migration: add possibility to restore a container with a new name

The option to restore a container from an external checkpoint archive
(podman container restore -i /tmp/checkpoint.tar.gz) restores a
container with the same name and same ID as id had before checkpointing.

This commit adds the option '--name,-n' to 'podman container restore'.
With this option the restored container gets the name specified after
'--name,-n' and a new ID. This way it is possible to restore one
container multiple times.

If a container is restored with a new name Podman will not try to
request the same IP address for the container as it had during
checkpointing. This implicitly assumes that if a container is restored
from a checkpoint archive with a different name, that it will be
restored multiple times and restoring a container multiple times with
the same IP address will fail as each IP address can only be used once.

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

2 files changed, 32 insertions, 2 deletions

diff --git a/pkg/adapter/checkpoint_restore.go b/pkg/adapter/checkpoint_restore.go
index 4ca17dd93..97ba5ecf7 100644
--- a/pkg/adapter/checkpoint_restore.go
+++ b/pkg/adapter/checkpoint_restore.go
@@ -41,7 +41,7 @@ func crImportFromJSON(filePath string, v interface{}) error {
 
 // crImportCheckpoint it the function which imports the information
 // from checkpoint tarball and re-creates the container from that information
-func crImportCheckpoint(ctx context.Context, runtime *libpod.Runtime, input string) ([]*libpod.Container, error) {
+func crImportCheckpoint(ctx context.Context, runtime *libpod.Runtime, input string, name string) ([]*libpod.Container, error) {
 	// First get the container definition from the
 	// tarball to a temporary directory
 	archiveFile, err := os.Open(input)
@@ -85,6 +85,18 @@ func crImportCheckpoint(ctx context.Context, runtime *libpod.Runtime, input stri
 		return nil, errors.Errorf("Cannot import checkpoints of containers with named volumes or dependencies")
 	}
 
+	ctrID := config.ID
+	newName := false
+
+	// Check if the restored container gets a new name
+	if name != "" {
+		config.ID = ""
+		config.Name = name
+		newName = true
+	}
+
+	ctrName := config.Name
+
 	// The code to load the images is copied from create.go
 	var writer io.Writer
 	// In create.go this only set if '--quiet' does not exist.
@@ -110,6 +122,24 @@ func crImportCheckpoint(ctx context.Context, runtime *libpod.Runtime, input stri
 		return nil, nil
 	}
 
+	containerConfig := container.Config()
+	if containerConfig.Name != ctrName {
+		return nil, errors.Errorf("Name of restored container (%s) does not match requested name (%s)", containerConfig.Name, ctrName)
+	}
+
+	if newName == false {
+		// Only check ID for a restore with the same name.
+		// Using -n to request a new name for the restored container, will also create a new ID
+		if containerConfig.ID != ctrID {
+			return nil, errors.Errorf("ID of restored container (%s) does not match requested ID (%s)", containerConfig.ID, ctrID)
+		}
+	}
+
+	// Check if the ExitCommand points to the correct container ID
+	if containerConfig.ExitCommand[len(containerConfig.ExitCommand)-1] != containerConfig.ID {
+		return nil, errors.Errorf("'ExitCommandID' uses ID %s instead of container ID %s", containerConfig.ExitCommand[len(containerConfig.ExitCommand)-1], containerConfig.ID)
+	}
+
 	containers = append(containers, container)
 	return containers, nil
 }
diff --git a/pkg/adapter/containers.go b/pkg/adapter/containers.go
index b7f4c272b..29297fbd5 100644
--- a/pkg/adapter/containers.go
+++ b/pkg/adapter/containers.go
@@ -539,7 +539,7 @@ func (r *LocalRuntime) Restore(ctx context.Context, c *cliconfig.RestoreValues,
 	})
 
 	if c.Import != "" {
-		containers, err = crImportCheckpoint(ctx, r.Runtime, c.Import)
+		containers, err = crImportCheckpoint(ctx, r.Runtime, c.Import, c.Name)
 	} else if c.All {
 		containers, err = r.GetContainers(filterFuncs...)
 	} else {