package daemon // import "github.com/docker/docker/daemon" import ( "context" "fmt" "runtime" "syscall" "time" containerpkg "github.com/docker/docker/container" "github.com/docker/docker/errdefs" "github.com/docker/docker/libcontainerd" "github.com/docker/docker/pkg/signal" "github.com/pkg/errors" "github.com/sirupsen/logrus" ) type errNoSuchProcess struct { pid int signal int } 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() {} // isErrNoSuchProcess returns true if the error // is an instance of errNoSuchProcess. func isErrNoSuchProcess(err error) bool { _, ok := err.(errNoSuchProcess) return ok } // ContainerKill sends signal to the container // If no signal is given (sig 0), 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 string, sig uint64) error { container, err := daemon.GetContainer(name) if err != nil { return err } if sig != 0 && !signal.ValidSignalForPlatform(syscall.Signal(sig)) { return fmt.Errorf("The %s daemon does not support signal %d", runtime.GOOS, sig) } // If no signal is passed, or SIGKILL, perform regular Kill (SIGKILL + wait()) if sig == 0 || syscall.Signal(sig) == syscall.SIGKILL { return daemon.Kill(container) } return daemon.killWithSignal(container, int(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, sig int) error { logrus.Debugf("Sending kill signal %d to container %s", sig, container.ID) container.Lock() defer container.Unlock() daemon.stopHealthchecks(container) if !container.Running { return errNotRunning(container.ID) } var unpause bool if container.Config.StopSignal != "" && syscall.Signal(sig) != syscall.SIGKILL { containerStopSignal, err := signal.ParseSignal(container.Config.StopSignal) if err != nil { return err } if containerStopSignal == syscall.Signal(sig) { container.ExitOnNext() unpause = container.Paused } } else { container.ExitOnNext() unpause = container.Paused } if !daemon.IsShuttingDown() { container.HasBeenManuallyStopped = true } // 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 := daemon.kill(container, sig); 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'") } 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 := daemon.containerd.Resume(context.Background(), container.ID); err != nil { logrus.Warn("Cannot unpause container %s: %s", container.ID, err) } } attributes := map[string]string{ "signal": fmt.Sprintf("%d", sig), } daemon.LogContainerEventWithAttributes(container, "kill", attributes) 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, int(syscall.SIGKILL)); err != nil { // While normally we might "return err" here we're not going to // because if we can't stop the container by this point then // it's probably because it's already stopped. Meaning, between // the time of the IsRunning() call above and now it stopped. // Also, since the err return will be environment specific we can't // look for any particular (common) error that would indicate // that the process is already dead vs something else going wrong. // So, instead we'll give it up to 2 more seconds to complete and if // by that time the container is still running, then the error // we got is probably valid and so we return it to the caller. if isErrNoSuchProcess(err) { return nil } ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second) defer cancel() if status := <-container.Wait(ctx, containerpkg.WaitConditionNotRunning); status.Err() != nil { return err } } // 2. Wait for the process to die, in last resort, try to kill the process directly if err := killProcessDirectly(container); err != nil { if isErrNoSuchProcess(err) { return nil } return err } // Wait for exit with no timeout. // Ignore returned status. <-container.Wait(context.Background(), containerpkg.WaitConditionNotRunning) return nil } // killPossibleDeadProcess is a wrapper around killSig() suppressing "no such process" error. func (daemon *Daemon) killPossiblyDeadProcess(container *containerpkg.Container, sig int) error { err := daemon.killWithSignal(container, sig) if errdefs.IsNotFound(err) { e := errNoSuchProcess{container.GetPID(), sig} logrus.Debug(e) return e } return err } func (daemon *Daemon) kill(c *containerpkg.Container, sig int) error { return daemon.containerd.SignalProcess(context.Background(), c.ID, libcontainerd.InitProcessName, sig) }