Writing Documentation


The Autoware.Auto documentation is created with the doxygen tool based on text files written in markdown; see markdown in doxygen for details.


Verify the documentation builds without errors and appears as desired by building locally first:


At the end of the long output of this command, the entry point is displayed. Open in a web browser

Documentation has been built in: /home/user/AutowareAuto/docs/_build/html/index.html


As a final check before merging, validate that the documentation built in CI is correct by browsing the artifacts of the docs stage of the merge request's build job. The URL will be similar to the following but the build job ID has to be modified

To select the docs with a mouse, first open the pipeline of the merge request on GitLab, then select the docs job:

Select the docs build job

Finally browse the artifact and select the html file(s) modified in the merge request.

Browse the documentation artifact

Markdown guidelines

Lines in markdown shall in general be limited to 100 characters with exceptions when that's impractical; e.g.

  • long links
  • source code

To ease code review, it is recommended that each sentence start on a new line. This doesn't break paragraphs unless a blank line is included.

Code snippets

Start a fenced code block and add the language (cpp, py, bash, xml ...) for syntax highlighting in braces; e.g.,

int main()
  return 0;


Illustrations and screenshots are great to make a point and can save a lot of text. Place an image into the docs/images folder and refer to it as

@image html images/foo.png "image caption"

This way of including ensures that doxygen fails if it cannot find the image. Optionally, one can set e.g. the width of the image in the output in absolute or relative size to prevent a large image from disrupting the reading flow:

@image html images/foo.png "image caption" width=1000px
@image html images/foo.png "image caption" width=50%

Integrating a new document

Add an anchor for a new document; e.g.


After the title and use the anchor to link to other parts of the documentation. A minimal example:

New document {#new-document}
# First section
# Second section

And within another, refer to the new document with:

@ref new-document "See the new document"

Make sure the document is included by an appropriate such that it appears at the desired location; e.g.,

- @subpage new-document

Links from the outside

Documents that link to a section in the doxygen output also need an anchor for that URL to be stable with respect to documentation updates. To that end, the anchor should have a prefix that's unique to the page in which the section lives.



# Foo {#document-foo}

Then the URL is



# Foo

Then the URL could be e.g.

Notice the autotoc_md21 at the end of the URL. Doxygen increments a counter to automatically create URLs for sections without an anchor. If the section Foo is moved or another section added somewhere else, the URL may become invalid.

Documenting a package

Packages shall be accompanied with a design document written in markdown; e.g. in pkg_foo/design/ There can be several files in design/ if needed. The purpose of the design document is to describe the intended behavior of a component. Serving as an entry point for users unfamiliar with that component, it should explain at a sufficient abstraction level.

Documenting source code

All C++ code that is to be consumed by someone else should be declared in header files and should come with doxygen comments including classes, structs, methods, members etc.

Use the imperative to describe each entity. Finish each section with a period ..

For example:

// Analyse input for consistency.
// @param input The input, assumed `>= 1.2`.
// \throws A `std::invalid_argument` if invalid.
explicit class Foo(double input);
// \return `true` if the input is valid.
bool valid() const;

Comments inside code

Add comments where the code is not self-explanatory. When adding comments, think about renaming/restructuring to make the code self-explanatory.

Don't add this comment as it doesn't provide useful information

// distance
double distance = 3.2;