Contributing to Seldon Core

Before opening a pull request consider:

• Is the change important and ready enough to ask the community to spend time reviewing?
• Have you searched for existing, related issues and pull requests?
• Is the change being proposed clearly explained and motivated?

When you contribute code, you affirm that the contribution is your original work and that you license the work to the project under the project’s license unless otherwise agreed by you and Seldon in writing. Whether or not you state this explicitly, by submitting any copyrighted material via pull request, email, or other means you agree to license the material under the project’s license or, in the case of contributions made under the BSL license, a separate Contributor License Agreement (“CLA”) and warrant that you have the legal authority to do so.  Submission of any copyrighted material for contribution of a project does not guarantee that such submission will be accepted by Seldon, and Seldon may reject any potential contribution in its sole discretion.

Release notes

Our process to manage release notes is modeled after how the Kubernetes project handles them. This process can be separated into 2 separate phases:

• Adding notes on each PR. Happens at PR creation time.
• Compiling all PR notes before a release. Happens at release time.

Adding notes on each PR

When a PR is created, a Prow / Lighthouse plugin will check if there is a populated release-note block in the PR body such as:

“`release-note

Some public-facing release note.

“`

If there isn’t, the PR will be labeled as do-not-merge/release-note-label-needed. Note that to speed things up, the default PR template will create an empty release-notes block for you. For PRs that don’t need public-facing release notes (e.g. fixes on the integration tests), you can use the /release-note-none Prow command.

Conventions

There are a number of conventions that we can use so that the changes are more semantic. These are mainly based around keywords which will affect how the release notes will get displayed.

• Use the words Added, Changed, Fixed, Removed or Deprecated to describe the contents of the PR. For example:

“`release-note

Added metadata support to Python wrapper

“`

• Use the expression Action required to describe breaking changes. For example:

“`release-note

Action required: The helm value `createResources` has been renamed

`managerCreateResources`.

“`

Compiling all PR notes before a release

At release time, there is a release-notes command which crawls over all the PRs between 2 particular tags (e.g. v1.1.0 to v1.2.0), extracting the release-notes blocks. These blocks can then be used to generate the final release notes.

Coding conventions

We use pre-commit to handle a number of Git hooks which ensure that all changes to the codebase follow Seldon’s code conventions. It is recommended to set these up before making any change to the codebase. Extra checks down the line will stop the build if the code is not compliant to the style guide of each language in the repository.

To install it, follow the official instructions. Once installed, run:

$ pre-commit install

This will read the hooks defined in .pre-commit-config.yaml and install them accordingly on your local repository.

Java

To format our Java code we follow Google’s Java style guide. To make sure that the codebase remains consistent, we use checkstyle as part of the mvn validate lifecycle.

To integrate these on your local editor, you can follow the official instructions to configure checkstyle locally and to set-up google-java-format.

Python

To format our Python code we use black, the heavily opinionated formatter.

To integrate it on your local editor, you can follow the official instructions to set-up black.

Tests

Regardless of the package you are working on, we abstract the main tasks to a Makefile. Therefore, in order to run the tests, you should be able to just do:

$ make test

Python

We use pytest as our main test runner. However, to ensure that tests run on the same version of the package that final users will download from pip and pypi.org, we use tox on top of it. To install both (plus other required plugins), just run:

$ make install_dev

Using tox we can run the entire test suite over different environments, isolated between them. You can see the different ones we currently use on the setup.cfg file. You can run your tests across all these environments using the standard make test mentioned above. Alternatively, if you want to pass any extra parameters, you can also run tox directly as:

$ tox

One of the caveats of tox is that, as the number of environments grows, so does the time it takes to finish running the tests. As a solution, during local development it may be recommended to run pytest directly on your own environment. You can do so as:

$ pytest

End to End Tests

As part of Seldon Core’s test suite, we also run end to end tests. These spin up an actual Kubernetes cluster using Kind and deploy different SeldonDeployment and resources.

You can learn more about how to run them and how to add new test cases on their dedicated documentation.