Hacking on 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.

Do these things once

  • To contribute, 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 the CLA and prompted for ‘Project contact’ or ‘Canonical Project Manager’ enter ‘Josh Powers’.

    For existing contributors who’ve already signed the agreement, we can verify the link between your Launchpad account and your GitHub account by creating a branch with both your Launchpad and GitHub usernames into both 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. We will reply to the email address associated with your Launchpad account that you’ve been clear to contribute to cloud-init on GitHub.

    If your company has signed the CLA for you, please contact us to help in verifying which launchad/GitHub accounts are associated with the company. For any questions or help with the process, please email:

    Josh Powers with the subject: Cloud-Init CLA

    You also may contanct user powersj in #cloud-init channel via IRC freenode.

  • 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.

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

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
  • Run unit tests and lint/formatting checks with tox:

  • Push your changes to your personal GitHub repository:

    git push -u GH_USER my-topic-branch
  • Use your browser to create a merge request:

    • Open the branch on GitHub

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


    • 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
      74 characters followed by a blank line, and then one or more
      paragraphs 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 trunk.
      LP: #1

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

    • Click ‘Create Pull Request`

Then, someone in the Ubuntu Server team will review your changes and follow up in the pull request.

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


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

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).