Contributing to cloud-init
**************************

This document describes how to contribute changes to cloud-init.
It assumes you have a `GitHub`_ account, and refers to your GitHub user
as ``GH_USER`` throughout.

Submitting your first pull request
==================================

Summary
-------

Before any pull request can be accepted, you must do the following:

* Sign the Canonical `contributor license agreement`_
* Add your Github username (alphabetically) to the in-repository list that we use
  to track CLA signatures:
  `tools/.github-cla-signers`_
* Add or update any `unit tests`_ accordingly
* Add or update any `integration tests`_ (if applicable)
* Format code (using black and isort) with `tox -e do_format`
* Ensure unit tests and linting pass using `tox`_
* Submit a PR against the `main` branch of the `cloud-init` repository

.. _unit tests: https://cloudinit.readthedocs.io/en/latest/topics/testing.html
.. _integration tests: https://cloudinit.readthedocs.io/en/latest/topics/integration_tests.html

The detailed instructions
-------------------------

Follow these steps to submit your first pull request to cloud-init:

* To contribute to cloud-init, you must sign the Canonical `contributor
  license agreement`_

  * If you have already signed it as an individual, your Launchpad user
    will be listed in the `contributor-agreement-canonical`_ group.
    (Unfortunately there is no easy way to check if an organization or
    company you are doing work for has signed.)

  * When signing it:

    * ensure that you fill in the GitHub username field.
    * when prompted for 'Project contact' or 'Canonical Project
      Manager', enter 'James Falcon'.

  * If your company has signed the CLA for you, please contact us to
    help in verifying which Launchpad/GitHub accounts are associated
    with the company.

  * For any questions or help with the process, please email `James
    Falcon <mailto:james.falcon@canonical.com>`_ with the subject,
    "Cloud-Init CLA"

  * You also may contact user ``falcojr`` in the ``#cloud-init``
    channel on the Libera IRC network.

* Configure git with your email and name for commit messages.

  Your name will appear in commit messages and will also be used in
  changelogs or release notes.  Give yourself credit!::

    git config user.name "Your Name"
    git config user.email "Your Email"

* Sign into your `GitHub`_ account

* Fork the upstream `repository`_ on Github and clicking on the ``Fork`` button

* Create a new remote pointing to your personal GitHub repository.

  .. code:: sh

    git clone git@github.com:GH_USER/cloud-init.git
    cd cloud-init
    git remote add upstream git@github.com:canonical/cloud-init.git
    git push origin main

* Read through the cloud-init `Code Review Process`_, so you understand
  how your changes will end up in cloud-init's codebase.

* Submit your first cloud-init pull request, adding your Github username to the
  in-repository list that we use to track CLA signatures:
  `tools/.github-cla-signers`_

  * See `PR #344`_ and `PR #345`_ for examples of what this pull
    request should look like.

  * Note that ``.github-cla-signers`` is sorted alphabetically.

  * (If you already have a change that you want to submit, you can
    also include the change to ``tools/.github-cla-signers`` in that
    pull request, there is no need for two separate PRs.)

.. _GitHub: https://github.com
.. _Launchpad: https://launchpad.net
.. _repository: https://github.com/canonical/cloud-init
.. _contributor license agreement: https://ubuntu.com/legal/contributors
.. _contributor-agreement-canonical: https://launchpad.net/%7Econtributor-agreement-canonical/+members
.. _PR #344: https://github.com/canonical/cloud-init/pull/344
.. _PR #345: https://github.com/canonical/cloud-init/pull/345

Transferring CLA Signatures from Launchpad to Github
----------------------------------------------------

For existing contributors who have signed the agreement in Launchpad
before the Github username field was included, we need to verify the
link between your `Launchpad`_ account and your `GitHub`_ account.  To
enable us to do this, we ask that you create a branch with both your
Launchpad and GitHub usernames against both the Launchpad and GitHub
cloud-init repositories.  We've added a tool
(``tools/migrate-lp-user-to-github``) to the cloud-init repository to
handle this migration as automatically as possible.

The cloud-init team will review the two merge proposals and verify that
the CLA has been signed for the Launchpad user and record the
associated GitHub account.

.. note::
   If you are a first time contributor, you will not need to touch
   Launchpad to contribute to cloud-init: all new CLA signatures are
   handled as part of the GitHub pull request process described above.

Do these things for each feature or bug
=======================================

* Create a new topic branch for your work::

    git checkout -b my-topic-branch

* Make and commit your changes (note, you can make multiple commits,
  fixes, more commits.)::

    git commit

* Apply black and isort formatting rules with `tox`_::

    tox -e do_format

* Run unit tests and lint/formatting checks with `tox`_::

    tox

* Push your changes to your personal GitHub repository::

    git push -u origin my-topic-branch

* Use your browser to create a pull request:

  - Open the branch on GitHub

    - You can see a web view of your repository and navigate to the branch at:

      ``https://github.com/GH_USER/cloud-init/tree/my-topic-branch``

  - Click 'Pull Request`
  - Fill out the pull request title, summarizing the change and a longer
    message indicating important details about the changes included, like ::

      Activate the frobnicator.

      The frobnicator was previously inactive and now runs by default.
      This may save the world some day.  Then, list the bugs you fixed
      as footers with syntax as shown here.

      The commit message should be one summary line of less than
      70 characters followed by a blank line, and then one or more
      paragraphs wrapped at 72 characters describing the change and why
      it was needed.

      This is the message that will be used on the commit when it
      is sqaushed and merged into main. If there is a related launchpad
      bug, specify it at the bottom of the commit message.

      LP: #NNNNNNN (replace with the appropriate bug reference or remove
      this line entirely if there is no associated bug)

    Note that the project continues to use LP: #NNNNN format for closing
    launchpad bugs rather than GitHub Issues.

  - Click 'Create Pull Request`

Then, a cloud-init committer will review your changes and
follow up in the pull request.  Look at the `Code Review Process`_ doc
to understand the following steps.

Feel free to ping and/or join ``#cloud-init`` on Libera irc if you
have any questions.

.. _tox: https://tox.readthedocs.io/en/latest/
.. _Code Review Process: https://cloudinit.readthedocs.io/en/latest/topics/code_review.html

Design
======

This section captures design decisions that are helpful to know when
hacking on cloud-init.

Python Support
--------------
Cloud-init upstream currently supports Python 3.6 and above.

Cloud-init upstream will stay compatible with a particular python version
for 6 years after release. After 6 years, we will stop testing upstream
changes against the unsupported version of python and may introduce
breaking changes. This policy may change as needed.

The following table lists the cloud-init versions in which the
minimum python version changed:

================== ==================
Cloud-init version Python version
================== ==================
22.1               3.6+
20.3               3.5+
19.4               2.7+
================== ==================

Cloud Config Modules
--------------------

* Any new modules should use underscores in any new config options and not
  hyphens (e.g. `new_option` and *not* `new-option`).

Tests
-----

Submissions to cloud-init must include testing.  See :ref:`testing` for
details on these requirements.

Type Annotations
----------------

The cloud-init codebase uses Python's annotation support for storing
type annotations in the style specified by `PEP-484`_ and `PEP-526`_.
Their use in the codebase is encouraged.

.. _PEP-484: https://www.python.org/dev/peps/pep-0484/
.. _PEP-526: https://www.python.org/dev/peps/pep-0526/

Feature Flags
-------------

.. automodule:: cloudinit.features
   :members:

.. _tools/.github-cla-signers: https://github.com/canonical/cloud-init/blob/main/tools/.github-cla-signers
