borgmatic/docs/how-to/develop-on-borgmatic.md

---

title: How to develop on borgmatic eleventyNavigation: key: 🏗️ Develop on borgmatic parent: How-to guides

order: 15

Source code

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.

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

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.

Code style

When writing code for borgmatic, start with PEP 8. But then, apply the following deviations from it:

• For strings, prefer single quotes over double quotes.
• Limit all lines to a maximum of 100 characters.
• Use trailing commas within multiline values or argument lists.
• For multiline constructs, put opening and closing delimiters on lines separate from their contents.
• Within multiline constructs, use standard four-space indentation. Don't align indentation with an opening delimiter.
• In general, spell out words in variable names instead of shortening them. So, think index instead of idx. There are some notable exceptions to this though (like config).
• Favor blank lines around logical code groupings, if statements, returns, etc. Readability is more important than packing code tightly.
• Import fully qualified Python modules instead of importing individual functions, classes, or constants. E.g., do import os.path instead of from os import path. (Some exceptions to this are made in tests.)
• Only use classes and OOP as a last resort, such as when integrating with Python libraries that require it.
• Prefer functional code where it makes sense, e.g. when constructing a command (to subsequently execute imperatively).

Since borgmatic uses Ruff for code lining and formatting, many other code style requirements are also enforced when running automated tests.

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.

After you run the script, you can point your web browser at http://localhost:8080 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 should automatically use Podman instead of Docker.