec.Cmd) string {
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return fmt.Sprintf(
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`Command env: (log-file=%v, also-stdout=%v, redirect-stderr=%v)
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Run from directory: %v
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Executable path: %v
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Args (comma-delimited): %v`, *logFilePath, *alsoToStdOut, *redirectStderr,
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cmd.Dir, cmd.Path, strings.Join(cmd.Args, ","),
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)
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}
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// setupSigHandler will forward any termination signals to the process
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func setupSigHandler(process *os.Process) {
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// terminationSignals are signals that cause the program to exit in the
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// supported platforms (linux, darwin, windows).
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terminationSignals := []os.Signal{syscall.SIGHUP, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT}
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c := make(chan os.Signal, 1)
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signal.Notify(c, terminationSignals...)
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// Block until a signal is received.
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log.Println("Now listening for interrupts")
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s := <-c
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log.Printf("Got signal: %v. Sending down to process (PID: %v)", s, process.Pid)
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if err := process.Signal(s); err != nil {
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log.Fatalf("Failed to signal process: %v", err)
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}
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log.Printf("Signalled process %v successfully.", process.Pid)
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}
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