Documentation For Developers

Cloud Custodian makes every effort to provide comprehensive documentation. Any new features you add should be documented.

The documentation is built using sphinx. The documentation is written using reStructured Text (rst). The sphinx documentation contains a useful introduction to rst syntax.

Find the Documentation

The root of the documentation is located in the docs directory. Within the documentation, topics are organized according into the following main areas:

  • Overview

  • Quickstart

  • AWS

  • Azure

  • Developer

In addition, the api documentation will be built from docstrings on classes and methods in source code. The rst files for these may be found in the generated subdirectory.

Edit the Documentation

In most cases, documentation edits will be made in docstrings on source code. Docstrings should be written following the principles of pep 257. Within docstrings, rst directives allow for highlighting code examples:

class AutoTagUser(EventAction):
    """Tag a resource with the user who created/modified it.

    .. code-block:: yaml

      policies:
        - name: ec2-auto-tag-ownercontact
          resource: ec2
          description: |
            Triggered when a new EC2 Instance is launched. Checks to see if
            it's missing the OwnerContact tag. If missing it gets created
            with the value of the ID of whomever called the RunInstances API
          mode:
            type: cloudtrail
            role: arn:aws:iam::123456789000:role/custodian-auto-tagger
            events:
              - RunInstances
          filters:
           - tag:OwnerContact: absent
          actions:
           - type: auto-tag-user
             tag: OwnerContact

    There's a number of caveats to usage. Resources which don't
    include tagging as part of their api may have some delay before
    automation kicks in to create a tag. Real world delay may be several
    minutes, with worst case into hours[0]. This creates a race condition
    between auto tagging and automation.

    In practice this window is on the order of a fraction of a second, as
    we fetch the resource and evaluate the presence of the tag before
    attempting to tag it.

    References

     CloudTrail User
     https://docs.aws.amazon.com/awscloudtrail/latest/userguide/cloudtrail-event-reference-user-identity.html
    """

Render the Documentation

In general, you should use tox to build the documentation:

$ tox -e docs

This command will clean previously built files and rebuild the entire documentation tree.

When developing, you may prefer to build only those files you have edited. To do so, use the following command:

$ make -f docs/Makefile.sphinx html