Add restart policy for containers

cmd/podman/common.go

@@ -444,7 +444,7 @@ func getCreateFlags(c *cliconfig.PodmanCommand) {
 	)
 	createFlags.String(
 		"restart", "",
-		"Restart is not supported.  Please use a systemd unit file for restart",
+		"Restart policy to apply when a container exits",
 	)
 	createFlags.Bool(
 		"rm", false,

cmd/podman/shared/create.go

@@ -41,6 +41,9 @@ func CreateContainer(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		span, _ := opentracing.StartSpanFromContext(ctx, "createContainer")
 		defer span.Finish()
 	}
+	if c.Bool("rm") && c.String("restart") != "" && c.String("restart") != "no" {
+		return nil, nil, errors.Errorf("the --rm option conflicts with --restart")
+	}
 
 	rtc, err := runtime.GetConfig()
 	if err != nil {
@@ -279,9 +282,6 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		blkioWeight                                              uint16
 		namespaces                                               map[string]string
 	)
-	if c.IsSet("restart") {
-		return nil, errors.Errorf("--restart option is not supported.\nUse systemd unit files for restarting containers")
-	}
 
 	idmappings, err := util.ParseIDMapping(c.StringSlice("uidmap"), c.StringSlice("gidmap"), c.String("subuidname"), c.String("subgidname"))
 	if err != nil {
@@ -676,21 +676,22 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 			PidsLimit:         c.Int64("pids-limit"),
 			Ulimit:            c.StringSlice("ulimit"),
 		},
-		Rm:          c.Bool("rm"),
-		StopSignal:  stopSignal,
-		StopTimeout: c.Uint("stop-timeout"),
-		Sysctl:      sysctl,
-		Systemd:     systemd,
-		Tmpfs:       c.StringSlice("tmpfs"),
-		Tty:         tty,
-		User:        user,
-		UsernsMode:  usernsMode,
-		MountsFlag:  c.StringArray("mount"),
-		Volumes:     c.StringArray("volume"),
-		WorkDir:     workDir,
-		Rootfs:      rootfs,
-		VolumesFrom: c.StringSlice("volumes-from"),
-		Syslog:      c.Bool("syslog"),
+		RestartPolicy: c.String("restart"),
+		Rm:            c.Bool("rm"),
+		StopSignal:    stopSignal,
+		StopTimeout:   c.Uint("stop-timeout"),
+		Sysctl:        sysctl,
+		Systemd:       systemd,
+		Tmpfs:         c.StringSlice("tmpfs"),
+		Tty:           tty,
+		User:          user,
+		UsernsMode:    usernsMode,
+		MountsFlag:    c.StringArray("mount"),
+		Volumes:       c.StringArray("volume"),
+		WorkDir:       workDir,
+		Rootfs:        rootfs,
+		VolumesFrom:   c.StringSlice("volumes-from"),
+		Syslog:        c.Bool("syslog"),
 	}
 
 	if config.Privileged {

docs/podman-create.1.md

@@ -567,11 +567,17 @@ If container is running in --read-only mode, then mount a read-write tmpfs on /r
 
 **--restart=""**
 
-Not implemented.
+Restart policy to follow when containers exit.
+Restart policy will not take effect if a container is stopped via the `podman kill` or `podman stop` commands.
+Valid values are:
 
-Restart should be handled via a systemd unit files. Please add your podman
-commands to a unit file and allow systemd or your init system to handle the
-restarting of the container processes.  See example below.
+- `no`                       : Do not restart containers on exit
+- `on-failure[:max_retries]` : Restart containers when they exit with a non-0 exit code, retrying indefinitely or until the optional max_retries count is hit
+- `always`                   : Restart containers when they exit, regardless of status, retrying indefinitely
+
+Please note that restart will not restart containers after a system reboot.
+If this functionality is required in your environment, you can invoke Podman from a systemd unit file, or create an init script for whichever init system is in use.
+To generate systemd unit files, please see *podman generate systemd*
 
