Document Agent Config Yaml keyword reference
Problem
GitLab Agent for Kubernetes has config.yaml for agent configuration. Currently this config syntax is described per use case, which you can find in GitOps workflow and CI/CD workflow, however, since the pages are separated, it's hard for users to know what keywords are available at the glance. Also, there seems undocumented keywords, such as ci_access: access_as: agent: {}
.
Similarly for GitLab developers, it's hard to find if the feature implementation on a specific keyword is complete or not. For example, ci_user
keyword already exists in GitLab Rails, however, the whole implementation (maybe KAS part) seems not complete.
Related https://gitlab.slack.com/archives/C04SS157XSQ/p1680170339418589
Proposal
Introduce a keyword reference doc like .gitlab-ci.yml keyword reference.
More examples: