Development guide

This page provides procedures and guidelines for developing and contributing to Gafaelfawr.

Scope of contributions

Gafaelfawr is an open source package, meaning that you can contribute to Gafaelfawr itself, or fork Gafaelfawr for your own purposes.

Since Gafaelfawr is intended for internal use by Rubin Observatory, community contributions can only be accepted if they align with Rubin Observatory’s aims. For that reason, it’s a good idea to propose changes with a new GitHub issue before investing time in making a pull request.

Gafaelfawr is developed by the LSST SQuaRE team.

Setting up a local development environment

Prerequisites

Gafaelfawr uses uv for all dependency management. A reasonably recent version of uv must already be installed. See the uv installation instructions if needed.

Gafaelfawr development requires Docker be installed locally. The user doing development must be able to start and manage Docker containers.

Set up development environment

To develop Gafaelfawr, create a virtual environment with uv venv and then run make init.

git clone https://github.com/lsst-sqre/gafaelfawr.git
cd gafaelfawr
uv venv
make init

This init step does three things:

  1. Installs Gafaelfawr in a virtualenv in the .venv directory, including the dependency groups for local development.

  2. Installs pre-commit, tox, and the necessary tox plugins.

  3. Installs the pre-commit hooks.

On macOS hosts, you may need to run the following before running make init and in the same terminal window.

export LDFLAGS="-L/usr/local/opt/openssl/lib"

Otherwise, OpenSSL isn’t on the default linker path and some Python extensions may not build. This must be set in any terminal window where you may run tox.

Finally, you can optionally enter the Gafaelfawr development virtualenv with:

source .venv/bin/activate

This is optional; you do not have to activate the virtualenv to do development. However, if you do, you can omit uv run from the start of all commands described below. Also, editors with Python integration, such as VSCode, may work more smoothly if you activate the virtualenv before starting them.

Pre-commit hooks

The pre-commit hooks, which are automatically installed by running the make init command on set up, ensure that files are valid and properly formatted. Some pre-commit hooks may automatically reformat code or update files:

blacken-docs

Automatically formats Python code in reStructuredText documentation and docstrings.

ruff

Lint Python code and attempt to automatically fix some problems.

uv-lock

Update the uv.lock file if dependencies in pyproject.toml have changed.

When these hooks fail, your Git commit will be aborted. To proceed, stage the new modifications and proceed with your Git commit.

Building the UI

Before running tests, you must build the UI. The Gafaelfawr UI is written in JavaScript and contained in the ui subdirectory. To build it, run (from the top level):

make ui

You will need to have Node.js and npm installed. The easiest way to do this is generally to use nvm. Gafaelfawr provides an .nvmrc file that sets the version of Node.js to what is currently used to build the UI in GitHub Actions for the official Docker image.

Running tests

To test all components of Gafaelfawr other than the Kubernetes operator (see below), run tox, which tests the library the same way that the CI workflow does:

uv run tox run

This uses tox-docker to start PostgreSQL and Redis Docker containers for the tess to use, so Docker must be installed and the user running tox must have permission to create Docker containers.

To run the Selenium tests, you will need to have the chromedriver package installed. On Debian and Ubuntu systems, you can install this with apt install chromium-driver.

To run the tests with coverage analysis and generate a report, run:

uv run tox run -e py-coverage,coverage-report

To see a listing of test environments, run:

uv run tox list

To run a specific test or list of tests, you can add test file names (and any other pytest options) after -- when executing the py or py-full tox environment. For example:

uv run tox run -e py -- tests/handlers/api_tokens_test.py

You can run a specific test function by appending two colons and the function name to the end of the file name.

Testing the Kubernetes operator

To test the Kubernetes operator, you must have a Kubernetes cluster available that is not already running Gafaelfawr. This is only tested with Minikube, which is the approach used by CI.

Warning

The default Kubernetes credentials in your local Kubernetes configuration will be used to run the tests, whatever cluster that points to. In theory, you can use a regular Kubernetes cluster and only test namespaces starting with test- will be affected.

In practice, this is not tested, and it is possible the tests will damage or destroy other applications or data running on the same Kubernetes cluster.

If you want to run these tests manually rather than via CI, using Minikube for tests and carefully verifying that the default Kubernetes credentials are for the Minikube environment is strongly encouraged.

To set up Minikube:

  1. Install Minikube for your platform.

  2. Start a cluster using the Docker driver with the minimum recommended resources:

    minikube start --driver=docker --cpus=4 --memory=8g --disk-size=100g  --kubernetes-version=1.21.5

    The --kubernetes-version option can be used to specify the Kubernetes version to use.

  3. Enable the NGINX Ingress Controller using the Minikube ingress addon:

    minikube addons enable ingress

To run all of the tests including Kubernetes tests, first check that your default Kubernetes environment is the one in which you want to run tests:

kubectl config current-context

Then, run:

uv run tox run -e py-full

Add the coverage-report environment to also get a test coverage report.

Running a development server

Properly and fully testing Gafaelfawr requires deploying it in a Kubernetes cluster and testing its interactions with Kubernetes and the NGINX ingress. Gafaelfawr therefore doesn’t support starting a local development server; that would only allow limited testing of the API and UI, and in practice we never used that ability when we supported it.

