system: add new subcommand "migrate"

it is useful to migrate existing containers to a new version of
podman.  Currently, it is needed to migrate rootless containers that
were created with podman <= 1.2 to a newer version which requires all
containers to be running in the same user namespace.

Closes: https://github.com/containers/libpod/issues/2935

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/cmd/podman/libpodruntime/runtime.go b/cmd/podman/libpodruntime/runtime.go
index 78adf1252..595f8267f 100644
--- a/cmd/podman/libpodruntime/runtime.go
+++ b/cmd/podman/libpodruntime/runtime.go
@@ -9,17 +9,22 @@ import (
 	"github.com/pkg/errors"
 )
 
+// GetRuntimeMigrate gets a libpod runtime that will perform a migration of existing containers
+func GetRuntimeMigrate(c *cliconfig.PodmanCommand) (*libpod.Runtime, error) {
+	return getRuntime(c, false, true)
+}
+
 // GetRuntimeRenumber gets a libpod runtime that will perform a lock renumber
 func GetRuntimeRenumber(c *cliconfig.PodmanCommand) (*libpod.Runtime, error) {
-	return getRuntime(c, true)
+	return getRuntime(c, true, false)
 }
 
 // GetRuntime generates a new libpod runtime configured by command line options
 func GetRuntime(c *cliconfig.PodmanCommand) (*libpod.Runtime, error) {
-	return getRuntime(c, false)
+	return getRuntime(c, false, false)
 }
 
-func getRuntime(c *cliconfig.PodmanCommand, renumber bool) (*libpod.Runtime, error) {
+func getRuntime(c *cliconfig.PodmanCommand, renumber bool, migrate bool) (*libpod.Runtime, error) {
 	options := []libpod.RuntimeOption{}
 	storageOpts := storage.StoreOptions{}
 	storageSet := false
@@ -63,6 +68,9 @@ func getRuntime(c *cliconfig.PodmanCommand, renumber bool) (*libpod.Runtime, err
 		storageSet = true
 		storageOpts.GraphDriverOptions = c.GlobalFlags.StorageOpts
 	}
+	if migrate {
+		options = append(options, libpod.WithMigrate())
+	}
 
 	if renumber {
 		options = append(options, libpod.WithRenumber())