Contributing guidelines

Estimated reading time: 6 minutes

The live docs are published from the master branch. Therefore, you must create pull requests against the master branch for all content updates. This includes:

  • Conceptual and task-based information
  • Restructuring / rewriting
  • Doc bug fixing
  • Fixing typos, broken links, and any grammar errors

There are two ways to contribute a pull request to the docs repository:

  1. You can click Edit this page option in the right column of every page on https://docs.docker.com/.

    This opens the GitHub editor, which means you don’t need to know a lot about Git, or even about Markdown. When you save, Git prompts you to create a fork if you don’t already have one, and to create a branch in your fork and submit the pull request.

  2. Fork the docs GitHub repository. Suggest changes or add new content on your local branch, and submit a pull request (PR) to the master branch.

    This is the manual, more advanced version of clicking ‘Edit this page’ on a published docs page. Initiating a docs changes in a PR from your own branch gives you more flexibility, as you can submit changes to multiple pages or files under a single pull request, and even create new topics.

    For a demo of the components, tags, Markdown syntax, styles, etc we use at https://docs.docker.com/, see the Useful components section.

Important files

Here’s a list of some of the important files:

  • /_data/toc.yaml defines the left-hand navigation for the docs
  • /js/docs.js defines most of the docs-specific JS such as the table of contents (ToC) generation and menu syncing
  • /css/style.scss defines the docs-specific style rules
  • /_layouts/docs.html is the HTML template file, which defines the header and footer, and includes all the JS/CSS that serves the docs content

Files not edited here

Some files and directories are maintained in the upstream repositories. You can find a list of such files in _config_production.yml. Pull requests against these files will be rejected.

Pull request guidelines

Help us review your PRs more quickly by following these guidelines.

  • Try not to touch a large number of files in a single PR if possible.
  • Don’t change whitespace or line wrapping in parts of a file you are not editing for other reasons. Make sure your text editor is not configured to automatically reformat the whole file when saving.
  • We highly recommend that you build and test the docs locally before submitting a PR.
  • A Netlify test runs for each PR that is against the master branch, and deploys the result of your PR to a staging site. The URL will be available at in the Conversation tab. Check the staging site to verify how your changes look and fix issues, if necessary.

Collaborate on a pull request

Unless the PR author specifically disables it, you can push commits into another contributor’s PR. You can do it from the command line by adding and fetching their remote, checking out their branch, and adding commits to it. Even easier, you can add commits from the Github web UI, by clicking the pencil icon for a given file in the Files view.

If a PR consists of multiple small addendum commits on top of a more significant one, the commit will usually be “squash-merged”, so that only one commit is merged into the master branch. In some scenarios where a squash and merge isn’t appropriate, all commits are kept separate when merging.

Per-PR staging on GitHub

A Netlify test runs for each PR created against the master branch and deploys the result of your PR to a staging site. When the site builds successfully, you will see a comment in the Conversation tab in the PR stating Deploy Preview for docsdocker ready!. Click the Browse the preview URL and check the staging site to verify how your changes look and fix issues, if necessary. Reviewers also check the staged site before merging the PR to protect the integrity of the docs site.

Build and preview the docs locally

On your local machine, clone the docs repository:

git clone https://github.com/docker/docs.git
cd docs

Then, build and run the documentation using Docker Compose

docker compose up -d --build

You need Docker Compose to build and run the docs locally. Docker Compose is included with Docker Desktop. If you don’t have Docker Desktop installed, follow the instructions to install Docker Compose.

When the container is built and running, visit http://localhost:4000 in your web browser to view the docs.

To rebuild the docs after you made changes, run the docker compose up command again. This rebuilds the docs, and updates the container with your changes:

docker compose up -d --build

To stop the staging container, use the docker compose down command:

docker compose down

Build the docs with deployment features enabled

The default configuration for local builds of the documentation disables some features to allow for a shorter build-time. The following options differ between local builds, and builds that are deployed to docs.docker.com:

  • search auto-completion, and generation of js/metadata.json
  • Google Analytics
  • page ratings
  • sitemap.xml generation
  • minification of stylesheets (css/style.css)
  • adjusting “edit this page” links for content in other repositories

If you want to contribute in these areas, you can perform a “production” build locally. To preview the documentation with deployment features enabled, set the JEKYLL_ENV environment variable when building the documentation:

JEKYLL_ENV=production docker compose up --build

When the container is built and running, visit http://localhost:4000 in your web browser to view the docs.

To rebuild the docs after you make changes, repeat the steps above.

Test the docs locally

We use a command-line tool called vale to check the style and help you find errors in your writing. We highly recommend that you use vale to lint your documentation before you submit your pull request.

You can run vale as a stand-alone tool using the command-line, or you can integrate it with your editor to get real-time feedback on your writing.

To get started, follow the vale installation instructions for your operating system. To enable the vale integration for your editor, install the relevant plugin:

The vale rules that implement the Docker style guide are included in the Docker docs repository, in the .github/vale directory. Vale will automatically apply these rules when invoked in this repository.

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