Therefore, to run a development version of Gafaelfawr for more thorough manual testing, deploy it in a development Phalanx environment. See the Phalanx documentation for more details on how to do this.

You will generally want to override the Gafaelfawr image and pull policy in your Phalanx development branch to point at the Docker image for your development version. Do this by adding the following to the appropriate values-environment.yaml file:

image:
  tag: tickets-DM-XXXXX
  pullPolicy: Always

Replace the tag with the name of your development branch. Slashes will be replaced with underscores.

Note

Be sure you use a branch naming pattern that will cause the Gafaelfawr GitHub Actions configuration to build and upload a Docker image. By default, this means the branch name must begin with tickets/. You can change this in .github/workflows/ci.yaml under the build step.

Updating dependencies

All Gafaelfawr dependencies are configured in pyproject.toml like a regular Python package. Runtime dependencies are configured in project.dependencies, and development dependencies are configured under dependency-groups. The following dependency groups are used:

dev

Dependencies required to run the test suite, not including the dependencies required to run tox itself.

docs

Dependencies required to build the documentation.

lint

Dependencies required to run pre-commit and to lint the code base.

tox

Dependencies required to run tox.

typing

Dependencies required to run mypy

These dependency groups are used by the tox configuration in tox.ini to install the appropriate dependencies based on the tox action. The development virtualenv in .venv will have all of these dependency groups installed so the developer can freely use commands such as ruff and mypy.

A frozen version of all of these dependencies is managed by uv in the file uv.lock. This is used to pin all dependencies so that they only change when a developer intends to update them and is prepared to run tests to ensure nothing broke.

After changing any dependency, run make update-deps to rebuild the uv.lock file and update any JavaScript dependencies. To also update the development virtualenv, run make update instead.

Temporary Git dependencies

By default, all Python dependencies are retrieved from PyPI.

Sometimes during development it may be useful to test Gafaelfawr against an unreleased version of one of its dependencies. uv supports this by setting a dependency source.

For example, to use the current main branch of Safir instead of the latest released version, add the following to the end of pyproject.toml:

[tool.uv.sources]
safir = { git = "https://github.com/lsst-sqre/safir", branch = "main", subdirectory = "safir" }

The uv add command can be used to configure these sources if desired. As always, after changing dependencies, run make update or make update-deps. Gafaelfawr will now use the unreleased version of Safir.

Do not release new non-alpha versions of Gafaelfawr with these types of Git dependencies. The other package should be released first before a new version of Gafaelfawr is released.

Creating database migrations

Gafaelfawr uses Alembic to manage and perform database migrations. Alembic is invoked automatically when the Gafaelfawr server is started.

Whenever the database schema changes, you will need to create an Alembic migration. To do this, follow the Safir schema migration documentation. Add uv run to the start of all tox commands shown there, unless you have activated the Gafaelfawr development virtualenv.

Building documentation

Documentation is built with Sphinx:

uv run tox run -e docs

The build documentation is located in the docs/_build/html directory.

To check the documentation for broken links, run:

uv run tox run -e docs-linkcheck

Updating the change log

Gafaelfawr uses scriv to maintain its change log.

When preparing a pull request, run uv run scriv create. This will create a change log fragment in changelog.d. Edit that fragment, removing the sections that do not apply and adding entries fo this pull request. You can pass the --edit flag to uv run scriv create to open the created fragment automatically in an editor.

Change log entries use the following sections:

  • Backward-incompatible changes

  • New features

  • Bug fixes

  • Other changes (for minor, patch-level changes that are not bug fixes, such as logging formatting changes or updates to the documentation)

Versioning assumes that Gafaelfawr is installed via Phalanx, so changes to its internal configuration file do not count as backward-incompatible chnages unless they require changes to Helm values.yaml files.

Do not include a change log entry solely for updating pinned dependencies, without any visible change to Gafaelfawr’s behavior. Every release is implicitly assumed to update all pinned dependencies.

These entries will eventually be cut and pasted into the release description for the next release, so the Markdown for the change descriptions must be compatible with GitHub’s Markdown conventions for the release description. Specifically:

  • Each bullet point should be entirely on one line, even if it contains multiple sentences. This is an exception to the normal documentation convention of a newline after each sentence. Unfortunately, GitHub interprets those newlines as hard line breaks, so they would result in an ugly release description.

  • Avoid using too much complex markup, such as nested bullet lists, since the formatting in the GitHub release description may not be what you expect and manually editing it is tedious.

Style guide

Code

  • Gafaelfawr follows the SQR-072 Python style guide.

  • The code formatting follows PEP 8, though in practice lean on Black and isort to format the code for you.

  • Use PEP 484 type annotations. The uv run tox run -e typing command, which runs mypy, ensures that the project’s types are consistent.

  • Gafaelfawr uses the Ruff linter with most checks enabled. Its primary configuration is in ruff-shared.toml, which should be an exact copy of the version from the FastAPI Safir app template. Try to avoid noqa markers except for issues that need to be fixed in the future. Tests that generate false positives should normally be disabled, but if the lint error can be avoided with minor rewriting that doesn’t make the code harder to read, prefer the rewriting.

  • Write tests for pytest.

Documentation