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, 9 insertions, 1 deletions

diff --git a/pkg/adapter/containers_remote.go b/pkg/adapter/containers_remote.go
index bc6a9cfcd..776fcbb70 100644
--- a/pkg/adapter/containers_remote.go
+++ b/pkg/adapter/containers_remote.go
@@ -664,6 +664,10 @@ func (r *LocalRuntime) Attach(ctx context.Context, c *cliconfig.AttachValues) er
 
 // Checkpoint one or more containers
 func (r *LocalRuntime) Checkpoint(c *cliconfig.CheckpointValues, options libpod.ContainerCheckpointOptions) error {
+	if c.Export != "" {
+		return errors.New("the remote client does not support exporting checkpoints")
+	}
+
 	var lastError error
 	ids, err := iopodman.GetContainersByContext().Call(r.Conn, c.All, c.Latest, c.InputArgs)
 	if err != nil {
@@ -699,7 +703,11 @@ 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 {
+	if c.Import != "" {
+		return errors.New("the remote client does not support importing checkpoints")
+	}
+
 	var lastError error
 	ids, err := iopodman.GetContainersByContext().Call(r.Conn, c.All, c.Latest, c.InputArgs)
 	if err != nil {