 **--rm**=*true*|*false*
 
@@ -859,21 +865,6 @@ the uids and gids from the host.
 $ podman create --uidmap 0:30000:7000 --gidmap 0:30000:7000 fedora echo hello
 ```
 
-### Running a podman container to restart inside of a systemd unit file
-
-
-```
-[Unit]
-Description=My App
-[Service]
-Restart=always
-ExecStart=/usr/bin/podman start -a my_app
-ExecStop=/usr/bin/podman stop -t 10 my_app
-KillMode=process
-[Install]
-WantedBy=multi-user.target
-```
-
 ### Rootless Containers
 
 Podman runs as a non root user on most systems. This feature requires that a new enough version of shadow-utils

docs/podman-events.1.md

@@ -28,6 +28,7 @@ The *container* event type will report the follow statuses:
  * pause
  * prune
  * remove
+ * restart
  * restore
  * start
  * stop

docs/podman-run.1.md

@@ -589,11 +589,17 @@ If container is running in --read-only mode, then mount a read-write tmpfs on /r
 
 **--restart=""**
 
-Not implemented.
+Restart policy to follow when containers exit.
+Restart policy will not take effect if a container is stopped via the `podman kill` or `podman stop` commands.
+Valid values are:
 
-Restart should be handled via a systemd unit files. Please add your podman
-commands to a unit file and allow systemd or your init system to handle the
-restarting of the container processes. See *podman generate systemd*.
+- `no`                       : Do not restart containers on exit
+- `on-failure[:max_retries]` : Restart containers when they exit with a non-0 exit code, retrying indefinitely or until the optional max_retries count is hit
+- `always`                   : Restart containers when they exit, regardless of status, retrying indefinitely
+
+Please note that restart will not restart containers after a system reboot.
+If this functionality is required in your environment, you can invoke Podman from a systemd unit file, or create an init script for whichever init system is in use.
+To generate systemd unit files, please see *podman generate systemd*
 
 **--rm**=*true*|*false*
 

libpod/container.go

@@ -102,6 +102,20 @@ func (ns LinuxNS) String() string {
 	}
 }
 
+// Valid restart policy types.
+const (
+	// RestartPolicyNone indicates that no restart policy has been requested
+	// by a container.
+	RestartPolicyNone = ""
+	// RestartPolicyNo is identical in function to RestartPolicyNone.
+	RestartPolicyNo = "no"
+	// RestartPolicyAlways unconditionally restarts the container.
+	RestartPolicyAlways = "always"
+	// RestartPolicyOnFailure restarts the container on non-0 exit code,
+	// with an optional maximum number of retries.
+	RestartPolicyOnFailure = "on-failure"
+)
+
 // Container is a single OCI container.
 // All operations on a Container that access state must begin with a call to
 // syncContainer().
@@ -179,6 +193,16 @@ type ContainerState struct {
 	// This maps the path the file will be mounted to in the container to
 	// the path of the file on disk outside the container
 	BindMounts map[string]string `json:"bindMounts,omitempty"`
+	// StoppedByUser indicates whether the container was stopped by an
+	// explicit call to the Stop() API.
+	StoppedByUser bool `json:"stoppedByUser,omitempty"`
+	// RestartPolicyMatch indicates whether the conditions for restart
+	// policy have been met.
+	RestartPolicyMatch bool `json:"restartPolicyMatch,omitempty"`
+	// RestartCount is how many times the container was restarted by its
+	// restart policy. This is NOT incremented by normal container restarts
+	// (only by restart policy).
+	RestartCount uint `json:"restartCount,omitempty"`
 
 	// ExtensionStageHooks holds hooks which will be executed by libpod
 	// and not delegated to the OCI runtime.
@@ -346,6 +370,17 @@ type ContainerConfig struct {
 	LogPath string `json:"logPath"`
 	// File containing the conmon PID
 	ConmonPidFile string `json:"conmonPidFile,omitempty"`
+	// RestartPolicy indicates what action the container will take upon
+	// exiting naturally.
+	// Allowed options are "no" (take no action), "on-failure" (restart on
+	// non-zero exit code, up an a maximum of RestartRetries times),
