package main import ( "log" "os" "os/exec" "os/signal" "path/filepath" "strings" "syscall" ) const etcService = "/etc/service" func main() { log.SetFlags(0) runsvdir, err := exec.LookPath("runsvdir") if err != nil { log.Fatal(err) } sv, err := exec.LookPath("sv") if err != nil { log.Fatal(err) } if fi, err := os.Stat(etcService); err != nil { log.Fatal(err) } else if !fi.IsDir() { log.Fatalf("%s is not a directory", etcService) } if pid := os.Getpid(); pid != 1 { log.Printf("warning: I'm not PID 1, I'm PID %d", pid) } go reapAll() supervisor := cmd(runsvdir, etcService) if err := supervisor.Start(); err != nil { log.Fatal(err) } log.Printf("%s started", runsvdir) go shutdown(sv, supervisor.Process) if err := supervisor.Wait(); err != nil { log.Printf("%s exited with error: %v", runsvdir, err) } else { log.Printf("%s exited cleanly", runsvdir) } } func reapAll() { c := make(chan os.Signal) signal.Notify(c, syscall.SIGCHLD) for range c { go reapOne() } } // From https://github.com/ramr/go-reaper/blob/master/reaper.go func reapOne() { var ( ws syscall.WaitStatus pid int err error ) for { pid, err = syscall.Wait4(-1, &ws, 0, nil) if err != syscall.EINTR { break } } if err == syscall.ECHILD { return } log.Printf("reaped child process %d (%+v)", pid, ws) } type signaler interface { Signal(os.Signal) error } func shutdown(sv string, s signaler) { c := make(chan os.Signal) signal.Notify(c, syscall.SIGTERM, syscall.SIGINT) sig := <-c log.Printf("received %s", sig) matches, err := filepath.Glob(filepath.Join(etcService, "*")) if err != nil { log.Printf("when shutting down services: %v", err) return } var stopped []string for _, match := range matches { fi, err := os.Stat(match) if err != nil { log.Printf("%s: %v", match, err) continue } if !fi.IsDir() { log.Printf("%s: not a directory", match) continue } service := filepath.Base(match) stop := cmd(sv, "stop", service) if err := stop.Run(); err != nil { log.Printf("%s: %v", strings.Join(stop.Args, " "), err) continue } stopped = append(stopped, service) } log.Printf("stopped %d: %s", len(stopped), strings.Join(stopped, ", ")) log.Printf("stopping supervisor with signal %s...", sig) if err := s.Signal(sig); err != nil { log.Print(err) } log.Printf("shutdown handler exiting") } func cmd(path string, args ...string) *exec.Cmd { return &exec.Cmd{ Path: path, Args: append([]string{path}, args...), Env: os.Environ(), Stdin: os.Stdin, Stdout: os.Stdout, Stderr: os.Stderr, } }