Documentation Guide

Writing Documentation

Docs are generated using Sphinx.

Documentation is written in reStructuredText, or in MyST Markdown.

In reStructuredText documents, to create the section hierarchy (mapped in HTML to <h1> through <h5>) use the underline characters in this order: =, - ", ', ^.

The documentation build process is stored in the Makefile. Building docs requires Python3 to be installed, and most steps will automatically create virtualenv (venv_docs) which contains the required tools.

Running make html will generate HTML formatted documentation in _build/html, which you can view with a web browser.

Before submitting the docs or to verify the docs in CI workflow, run make test, which will check lint, spelling, and that links inside the site are not broken. If there are additional words that are correctly spelled but not in the dictionary (acronyms, trademarks, etc.) please add them to the dict.txt file. You may also need to install the enchant C library using your system’s package manager for the spelling checker to function properly.

Referencing other Documentation sites

Other Sphinx-built documentation, both ONF and non-ONF can be linked to using Intersphinx.

You can see all link targets available on a remote Sphinx’s docs by running:

python -msphinx.ext.intersphinx http://other_docs_site/objects.inv

See the this document for Intersphinx examples.

Adding Documentation from other Repos

Documentation written in other git repos can be included in the documentation generated with this by performing the following steps:

  1. Edit the space-separated list OTHER_REPO_DOCS in the Makefile to include the name of the other repo. These repos will be checked out into repos and then copied into the main directory with the repo name (this is required for the versioning process to work).

  2. Add the name of the repo to the .gitignore file so it won’t be checked in.

  3. Add a line for the repo in git_refs with the repo name, path, and git ref (usually master) to be used.

  4. Add the paths to the documentation files in the other repo to the index.rst file.

  5. Build the docs with make html and verify that there aren’t any warnings and the docs have been added. If you need to exclude specific files from the docs, you should add them to the exclude_patterns list in

Creating new versions of Docs

To change the version shown on the built site, change the contents of the VERSION file. As a part of committing the code in the CI process, the VERSION should be checked for uniqueness, and if it’s a SemVer version, turned into a git tag.

There is a make multiversion target which will build all git-tagged versions and branches published on the remote to _build. This will use a fork of sphinx-multiversion to build multiple versions for the site.

If you’re adding documentation from other repos and you want to hold to a specific version, run make freeze and put the output in the git_refs file - this will cause that specific commit hash of the other repo to be checked out when building the docs for a specific version.

Adding Graphs and Diagrams

Multiple tools are available to render inline text-based graphs definitions and diagrams within the documentation. This is preferred over images as it’s easier to change and see changes over time as a diff.

Graphviz supports many standard graph types.

If you have hand-created charts, prefer to use in SVG format and embed the diagram source in the image, which will allow it to be edited later.