Contributing

Prometheus uses GitHub to manage reviews of pull requests.

If you have a trivial fix or improvement, go ahead and create a pull request, addressing (with @...) the maintainer of this repository (see MAINTAINERS.md) in the description of the pull request.
If you plan to do something more involved, first discuss your ideas on our mailing list. This will avoid unnecessary work and surely give you and us a good deal of inspiration.
Before your contributions can be landed, they must be signed off under the Developer Certificate of Origin which asserts you own and have the right to submit the change under the open source licence used by the project.

Testing

Submitted changes should pass the current tests, and be covered by new test cases when adding functionality.

Run the tests locally using tox which executes the full suite on all supported Python versions installed.
Each pull request is gated using Travis CI with the results linked on the github page. This must pass before the change can land, note pushing a new change will trigger a retest.

Code style should follow PEP 8 generally, and can be checked by running: tox -e flake8.
Import statements can be automatically formatted using isort.