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This PR adds support for user-defined health-check probes for Docker containers. It adds a `HEALTHCHECK` instruction to the Dockerfile syntax plus some corresponding "docker run" options. It can be used with a restart policy to automatically restart a container if the check fails. The `HEALTHCHECK` instruction has two forms: * `HEALTHCHECK [OPTIONS] CMD command` (check container health by running a command inside the container) * `HEALTHCHECK NONE` (disable any healthcheck inherited from the base image) The `HEALTHCHECK` instruction tells Docker how to test a container to check that it is still working. This can detect cases such as a web server that is stuck in an infinite loop and unable to handle new connections, even though the server process is still running. When a container has a healthcheck specified, it has a _health status_ in addition to its normal status. This status is initially `starting`. Whenever a health check passes, it becomes `healthy` (whatever state it was previously in). After a certain number of consecutive failures, it becomes `unhealthy`. The options that can appear before `CMD` are: * `--interval=DURATION` (default: `30s`) * `--timeout=DURATION` (default: `30s`) * `--retries=N` (default: `1`) The health check will first run **interval** seconds after the container is started, and then again **interval** seconds after each previous check completes. If a single run of the check takes longer than **timeout** seconds then the check is considered to have failed. It takes **retries** consecutive failures of the health check for the container to be considered `unhealthy`. There can only be one `HEALTHCHECK` instruction in a Dockerfile. If you list more than one then only the last `HEALTHCHECK` will take effect. The command after the `CMD` keyword can be either a shell command (e.g. `HEALTHCHECK CMD /bin/check-running`) or an _exec_ array (as with other Dockerfile commands; see e.g. `ENTRYPOINT` for details). The command's exit status indicates the health status of the container. The possible values are: - 0: success - the container is healthy and ready for use - 1: unhealthy - the container is not working correctly - 2: starting - the container is not ready for use yet, but is working correctly If the probe returns 2 ("starting") when the container has already moved out of the "starting" state then it is treated as "unhealthy" instead. For example, to check every five minutes or so that a web-server is able to serve the site's main page within three seconds: HEALTHCHECK --interval=5m --timeout=3s \ CMD curl -f http://localhost/ || exit 1 To help debug failing probes, any output text (UTF-8 encoded) that the command writes on stdout or stderr will be stored in the health status and can be queried with `docker inspect`. Such output should be kept short (only the first 4096 bytes are stored currently). When the health status of a container changes, a `health_status` event is generated with the new status. The health status is also displayed in the `docker ps` output. Signed-off-by: Thomas Leonard <thomas.leonard@docker.com> Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
156 lines
4.1 KiB
Go
156 lines
4.1 KiB
Go
package daemon
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import (
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"errors"
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"fmt"
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"io"
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"runtime"
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"strconv"
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"github.com/Sirupsen/logrus"
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"github.com/docker/docker/libcontainerd"
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"github.com/docker/docker/runconfig"
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)
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// StateChanged updates daemon state changes from containerd
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func (daemon *Daemon) StateChanged(id string, e libcontainerd.StateInfo) error {
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c := daemon.containers.Get(id)
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if c == nil {
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return fmt.Errorf("no such container: %s", id)
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}
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switch e.State {
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case libcontainerd.StateOOM:
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// StateOOM is Linux specific and should never be hit on Windows
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if runtime.GOOS == "windows" {
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return errors.New("Received StateOOM from libcontainerd on Windows. This should never happen.")
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}
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daemon.updateHealthMonitor(c)
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daemon.LogContainerEvent(c, "oom")
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case libcontainerd.StateExit:
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c.Lock()
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defer c.Unlock()
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c.Wait()
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c.Reset(false)
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c.SetStopped(platformConstructExitStatus(e))
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attributes := map[string]string{
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"exitCode": strconv.Itoa(int(e.ExitCode)),
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}
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daemon.updateHealthMonitor(c)
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daemon.LogContainerEventWithAttributes(c, "die", attributes)
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daemon.Cleanup(c)
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// FIXME: here is race condition between two RUN instructions in Dockerfile
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// because they share same runconfig and change image. Must be fixed
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// in builder/builder.go
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if err := c.ToDisk(); err != nil {
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return err
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}
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return daemon.postRunProcessing(c, e)
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case libcontainerd.StateRestart:
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c.Lock()
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defer c.Unlock()
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c.Reset(false)
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c.RestartCount++
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c.SetRestarting(platformConstructExitStatus(e))
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attributes := map[string]string{
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"exitCode": strconv.Itoa(int(e.ExitCode)),
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}
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daemon.LogContainerEventWithAttributes(c, "die", attributes)
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daemon.updateHealthMonitor(c)
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return c.ToDisk()
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case libcontainerd.StateExitProcess:
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c.Lock()
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defer c.Unlock()
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if execConfig := c.ExecCommands.Get(e.ProcessID); execConfig != nil {
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ec := int(e.ExitCode)
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execConfig.ExitCode = &ec
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execConfig.Running = false
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execConfig.Wait()
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if err := execConfig.CloseStreams(); err != nil {
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logrus.Errorf("%s: %s", c.ID, err)
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}
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// remove the exec command from the container's store only and not the
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// daemon's store so that the exec command can be inspected.
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c.ExecCommands.Delete(execConfig.ID)
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} else {
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logrus.Warnf("Ignoring StateExitProcess for %v but no exec command found", e)
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}
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case libcontainerd.StateStart, libcontainerd.StateRestore:
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// Container is already locked in this case
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c.SetRunning(int(e.Pid), e.State == libcontainerd.StateStart)
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c.HasBeenManuallyStopped = false
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if err := c.ToDisk(); err != nil {
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c.Reset(false)
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return err
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}
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daemon.initHealthMonitor(c)
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daemon.LogContainerEvent(c, "start")
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case libcontainerd.StatePause:
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// Container is already locked in this case
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c.Paused = true
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daemon.updateHealthMonitor(c)
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daemon.LogContainerEvent(c, "pause")
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case libcontainerd.StateResume:
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// Container is already locked in this case
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c.Paused = false
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daemon.updateHealthMonitor(c)
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daemon.LogContainerEvent(c, "unpause")
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}
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return nil
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}
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// AttachStreams is called by libcontainerd to connect the stdio.
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func (daemon *Daemon) AttachStreams(id string, iop libcontainerd.IOPipe) error {
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var s *runconfig.StreamConfig
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c := daemon.containers.Get(id)
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if c == nil {
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ec, err := daemon.getExecConfig(id)
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if err != nil {
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return fmt.Errorf("no such exec/container: %s", id)
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}
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s = ec.StreamConfig
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} else {
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s = c.StreamConfig
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if err := daemon.StartLogging(c); err != nil {
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c.Reset(false)
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return err
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}
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}
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if stdin := s.Stdin(); stdin != nil {
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if iop.Stdin != nil {
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go func() {
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io.Copy(iop.Stdin, stdin)
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iop.Stdin.Close()
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}()
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}
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} else {
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if c != nil && !c.Config.Tty {
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// tty is enabled, so dont close containerd's iopipe stdin.
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if iop.Stdin != nil {
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iop.Stdin.Close()
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}
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}
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}
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copyFunc := func(w io.Writer, r io.Reader) {
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s.Add(1)
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go func() {
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if _, err := io.Copy(w, r); err != nil {
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logrus.Errorf("%v stream copy error: %v", id, err)
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}
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s.Done()
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}()
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}
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if iop.Stdout != nil {
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copyFunc(s.Stdout(), iop.Stdout)
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}
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if iop.Stderr != nil {
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copyFunc(s.Stderr(), iop.Stderr)
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}
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return nil
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}
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