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package daemon
import (
"context"
"fmt"
"runtime"
"syscall"
"time"
"github.com/docker/docker/api/errdefs"
containerpkg "github.com/docker/docker/container"
"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)
}
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