containerd: Add a service command to cleanup stale containers on boot

This may occur if /var/lib/container happens to be on persistent storage.

Signed-off-by: Ian Campbell <ijc@docker.com>

pkg/containerd/Makefile

@@ -1,5 +1,5 @@
 IMAGE=containerd
 NETWORK=1
-DEPS=$(wildcard etc/init.d/*) etc/containerd/config.toml
+DEPS=$(wildcard etc/init.d/*) $(wildcard cmd/service/*.go) etc/containerd/config.toml
 
 include ../package.mk

pkg/containerd/cmd/service/main.go

@@ -29,6 +29,7 @@ func main() {
 	flag.Usage = func() {
 		fmt.Printf("USAGE: %s [options] COMMAND\n\n", filepath.Base(os.Args[0]))
 		fmt.Printf("Commands:\n")
+		fmt.Printf("  system-init Prepare the system at start of day\n")
 		fmt.Printf("  start       Start a service\n")
 		fmt.Printf("  help        Print this message\n")
 		fmt.Printf("\n")
@@ -67,6 +68,8 @@ func main() {
 	switch args[0] {
 	case "start":
 		start(args[1:])
+	case "system-init":
+		systemInit(args[1:])
 	default:
 		fmt.Printf("%q is not valid command.\n\n", args[0])
 		flag.Usage()

pkg/containerd/cmd/service/system_init.go

@@ -0,0 +1,101 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"os"
+	"path/filepath"
+	"syscall"
+
+	log "github.com/Sirupsen/logrus"
+	"github.com/containerd/containerd"
+	"github.com/containerd/containerd/namespaces"
+	"github.com/pkg/errors"
+)
+
+func cleanupTask(ctx context.Context, ctr containerd.Container) error {
+	task, err := ctr.Task(ctx, nil)
+	if err != nil {
+		if err == containerd.ErrNoRunningTask {
+			return nil
+		}
+		return errors.Wrap(err, "getting task")
+	}
+
+	deleteErr := make(chan error, 1)
+	deleteCtx, deleteCancel := context.WithCancel(ctx)
+	defer deleteCancel()
+
+	go func(ctx context.Context, ch chan error) {
+		_, err := task.Delete(ctx)
+		if err != nil {
+			ch <- errors.Wrap(err, "killing task")
+		}
+		ch <- nil
+	}(deleteCtx, deleteErr)
+
+	sig := syscall.SIGKILL
+	if err := task.Kill(ctx, sig); err != nil && err != containerd.ErrProcessExited {
+		return errors.Wrapf(err, "killing task with %q", sig)
+	}
+
+	select {
+	case err := <-deleteErr:
+		return err
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func systemInit(args []string) {
+	invoked := filepath.Base(os.Args[0])
+	flags := flag.NewFlagSet("system-init", flag.ExitOnError)
+	flags.Usage = func() {
+		fmt.Printf("USAGE: %s system-init\n\n", invoked)
+		fmt.Printf("Options:\n")
+		flags.PrintDefaults()
+	}
+
+	sock := flags.String("sock", "/run/containerd/containerd.sock", "Path to containerd socket")
+
+	if err := flags.Parse(args); err != nil {
+		log.Fatal("Unable to parse args")
+	}
+	args = flags.Args()
+
+	if len(args) != 0 {
+		fmt.Println("Unexpected argument")
+		flags.Usage()
+		os.Exit(1)
+	}
+
+	client, err := containerd.New(*sock)
+	if err != nil {
+		log.WithError(err).Fatal("creating containerd client")
+	}
+
+	ctx := namespaces.WithNamespace(context.Background(), "default")
+
+	ctrs, err := client.Containers(ctx)
+	if err != nil {
+		log.WithError(err).Fatal("listing containers")
+	}
+
+	// None of the errors in this loop are fatal since we want to
+	// keep trying.
+	for _, ctr := range ctrs {
+		log.Infof("Cleaning up stale service: %q", ctr.ID())
+		log := log.WithFields(log.Fields{
+			"service": ctr.ID(),
+		})
+
+		if err := cleanupTask(ctx, ctr); err != nil {
+			log.WithError(err).Error("cleaning up task")
+		}
+
+		if err := ctr.Delete(ctx); err != nil {
+			log.WithError(err).Error("deleting container")
+		}
+	}
+}

pkg/containerd/etc/init.d/020-containerd

@@ -12,6 +12,8 @@ done
 
 # start service containers
 
+service system-init
+
 if [ -d /containers/services ]
 then
 	for f in $(find /containers/services -mindepth 1 -maxdepth 1 | sort)