+	// and "always" (always restart the container on any exit code).
+	// The empty string is treated as the default ("no")
+	RestartPolicy string `json:"restart_policy,omitempty"`
+	// RestartRetries indicates the number of attempts that will be made to
+	// restart the container. Used only if RestartPolicy is set to
+	// "on-failure".
+	RestartRetries uint `json:"restart_retries,omitempty"`
 	// TODO log options for log drivers
 
 	PostConfigureNetNS bool `json:"postConfigureNetNS"`
@@ -729,6 +764,17 @@ func (c *Container) LogPath() string {
 	return c.config.LogPath
 }
 
+// RestartPolicy returns the container's restart policy.
+func (c *Container) RestartPolicy() string {
+	return c.config.RestartPolicy
+}
+
+// RestartRetries returns the number of retries that will be attempted when
+// using the "on-failure" restart policy
+func (c *Container) RestartRetries() uint {
+	return c.config.RestartRetries
+}
+
 // RuntimeName returns the name of the runtime
 func (c *Container) RuntimeName() string {
 	return c.runtime.ociRuntime.name
@@ -1003,6 +1049,21 @@ func (c *Container) BindMounts() (map[string]string, error) {
 	return newMap, nil
 }
 
+// StoppedByUser returns whether the container was last stopped by an explicit
+// call to the Stop() API, or whether it exited naturally.
+func (c *Container) StoppedByUser() (bool, error) {
+	if !c.batched {
+		c.lock.Lock()
+		defer c.lock.Unlock()
+
+		if err := c.syncContainer(); err != nil {
+			return false, err
+		}
+	}
+
+	return c.state.StoppedByUser, nil
+}
+
 // Misc Accessors
 // Most will require locking
 

libpod/container_api.go

@@ -57,11 +57,11 @@ func (c *Container) Init(ctx context.Context) (err error) {
 
 	if c.state.State == ContainerStateStopped {
 		// Reinitialize the container
-		return c.reinit(ctx)
+		return c.reinit(ctx, false)
 	}
 
 	// Initialize the container for the first time
-	return c.init(ctx)
+	return c.init(ctx, false)
 }
 
 // Start starts a container.
@@ -199,8 +199,15 @@ func (c *Container) Kill(signal uint) error {
 	if c.state.State != ContainerStateRunning {
 		return errors.Wrapf(ErrCtrStateInvalid, "can only kill running containers")
 	}
+
 	defer c.newContainerEvent(events.Kill)
-	return c.runtime.ociRuntime.killContainer(c, signal)
+	if err := c.runtime.ociRuntime.killContainer(c, signal); err != nil {
+		return err
+	}
+
+	c.state.StoppedByUser = true
+
+	return c.save()
 }
 
 // Exec starts a new process inside the container
@@ -583,6 +590,7 @@ func (c *Container) Cleanup(ctx context.Context) error {
 	if !c.batched {
 		c.lock.Lock()
 		defer c.lock.Unlock()
+
 		if err := c.syncContainer(); err != nil {
 			return err
 		}
@@ -593,6 +601,19 @@ func (c *Container) Cleanup(ctx context.Context) error {
 		return errors.Wrapf(ErrCtrStateInvalid, "container %s is running or paused, refusing to clean up", c.ID())
 	}
 
+	// Handle restart policy.
+	// Returns a bool indicating whether we actually restarted.
+	// If we did, don't proceed to cleanup - just exit.
+	didRestart, err := c.handleRestartPolicy(ctx)
+	if err != nil {
+		return err
+	}
+	if didRestart {
+		return nil
+	}
+
+	// If we didn't restart, we perform a normal cleanup
+
 	// Check if we have active exec sessions
 	if len(c.state.ExecSessions) != 0 {
 		return errors.Wrapf(ErrCtrStateInvalid, "container %s has active exec sessions, refusing to clean up", c.ID())
@@ -754,7 +775,7 @@ func (c *Container) Refresh(ctx context.Context) error {
 		if err := c.prepare(); err != nil {
 			return err
 		}
-		if err := c.init(ctx); err != nil {
+		if err := c.init(ctx, false); err != nil {
 			return err
 		}
 	}

libpod/container_inspect.go

@@ -95,6 +95,7 @@ func (c *Container) getContainerInspectData(size bool, driverData *inspect.Data)
 		LogPath:         config.LogPath,
 		ConmonPidFile:   config.ConmonPidFile,
 		Name:            config.Name,
+		RestartCount:    int32(runtimeInfo.RestartCount),
 		Driver:          driverData.Name,
 		MountLabel:      config.MountLabel,
 		ProcessLabel:    config.ProcessLabel,