package daemon // import "github.com/docker/docker/daemon" import ( "context" "fmt" "runtime" "strconv" "syscall" "time" containerpkg "github.com/docker/docker/container" "github.com/docker/docker/errdefs" "github.com/moby/sys/signal" "github.com/pkg/errors" "github.com/sirupsen/logrus" ) type errNoSuchProcess struct { pid int signal syscall.Signal } func (e errNoSuchProcess) Error() string { return fmt.Sprintf("cannot kill process (pid=%d) with signal %d: no such process", e.pid, e.signal) } func (errNoSuchProcess) NotFound() {} // ContainerKill sends signal to the container // If no signal is given, then Kill with SIGKILL and wait // for the container to exit. // If a signal is given, then just send it to the container and return. func (daemon *Daemon) ContainerKill(name, stopSignal string) error { var ( err error sig = syscall.SIGKILL ) if stopSignal != "" { sig, err = signal.ParseSignal(stopSignal) if err != nil { return errdefs.InvalidParameter(err) } if !signal.ValidSignalForPlatform(sig) { return errdefs.InvalidParameter(errors.Errorf("the %s daemon does not support signal %d", runtime.GOOS, sig)) } } container, err := daemon.GetContainer(name) if err != nil { return err } if sig == syscall.SIGKILL { // perform regular Kill (SIGKILL + wait()) return daemon.Kill(container) } return daemon.killWithSignal(container, sig) } // killWithSignal sends the container the given signal. This wrapper for the // host specific kill command prepares the container before attempting // to send the signal. An error is returned if the container is paused // or not running, or if there is a problem returned from the // underlying kill command. func (daemon *Daemon) killWithSignal(container *containerpkg.Container, stopSignal syscall.Signal) error { logrus.Debugf("Sending kill signal %d to container %s", stopSignal, container.ID) container.Lock() defer container.Unlock() task, err := container.GetRunningTask() if err != nil { return err } var unpause bool if container.Config.StopSignal != "" && stopSignal != syscall.SIGKILL { containerStopSignal, err := signal.ParseSignal(container.Config.StopSignal) if err != nil { return err } if containerStopSignal == stopSignal { container.ExitOnNext() unpause = container.Paused } } else { container.ExitOnNext() unpause = container.Paused } if !daemon.IsShuttingDown() { container.HasBeenManuallyStopped = true container.CheckpointTo(daemon.containersReplica) } // if the container is currently restarting we do not need to send the signal // to the process. Telling the monitor that it should exit on its next event // loop is enough if container.Restarting { return nil } if err := task.Kill(context.Background(), stopSignal); err != nil { if errdefs.IsNotFound(err) { unpause = false logrus.WithError(err).WithField("container", container.ID).WithField("action", "kill").Debug("container kill failed because of 'container not found' or 'no such process'") go func() { // We need to clean up this container but it is possible there is a case where we hit here before the exit event is processed // but after it was fired off. // So let's wait the container's stop timeout amount of time to see if the event is eventually processed. // Doing this has the side effect that if no event was ever going to come we are waiting a a longer period of time uneccessarily. // But this prevents race conditions in processing the container. ctx, cancel := context.WithTimeout(context.TODO(), time.Duration(container.StopTimeout())*time.Second) defer cancel() s := <-container.Wait(ctx, containerpkg.WaitConditionNotRunning) if s.Err() != nil { daemon.handleContainerExit(container, nil) } }() } else { return errors.Wrapf(err, "Cannot kill container %s", container.ID) } } if unpause { // above kill signal will be sent once resume is finished if err := task.Resume(context.Background()); err != nil { logrus.Warnf("Cannot unpause container %s: %s", container.ID, err) } } daemon.LogContainerEventWithAttributes(container, "kill", map[string]string{ "signal": strconv.Itoa(int(stopSignal)), }) return nil } // Kill forcefully terminates a container. func (daemon *Daemon) Kill(container *containerpkg.Container) error { if !container.IsRunning() { return errNotRunning(container.ID) } // 1. Send SIGKILL if err := daemon.killPossiblyDeadProcess(container, syscall.SIGKILL); err != nil { // kill failed, check if process is no longer running. if errors.As(err, &errNoSuchProcess{}) { return nil } } ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second) defer cancel() status := <-container.Wait(ctx, containerpkg.WaitConditionNotRunning) if status.Err() == nil { return nil } logrus.WithError(status.Err()).WithField("container", container.ID).Error("Container failed to exit within 10 seconds of kill - trying direct SIGKILL") if err := killProcessDirectly(container); err != nil { if errors.As(err, &errNoSuchProcess{}) { return nil } return err } // wait for container to exit one last time, if it doesn't then kill didnt work, so return error ctx2, cancel2 := context.WithTimeout(context.Background(), 2*time.Second) defer cancel2() if status := <-container.Wait(ctx2, containerpkg.WaitConditionNotRunning); status.Err() != nil { return errors.New("tried to kill container, but did not receive an exit event") } return nil } // killPossibleDeadProcess is a wrapper around killSig() suppressing "no such process" error. func (daemon *Daemon) killPossiblyDeadProcess(container *containerpkg.Container, sig syscall.Signal) error { err := daemon.killWithSignal(container, sig) if errdefs.IsNotFound(err) { err = errNoSuchProcess{container.GetPID(), sig} logrus.Debug(err) return err } return err }