🏗️ How to develop on borgmatic

To get set up to develop on borgmatic, first install uv to make managing your borgmatic environment easier without impacting other Python applications on your system.

Then, clone borgmatic via HTTPS or SSH:

git clone https://projects.torsion.org/borgmatic-collective/borgmatic.git

Or:

git clone ssh://git@projects.torsion.org:3022/borgmatic-collective/borgmatic.git

Finally, install borgmatic "editable" so that you can run borgmatic actions during development to make sure your changes work:

cd borgmatic
uv tool update-shell
uv tool install --editable .

Or to work on the Apprise hook, change that last line to:

uv tool install --editable .[Apprise]

To get oriented with the borgmatic source code, have a look at the source code reference.

Source packages

Each borgmatic release also has source packages available. These include automated tests and serve as a good starting point for creating third-party borgmatic packages.

Automated tests

Assuming you've cloned the borgmatic source code as described above and you're in the borgmatic/ working copy, install tox and tox-uv using uv, which are used for setting up testing environments:

uv tool install tox --with tox-uv

Also install Ruff, which borgmatic uses for code linting and formatting:

uv tool install ruff

Finally, to actually run tests, run tox from inside the borgmatic source directory:

tox

That runs tests against all supported versions of Python, which takes a while. So if you'd only like to run tests against a single version of Python, e.g. Python 3.13:

tox -e py313

Code style

If when running tests, you get an error from Ruff's linter about files that don't meet linting requirements, you can ask Ruff to attempt to fix them for you via the following:

tox -e lint-fix

And if you get an error from the Ruff's code formatter about files that would be reformatted, you can ask Ruff to format them for you:

tox -e format

Similarly, if you get errors about spelling mistakes in source code, you can ask codespell to correct them:

tox -e spell

See the code style documentation for more specifics about borgmatic's own code style.

End-to-end tests

borgmatic additionally includes some end-to-end tests that integration test with Borg and supported databases for a few representative scenarios. These tests don't run by default when running tox, because they're relatively slow and depend on containers for runtime dependencies. These tests do run on the continuous integration (CI) server, and running them on your developer machine is the closest thing to dev-CI parity.

If you would like to run the end-to-end tests, first install Docker (or Podman; see below) and Docker Compose. Then run:

scripts/run-end-to-end-tests

This script assumes you have permission to run docker. If you don't, then you may need to run with sudo.

Podman

borgmatic's end-to-end tests optionally support using rootless Podman instead of Docker.

Setting up Podman is outside the scope of this documentation, but here are some key points to double-check:

• Install Podman and your desired networking support.
• Configure /etc/subuid and /etc/subgid to map users/groups for the non-root user who will run tests.
• Create a non-root Podman socket for that user:

  systemctl --user enable --now podman.socket
  systemctl --user start --now podman.socket

Then you'll be able to run end-to-end tests as per normal, and the test script will automatically use your non-root Podman socket instead of a Docker socket.

Continuous integration

Each commit to main triggers a continuous integration build which runs the test suite and updates documentation. These builds are also linked from the commits for the main branch.

Documentation development

Updates to borgmatic's documentation are welcome. It's formatted in Markdown and located in the docs/ directory in borgmatic's source, plus the README.md file at the root.

To build and view a copy of the documentation with your local changes, run the following from the root of borgmatic's source code:

scripts/dev-docs

This requires Docker (or Podman; see below) to be installed on your system. This script assumes you have permission to run docker. If you don't, then you may need to run with sudo.

How to choose a different port

You can choose a different listening port in two ways:

1. Modify the .env file

1. Open docs/.env.
2. Change PORT=8080 to your desired port number (e.g., PORT=3000).
3. Run the development script: scripts/dev-docs.

2. Use an environment variable

Alternatively, you can override the port directly from your terminal without modifying any files:

PORT=3000 ./scripts/dev-docs

After you run the script, you can point your web browser at http://localhost:8080/borgmatic/ (or your chosen port) to view the documentation with your changes.

To close the documentation server, ctrl-C the script. Note that it does not currently auto-reload, so you'll need to stop it and re-run it for any additional documentation changes to take effect.

Podman

borgmatic's developer build for documentation optionally supports using rootless Podman instead of Docker.

Setting up Podman is outside the scope of this documentation. But once you install and configure Podman, then scripts/dev-docs automatically uses Podman instead of Docker and Podman Compose (if present) instead of Docker Compose. However Podman works fine with either Podman Compose or Docker Compose.

Use of generative AI

Please do not use AI agents to modify this codebase. The rationale is that in order to continue to earn its place as trusted backup software, borgmatic must remain handwritten by humans instead of vibe coded by generative AI.

Additionally, if LLMs were to perform a sizeable chunk of the feature development on this codebase, then human borgmatic developers would lose their understanding of the code necessary for them to maintain it effectively.

Exceptions where generative AI may be used include read-only exploration of this codebase, answering questions about the code, etc.