Added support to migrate containers

This commit adds an option to the checkpoint command to export a
checkpoint into a tar.gz file as well as importing a checkpoint tar.gz
file during restore. With all checkpoint artifacts in one file it is
possible to easily transfer a checkpoint and thus enabling container
migration in Podman. With the following steps it is possible to migrate
a running container from one system (source) to another (destination).

 Source system:
  * podman container checkpoint -l -e /tmp/checkpoint.tar.gz
  * scp /tmp/checkpoint.tar.gz destination:/tmp

 Destination system:
  * podman pull 'container-image-as-on-source-system'
  * podman container restore -i /tmp/checkpoint.tar.gz

The exported tar.gz file contains the checkpoint image as created by
CRIU and a few additional JSON files describing the state of the
checkpointed container.

Now the container is running on the destination system with the same
state just as during checkpointing. If the container is kept running
on the source system with the checkpoint flag '-R', the result will be
that the same container is running on two different hosts.

Signed-off-by: Adrian Reber <areber@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/pkg/adapter/containers.go b/pkg/adapter/containers.go
index 34ee70d3d..b7f4c272b 100644
--- a/pkg/adapter/containers.go
+++ b/pkg/adapter/containers.go
@@ -526,7 +526,7 @@ func (r *LocalRuntime) Checkpoint(c *cliconfig.CheckpointValues, options libpod.
 }
 
 // Restore one or more containers
-func (r *LocalRuntime) Restore(c *cliconfig.RestoreValues, options libpod.ContainerCheckpointOptions) error {
+func (r *LocalRuntime) Restore(ctx context.Context, c *cliconfig.RestoreValues, options libpod.ContainerCheckpointOptions) error {
 	var (
 		containers     []*libpod.Container
 		err, lastError error
@@ -538,7 +538,9 @@ func (r *LocalRuntime) Restore(c *cliconfig.RestoreValues, options libpod.Contai
 		return state == libpod.ContainerStateExited
 	})
 
-	if c.All {
+	if c.Import != "" {
+		containers, err = crImportCheckpoint(ctx, r.Runtime, c.Import)
+	} else if c.All {
 		containers, err = r.GetContainers(filterFuncs...)
 	} else {
 		containers, err = shortcuts.GetContainersByContext(false, c.Latest, c.InputArgs, r.Runtime)