# Copyright 2022-2024 VyOS maintainers and contributors <maintainers@vyos.io>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
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# version 2.1 of the License, or (at your option) any later version.
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# Lesser General Public License for more details.
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# T4870: change underlaying container filesystem from vfs to overlay

import os
import shutil

from vyos.configtree import ConfigTree
from vyos.utils.process import call

base = ['container', 'name']

def migrate(config: ConfigTree) -> None:
    # 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'sudo 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'sudo 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'sudo podman image load --quiet --input {image_path}')

            # Start any given container first
            call(f'sudo systemctl start vyos-container-{container}.service')

            # Delete temporary container image
            if os.path.exists(image_path):
                os.unlink(image_path)