Component Versions and Branches
Versions of a documentation component are stored in branches in a version control repository such as git. The name of the branch itself doesn’t matter. It’s the version property in the component descriptor that determines the name of the version for the component.
Like with software, we use branches to store different versions of the documentation. Branches are ideally suited for managing multiple versions of the same content.
If we didn’t use branches to specify versions, but instead used folders with trailing version numbers, all stuffed in a single branch, then we’d have to explicitly duplicate all the files in a documentation component for each version. And we’d have no easy way to compare, manage, and merge different instances of a document.
Branches handle all this for us. Creating a new branch is extremely cheap. You simply create a new branch from an existing reference in the repository, and the repository only stores what’s changed since that branch point.
To set the version of documentation stored in a particular branch, you simply specify the version in the component descriptor:
name: versioned-component version: '2.1' title: Versioned Component
This component descriptor communicates that the files taken from this branch contribute to version 2.1 of the versioned-component component. The name of the branch could be v2.1 or v2.1-beta. It doesn’t matter.
This is the only file you have to update when creating a new branch. All the page references for that component should be relative to the version, so you shouldn’t need to update any links. The next time you run Antora on the repository, you’ll see a new version in the component explorer drawer.
You may need to add the branch to your playbook file. Keep in mind that content sources are filtered by branch name, not by the version they contain. That’s because a single version can be spread out across multiple branches, or even multiple repositories.
It’s possible to have a versionless component. You’ll still use a branch, but you’ll only use one. In this case, put all the files in the master branch. Then, assign a version-agnostic name in the component descriptor, such as latest or stable:
name: versionless-component version: latest title: Versionless Component
You can also combine a versionless branch (like latest or stable) with version branches. They don’t even have to contain the same files.