system: migrate stops the pause process

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

cmd/podman/main_local.go

@@ -132,6 +132,7 @@ func setupRootless(cmd *cobra.Command, args []string) error {
 		became, ret, err := rootless.JoinUserAndMountNS(uint(pausePid), "")
 		if err != nil {
 			logrus.Errorf("cannot join pause process pid %d.  You may need to remove %s and stop all containers", pausePid, pausePidPath)
+			logrus.Errorf("you can use `system migrate` to recreate the pause process")
 			logrus.Errorf(err.Error())
 			os.Exit(1)
 		}

libpod/runtime_migrate.go

@@ -1,14 +1,47 @@
+// +build linux
+
 package libpod
 
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
+	"os"
 	"path/filepath"
+	"strconv"
+	"syscall"
 
+	"github.com/containers/libpod/pkg/rootless"
+	"github.com/containers/libpod/pkg/util"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 )
 
+func stopPauseProcess() error {
+	if rootless.IsRootless() {
+		pausePidPath, err := util.GetRootlessPauseProcessPidPath()
+		if err != nil {
+			return errors.Wrapf(err, "could not get pause process pid file path")
+		}
+		data, err := ioutil.ReadFile(pausePidPath)
+		if err != nil {
+			if os.IsNotExist(err) {
+				return nil
+			}
+			return errors.Wrapf(err, "cannot read pause process pid file %s", pausePidPath)
+		}
+		pausePid, err := strconv.Atoi(string(data))
+		if err != nil {
+			return errors.Wrapf(err, "cannot parse pause pid file %s", pausePidPath)
+		}
+		if err := os.Remove(pausePidPath); err != nil {
+			return errors.Wrapf(err, "cannot delete pause pid file %s", pausePidPath)
+		}
+		syscall.Kill(pausePid, syscall.SIGKILL)
+	}
+	return nil
+}
+
 func (r *Runtime) migrate(ctx context.Context) error {
 	runningContainers, err := r.GetRunningContainers()
 	if err != nil {
@@ -39,5 +72,5 @@ func (r *Runtime) migrate(ctx context.Context) error {
 		}
 	}
 
-	return nil
+	return stopPauseProcess()
 }

libpod/runtime_migrate_unsupported.go

@@ -0,0 +1,11 @@
+// +build !linux
+
+package libpod
+
+import (
+	"context"
+)
+
+func (r *Runtime) migrate(ctx context.Context) error {
+	return nil
+}