Drupal Module Documentation

Drupal Module Documentation (MkDocs)

Overview

Drupal contrib modules publish documentation to GitLab Pages through the drupal.org gitlab_templates pipeline. The docs live in a docs/ folder, MkDocs (Material theme) builds them, and the pages CI job deploys them to https://project.pages.drupalcode.org/<data_name>. This skill writes that documentation, builds the docs/ structure, and sets up or edits mkdocs.yml and .gitlab-ci.yml.

The data name is the module's project machine name: the .info.yml prefix and the git repo name (git.drupalcode.org/project/<data_name>).

Writing Style

Documentation should read like a maintainer wrote it, not like an AI generated it. Apply these to all prose in the docs (this matches the drupal-project-description skill).

• No em dashes and no en dashes. Use a comma, semicolon, colon, period, or parentheses, or rewrite. Plain hyphens are fine only in compound words.
• Active voice.
• Wry, plain, and direct. No flowery or superfluous language.
• No contrastive constructions such as "this isn't X, it's Y." State what the thing is.
• No marketing hype, subjective qualifiers, or value judgments. State facts a user can verify.
• No emojis in the prose.
• Terse and high in signal. Cut padding and throat-clearing intros.

Workflow

1. Read the module first. Get the data name and human name from <data_name>.info.yml. Read the existing README, docs/ (if any), config forms, routing, and services to learn what the module actually does before writing about it.

2. Put all docs under docs/. Entry point is docs/index.md. Never place doc pages elsewhere.

3. Set up or edit mkdocs.yml at the repo root. Adapt the template in mkdocs.yml in this skill folder. Set site_name, set site_url to https://project.pages.drupalcode.org/<data_name>, and keep theme: name: material. Build the nav from the structure below. The template ships the markdown_extensions and plugins config the drupal.org ai project uses (see "MkDocs plugins and extensions"), including the mermaid fence for diagrams. Reach for mermaid whenever a flow, architecture, plugin relationship, or state machine is clearer as a diagram than as prose.

4. Handle .gitlab-ci.yml (see the section below).

5. Write the docs structure (see Documentation Structure).

6. Point the README at the docs. Append a short section to the end of the module's README.md telling readers the full documentation lives under docs/ and is published on GitLab Pages. Keep the rest of the README intact.

   
   ## Documentation
   
   Full documentation is under [`docs/`](docs/) and published at
   https://project.pages.drupalcode.org/<data_name>.
   

7. Screenshots (optional). Ask the user first: to capture screenshots, they should install the vercel/agent-browser skill and tell you where their Drupal site is reachable (the base URL and any login). If they already have Puppeteer or another browser tool, use that instead. Skip screenshots silently if none is available; do not fabricate image paths.

8. After the first push, tell the user to open https://git.drupalcode.org/project/<data_name>/pages and turn off the unique ID (the "User unique domain" toggle under Deploy > Pages > Domains & settings). With it off the URL is the clean https://project.pages.drupalcode.org/<data_name>, which is what site_url should match.

.gitlab-ci.yml

If the file is missing completely, add the standard drupal.org template:

include:
  - project: $_GITLAB_TEMPLATES_REPO
    ref: $_GITLAB_TEMPLATES_REF
    file:
      - '/includes/include.drupalci.main.yml'
      - '/includes/include.drupalci.variables.yml'
      - '/includes/include.drupalci.workflows.yml'

Tell the user this template also runs the full test and lint suite (PHPUnit, PHPCS, PHPStan, ESLint, Stylelint, Cspell, Composer lint, Nightwatch), not only the docs pages job. Ask whether they want to keep the tests or disable them and run only pages. If they want pages only, add a variables block that skips the test jobs:

variables:
  SKIP_COMPOSER_LINT: '1'
  SKIP_CSPELL: '1'
  SKIP_ESLINT: '1'
  SKIP_NIGHTWATCH: '1'
  SKIP_PHPCS: '1'
  SKIP_PHPSTAN: '1'
  SKIP_PHPUNIT: '1'
  SKIP_STYLELINT: '1'

Leave SKIP_PAGES unset (or '0') so the docs still deploy.

If the file already exists, do not overwrite it. Confirm the three include files are present, ensure SKIP_PAGES is not set to '1', and leave the rest alone.

Pages-job variables you can set when needed: _MKDOCS_STRICT ('0' turns off strict link checking), _MKDOCS_EXTRA (extra mkdocs args), _PAGES_FORCE_REBUILD ('1' forces a rebuild).

MkDocs plugins and extensions

The template mkdocs.yml mirrors the config the drupal.org ai project uses (git.drupalcode.org/project/ai/-/blob/1.x/mkdocs.yml):

• markdown_extensions: attr_list, md_in_html, pymdownx.blocks.caption, and pymdownx.superfences with a mermaid custom fence, alongside the usual admonition, toc, and pymdownx.highlight.
• plugins: search and include-markdown (https://github.com/mondeja/mkdocs-include-markdown-plugin), which embeds one markdown file into another with {% include-markdown "file.md" %}.

Two of these have install implications:

Mermaid needs nothing extra. The Material theme bundles mermaid.js and renders any ```mermaid block through the superfences custom_fences entry. No pip package, no extra_javascript. Use it for diagrams:

```mermaid
flowchart LR
    Request --> Plugin --> Response
```

include-markdown is a separate pip package (mkdocs-include-markdown-plugin) that is not bundled with mkdocs-material. The standard drupal.org gitlab_templates pages job only runs pip install mkdocs-material, so the build fails with an unknown-plugin error unless you install it. Add a before_script to the pages job in the module's .gitlab-ci.yml (this merges with, and does not replace, the template's job script):

pages:
  before_script:
    - pip install mkdocs-include-markdown-plugin

Add any other non-Material plugin (for example mkdocs-glightbox) to that same pip install line. If you keep the template's default plugins (search plus include-markdown), you must add this before_script; if you drop include-markdown from mkdocs.yml, you can drop the before_script too. To build locally, run pip install mkdocs-material mkdocs-include-markdown-plugin first.

Documentation Structure

Build docs/ roughly like this, dropping pages that don't apply and splitting usage into more pages when a module is large:

docs/
  index.md            # what the module is (mirror the one-paragraph project preview), key features
  installation.md     # composer require, drush en, dependencies
  configuration.md    # settings, permissions, config forms
  usage/              # how to use each feature, one page per feature area
    <feature>.md
  developers/         # only if there is an API or plugin system (see below)
    index.md          # extension points overview
    <plugin-type>.md  # how to add a plugin, hook, or event subscriber
  extending-modules.md # list of modules that extend this one, if any exist

Reflect the same structure in mkdocs.yml nav.

For Developers section

Add a separate For Developers section (the docs/developers/ pages, its own top-level nav entry) only if the module ships an extension surface. Signs of one:

• an *.api.php file documenting hooks
• a plugin system: src/Plugin/, plugin managers in *.services.yml, annotation or attribute plugin definitions
• events and event subscribers meant for others to hook into

Keep this section outside the usage pages so a site builder reading how to use the module is not mixed up with a developer reading how to extend it. Document the plugin types, the hooks in the .api.php file, relevant services, and a short example of adding one.

Modules extending this one

If other modules extend this module, add extending-modules.md listing them, each with a link to its drupal.org project page and one line on what it adds. Skip the page if there are none.

Common Mistakes