Ignore missing config.v2.json files on migration

pkg/storagemigration/failcleanup.go

@@ -10,7 +10,6 @@ import (
 // FailCleanup should be run after a failed migration.
 // It will remove any files left over from the migration process
 // and migrate containers back to aufs.
-//
 func failCleanup(root string) error {
 	logrus.WithField("storage_root", root).Warning("recovering from failed aufs to overlay migration")
 

pkg/storagemigration/migrate.go

@@ -128,7 +128,6 @@ func Migrate(root string) (err error) {
 	if err != nil {
 		return fmt.Errorf("Error migrating containers to overlay2: %v", err)
 	}
-
 	return nil
 }
 
@@ -336,10 +335,17 @@ func SwitchAllContainersStorageDriver(root, newStorageDriver string) error {
 	logrus.Debugf("migrating %v container(s) to %s", len(containerIDs), newStorageDriver)
 	for _, containerID := range containerIDs {
 		err := switchContainerStorageDriver(root, containerID, newStorageDriver)
-		if err != nil {
+		switch err {
+		case nil:
+			logrus.WithField("container_id", containerID).Debugf("reconfigured storage-driver to %s", newStorageDriver)
+		case errNoConfigV2JSON:
+			if newStorageDriver == "overlay2" {
+				return fmt.Errorf("Error containerID %s: %v", containerID, err)
+			}
+			logrus.WithField("container_id", containerID).Errorf("has no config.v2.json %s", newStorageDriver)
+		default:
 			return fmt.Errorf("Error rewriting container config for %s: %v", containerID, err)
 		}
-		logrus.WithField("container_id", containerID).Debugf("reconfigured storage-driver to %s", newStorageDriver)
 	}
 	return nil
 }

pkg/storagemigration/migrate_test.go

@@ -41,6 +41,7 @@ func setup(t *testing.T) (*fs.Dir, *State, func()) {
 			),
 		),
 	)
+
 	state := &State{
 		Layers: []Layer{
 			{
@@ -132,3 +133,37 @@ func TestFailCleanup(t *testing.T) {
 	_, err = os.Stat(root.Join("aufs"))
 	assert.NilError(t, err)
 }
+
+func TestFailCleanupContainer(t *testing.T) {
+	root, _, cleanup := setup(t)
+	defer cleanup()
+
+	// delete config.v2.json to force SwitchAllContainersStorageDriver to fail
+	os.Remove(root.Join("containers", "bebe92422caf828ab21ae39974a0c003a29970ec09c6e5529bbb24f71eb9ca2ef", "config.v2.json"))
+
+	err := Migrate(root.Path())
+	if err == nil {
+		// won't err on rollback to aufs fail
+		assert.NilError(t, err)
+	} else {
+		// only errs on migration to overlay2 fail
+		assert.ErrorContains(t, err, "bebe92422caf828ab21ae39974a0c003a29970ec09c6e5529bbb24f71eb9ca2ef")
+
+		// // config.v2.json should not exists
+		_, err = os.Stat(root.Join("containers", "bebe92422caf828ab21ae39974a0c003a29970ec09c6e5529bbb24f71eb9ca2ef", "config.v2.json"))
+		assert.ErrorType(t, err, os.IsNotExist)
+
+		// migration logfile should exists
+		_, err = os.Stat(root.Join("migrate.log"))
+		assert.NilError(t, err)
+
+		// overlay2 directory should not exists
+		_, err = os.Stat(root.Join("overlay2"))
+		println("err", root.Join("overlay2"), err)
+		assert.ErrorType(t, err, os.IsNotExist)
+
+		// aufs directory should still exists
+		_, err = os.Stat(root.Join("aufs"))
+		assert.NilError(t, err)
+	}
+}

pkg/storagemigration/utils.go

@@ -2,6 +2,7 @@ package storagemigration
 
 import (
 	"encoding/json"
+	"errors"
 	"os"
 	"path/filepath"
 
@@ -11,6 +12,8 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+var errNoConfigV2JSON = errors.New("config.v2.json not found for container")
+
 // exists checks if a file  (or if isDir is set to "true" a directory) exists
 func exists(path string, isDir bool) (bool, error) {
 	fi, err := os.Stat(path)
@@ -60,6 +63,10 @@ func replicate(sourceDir, targetDir string) error {
 // this is the only change needed to make it work after the migration
 func switchContainerStorageDriver(root, containerID, newStorageDriver string) error {
 	containerConfigPath := filepath.Join(root, "containers", containerID, "config.v2.json")
+	if ok, _ := exists(containerConfigPath, false); !ok {
+		return errNoConfigV2JSON
+	}
+
 	f, err := os.OpenFile(containerConfigPath, os.O_RDWR, os.ModePerm)
 	if err != nil {
 		return err