1535452 - (first-class-docs) [meta] Make writing and reading our in-tree documentation a first class experience

Status: NEW

(Developer Infrastructure :: Source Documentation, enhancement)

Description

[Andrew Halberstadt [:ahal]]

Despite being critically important, our in-tree documentation system is neglected, without owner and without direction. Writing documentation can be painful, and reading the output of the documentation is even more painful:
https://firefox-source-docs.mozilla.org/

This bug is going to track all the issues we need to fix to improve the status quo. It will also act as the launching point for a GSoC proposal I've submitted (which is my main motivation for filing this meta bug).

Comment 1

[Andrew Halberstadt [:ahal]]

This comment is a description of how the doc system works with some links to code. This is a very general overview that is intended to provide context for anyone working on any of the dependencies filed against this meta bug.

Registration

The goal of our doc system is to allow individual teams and developers the ability to create and maintain their own domain specific documentation. We don't want to act as gatekeepers. In order for this to work, we need some mechanism for developers to register a doc dir.

Documentation gets registered by developers via moz.build files. For example:
https://searchfox.org/mozilla-central/rev/4763b8d576ce52625d245d1ab6d9404ea025b026/tools/moz.build#53

There are two variables, SPHINX_TREES and SPHINX_PYTHON_PACKAGE_DIRS and some information on them can be found here:
https://searchfox.org/mozilla-central/rev/4763b8d576ce52625d245d1ab6d9404ea025b026/python/mozbuild/mozbuild/frontend/context.py#2004

Generation

Documentation is generated using sphinx with some custom tooling to hook in all of the directories that are registered via moz.build. Aside from sphinx itself, there are 3 pieces to this stage:

1. mach command
   This is the command line entry point for generating and uploading docs. It is mostly just a thin wrapper around sphinx-build, but also acts like the glue that holds the system together.

2. custom sphinx extension
   A custom sphinx extension that acts as a hook from which we can run all our customized operations before the regular 'sphinx-build' kicks in. This module is registered in the main conf.py. This extension adds a couple custom sphinx directives as well, but otherwise isn't very interesting.

3. moztreedocs
   A little python module containing the meat of the custom generation code. It is invoked from sphinx.py above and is responsible for reading the moz.build variables and copying all of the relevant source files into a staging directory in the objdir. Once all the source files have been copied, sphinx-build will run against the staging dir.

At a high level, the doc generation process will go something like this:

1. User runs mach doc or mach doc <subdir>
2. Mach command runs sphinx-build with tools/docs/conf.py as the config file.
3. The mozbuild.sphinx extension is registered in this config file.
4. This extension has a setup hook which calls into moztreedocs.
5. moztreedocs reads all the moz.build sphinx variables and copies all the source files to a staging dir.
6. The mozbuild.sphinx extension gets sphinx-build to build the docs from this staging directory.
7. sphinx-build resumes as normal, typically a directory next to the staging dir will contain the html output.

Publication

Publishing docs is a separate step from generation, but uses the same mach command: mach doc --upload. This step is much simpler than the generation one. The docs are hosted on a static Amazon S3 bucket behind this domain:
https://firefox-source-docs.mozilla.org/

The mach doc --upload command uses Amazon's boto3 library to push the output dir generated in step 7 above up to the static server:
https://searchfox.org/mozilla-central/source/tools/docs/moztreedocs/upload.py

And that's it.

Continuous Integration

While it is possible to generate docs locally, publishing requires special credentials. Generation and publication are handled by two separate tasks (Doc and DocUp respectively). They are defined here:
https://searchfox.org/mozilla-central/source/taskcluster/ci/source-test/doc.yml

These tasks will run whenever someone modifies a doc source file, so changes to the documentation should be automatically picked up and published once the patch lands to mozilla-central. While it's nice to have this automated system, we do still care about running mach doc locally as developers will typically want to see how their modifications look before pushing.

Comment 2

[Doan Vo]

(In reply to Andrew Halberstadt [:ahal] from comment #0)
HI @Andrew Halberstadt,
I'm a newcomer. I read description of this bug but I don't know how to start.
May you help me with some simple guidelines?
Thank you
Doan

Comment 3

[Shivam Singhal [ :championshuttler ]]

I'm a newcomer. I read description of this bug but I don't know how to start.

Description of the bug explain the architecture of our docs infra and how it runs.

May you help me with some simple guidelines?

After setting up Firefox Docs locally, you can look into the bugs on which this meta bug is depended. If you have some questions feel free to ask in #firefox-source-docs in chat.mozilla.org