cmd/podman: add support for checkpoint images

This patch extends the podman run command with support for checkpoint
images. When `podman run` is invoked with an image that contains
a checkpoint, it would restore the container from that checkpoint.

Example:
    podman run -d --name looper busybox /bin/sh -c \
	    'i=0; while true; do echo $i; i=$(expr $i + 1); sleep 1; done'

    podman container checkpoint --create-image checkpoint-image-1 looper

    podman run checkpoint-image-1

Signed-off-by: Radostin Stoyanov <[email protected]>

cmd/podman/containers/restore.go

@@ -93,7 +93,7 @@ func init() {
 
 func restore(cmd *cobra.Command, args []string) error {
 	var (
-		e    error
+		err  error
 		errs utils.OutputErrors
 	)
 	podmanStart := time.Now()
@@ -104,9 +104,9 @@ func restore(cmd *cobra.Command, args []string) error {
 	// Check if the container exists (#15055)
 	exists := &entities.BoolReport{Value: false}
 	for _, ctr := range args {
-		exists, e = registry.ContainerEngine().ContainerExists(registry.GetContext(), ctr, entities.ContainerExistsOptions{})
-		if e != nil {
-			return e
+		exists, err = registry.ContainerEngine().ContainerExists(registry.GetContext(), ctr, entities.ContainerExistsOptions{})
+		if err != nil {
+			return err
 		}
 		if exists.Value {
 			break
@@ -115,9 +115,9 @@ func restore(cmd *cobra.Command, args []string) error {
 
 	if !exists.Value {
 		// Find out if this is an image
-		restoreOptions.CheckpointImage, e = utils.IsCheckpointImage(context.Background(), args)
-		if e != nil {
-			return e
+		restoreOptions.CheckpointImage, err = utils.IsCheckpointImage(context.Background(), args)
+		if err != nil {
+			return err
 		}
 	}
 

cmd/podman/containers/run.go

@@ -148,6 +148,35 @@ func run(cmd *cobra.Command, args []string) error {
 		imageName = name
 	}
 
+	// If this is a checkpoint image, invoke container restore.
+	// We do not return `err` when checkpointImage is false, because the value
+	// of `err` could be "image is not a checkpoint". In this case, the run
+	// command should continue as usual, preserving backwards compatibility.
+	checkpointImage, err := utils.IsCheckpointImage(registry.GetContext(), []string{imageName})
+	if checkpointImage {
+		if err != nil {
+			return err
+		}
+		var restoreOptions entities.RestoreOptions
+		responses, err := registry.ContainerEngine().ContainerRestore(registry.GetContext(), []string{imageName}, restoreOptions)
+		if err != nil {
+			return err
+		}
+
+		var errs utils.OutputErrors
+		for _, r := range responses {
+			switch {
+			case r.Err != nil:
+				errs = append(errs, r.Err)
+			case r.RawInput != "":
+				fmt.Println(r.RawInput)
+			default:
+				fmt.Println(r.Id)
+			}
+		}
+		return errs.PrintErrors()
+	}
+
 	if cliVals.Replace {
 		if err := replaceContainer(cliVals.Name); err != nil {
 			return err