scripts/backup-podman-volumes.py

"""
backup-podman-volumes

This script exports volumes defined in the configuration to
S3 and to a local path.

Usage: python <path>/backup-podman-volumes.py <config-path>
"""

# /// script
# dependencies = [
#   "pydantic",
#   "boto3"
# ]
# ///

import subprocess
import json
import sys
import pathlib
import logging
import shutil

import pydantic
import boto3

logger = logging.getLogger(__file__)
logging.basicConfig(
    filename="/var/log/backup-volumes.log", encoding="utf-8", level=logging.INFO
)


class Config(pydantic.BaseModel):
    # List of volumes to back up.
    volumes: list[str]
    # Local directory to save a copy of the latest volume to.
    local_backup_path: str
    # Bucket name to push the backed up archive to.
    bucket_name: str


def export_volume(volume_name: str, destination: pathlib.Path) -> str:
    """
    Exports a Podman volume identified by <volume_name> as a file
    located at <destination>.
    """
    result = subprocess.run(
        f'podman volume export {volume_name} -o "{str(destination)}"',
        shell=True,
        check=True,
    )

    logger.info(f"Exported {volume_name} to {destination}.")


def push_to_s3(source: pathlib.Path, bucket: str):
    """
    Pushes the given file to S3.

    The file name is reused as the object name, and the file
    located at <source> is pushed to bucket <bucket> under that
    name.
    """
    s3 = boto3.client("s3")
    object_name = source.name
    s3.upload_file(str(source), bucket, object_name)

    logger.info(f"Pushed {source} to {bucket} as {object_name}")


if __name__ == "__main__":
    config_path = sys.argv[1]

    if not pathlib.Path(config_path).exists():
        logger.error("Did not find configuration file at %s.", config_path)
        raise RuntimeError(f"Did not find configuration at {config_path}")

    config = Config.parse_file(config_path)

    for volume in config.volumes:
        exported_fn = f"{volume}.tar"
        exported_path = pathlib.Path("/tmp", exported_fn)

        export_volume(volume, exported_path)
        local_backup_path = pathlib.Path(config.local_backup_path, exported_fn)
        push_to_s3(exported_path, config.bucket_name)
        shutil.copy(exported_path, local_backup_path)

        logger.info(f"Backed up {volume} to S3 and local.")