container: T4870: remove manual user interaction during storage migration

Commit 60c80df4 ("container: T4870: bump package version 0 -> 1 for filesystem
change") introduced a fundamental change in the container storage driver that
required a manual migration step from the user to not loose any data.

This commit removes the manual user interaction and temporary exports the
container images and re-imports them after the filesystem got changed. The only
things that get lost are orphaned container images no longer referenced by the
CLI - thats an adequate trade-off as those images can always be re-added to the
system.

1 files changed, 45 insertions, 2 deletions

diff --git a/src/migration-scripts/container/0-to-1 b/src/migration-scripts/container/0-to-1
index 96ed6edee..d0461389b 100755
--- a/src/migration-scripts/container/0-to-1
+++ b/src/migration-scripts/container/0-to-1
@@ -17,18 +17,61 @@
 # T4870: change underlaying container filesystem from vfs to overlay
 
 import os
-import sys
 import shutil
+import sys
 
 from vyos.configtree import ConfigTree
+from vyos.util import call
 
 if (len(sys.argv) < 1):
     print("Must specify file name!")
     sys.exit(1)
 
-# We actually need no filename as this is a filesystem operation
+file_name = sys.argv[1]
+
+with open(file_name, 'r') as f:
+    config_file = f.read()
+
+base = ['container', 'name']
+config = ConfigTree(config_file)
+
+# Check if containers exist and we need to perform image manipulation
+if config.exists(base):
+    for container in config.list_nodes(base):
+        # Stop any given container first
+        call(f'systemctl stop vyos-container-{container}.service')
+        # Export container image for later re-import to new filesystem. We store
+        # the backup on a real disk as a tmpfs (like /tmp) could probably lack
+        # memory if a host has too many containers stored.
+        image_name = config.return_value(base + [container, 'image'])
+        call(f'podman image save --quiet --output /root/{container}.tar --format oci-archive {image_name}')
+
+# No need to adjust the strage driver online (this is only used for testing and
+# debugging on a live system) - it is already overlay2 when the migration script
+# is run during system update. But the specified driver in the image is actually
+# overwritten by the still present VFS filesystem on disk. Thus podman still
+# thinks it uses VFS until we delete the libpod directory under:
+# /usr/lib/live/mount/persistence/container/storage
+#call('sed -i "s/vfs/overlay2/g" /etc/containers/storage.conf /usr/share/vyos/templates/container/storage.conf.j2')
+
 base_path = '/usr/lib/live/mount/persistence/container/storage'
 for dir in ['libpod', 'vfs', 'vfs-containers', 'vfs-images', 'vfs-layers']:
     if os.path.exists(f'{base_path}/{dir}'):
         shutil.rmtree(f'{base_path}/{dir}')
 
+# Now all remaining information about VFS is gone and we operate in overlayfs2
+# filesystem mode. Time to re-import the images.
+if config.exists(base):
+    for container in config.list_nodes(base):
+        # Export container image for later re-import to new filesystem
+        image_name = config.return_value(base + [container, 'image'])
+        image_path = f'/root/{container}.tar'
+        call(f'podman image load --quiet --input {image_path}')
+
+        # Start any given container first
+        call(f'systemctl start vyos-container-{container}.service')
+
+        # Delete temporary container image
+        if os.path.exists(image_path):
+            os.unlink(image_path)
+