Wikis development guidelines

Wiki functionality in GitLab uses Git repositories as the storage backend and is accessed from the Rails app through Gitaly RPC calls.

You can access wikis through:

Involved Gems

Some notable gems that are used for wikis are:

Component	Description	Gem name	GitLab project	Upstream project
`gitlab`	Markup renderer, depends on various other gems	`gitlab-markup`	`gitlab-org/gitlab-markup`	`github/markup`

Wiki rendering

When rendering wiki pages, we use a custom Banzai pipeline. This pipeline adds wiki-specific markup, such as the [[link]] syntax.

Model classes

The Wiki class is the main abstraction around a wiki repository. You must initialize it with a container, which can be either a Project or Group:

classDiagram
  Wiki --> ProjectWiki
  Wiki --> GroupWiki

  class Wiki {
    #container
    #repository
  }

  class ProjectWiki {
    #project → #container
  }

  class GroupWiki {
    #group → #container
  }

Some models wrap similar classes from Gitaly:

Rails Model	Gitaly Class
`Wiki`	`Gitlab::Git::Wiki`
`WikiPage`	`Gitlab::Git::WikiPage`, `Gitlab::Git::WikiPageVersion`
	`Gitlab::Git::WikiFile`

Only some data is persisted in the database:

Model	Description
`WikiPage::Meta`	Metadata for wiki pages
`WikiPage::Slug`	Current and previous slugs of wiki pages
`ProjectRepository`	Gitaly storage data for project wikis
`GroupWikiRepository`	Gitaly storage data for group wikis

Attachments

The web UI uploads attachments through the REST API, which stores the files as commits in the wiki repository.