Automatic docker volume backup with git

This repository is the source of the fvanderbiest/volume-git-backup image on Docker Hub. The image provides an easy way to git commit a docker volume every time a file is updated. Feel free to use it if it suits your needs. Contributions welcomed.

This image expects to find the volume mounted in rw mode on /var/local/data.

The file to watch for changes should also be contained in this directory. Internally, we're using inotifywait to watch the file.

When change is detected, the script performs the commit and optionally pushes to a remote repository.

At startup, if a remote repository is configured a clone of this repository is done in the volume. If volume is not empty, you will need to set FORCE_CLONE var to 'yes' to force a cleanup of the volume. If the volume is already verionned (contains a .git folder) then git remote is updated and local repository is updated to the last commit of configured branch.

Example usage:

sync:
  image: fvanderbiest/volume-git-backup
  environment:
    WATCH_FILE: global.xml
    GIT_COMMIT_MESSAGE: printf "updateSequence "; grep updateSequence global.xml|sed -e 's#.*ce>\(.*\)</up.*#\1#'
    GIT_USERNAME: fvanderbiest
    GIT_EMAIL: my.email@provider.com
  volumes:
    - geoserver_datadir:/var/local/data:rw

Required environment:

• WATCH_FILE: file to watch (path relative to volume root)
• GIT_COMMIT_MESSAGE: string or expression evaluated in the volume to provide a commit message
• GIT_USERNAME: git username for commit
• GIT_EMAIL: git email for commit

To push to a repository, these additional variables are required:

• REMOTE_NAME: name of the git remote, eg origin
• REMOTE_URL: git repository URL, eg https://github.com/fvanderbiest/playground.git

Optional environment:

• REMOTE_BRANCH: Remote branch to use. Defaults to master.
• FORCE_CLONE: Delete volume content before cloning remote repository

To use SSH authentication to access remote repository, one of following variables must be set:

• GIT_RSA_DEPLOY_KEY: Private RSA key to use (eg: GitHub deploy keys)
• GIT_RSA_DEPLOY_KEY_FILE: Path to a file containing the private RSA key to use

WARNING: the git push command performs a forced update to the master branch, which might result in data loss !

Optional:

• SLEEPING_TIME: if WATCH_FILE does not exist at startup, time to wait before a new check starts. Defaults to 1 sec.

testing

In the tests folder there's a docker-compose file to easily create a testing environment.

The Dockerfile in the tests/geoserver_mock directory creates an image whose purpose is to periodically update the contents of a docker volume. It kind of mimics what GeoServer does to its config directory and is a lightweight alternative.