Basic branching terminology

First, though, note that the very word “version” is overloaded here. It can refer either to a completely separate branch of some module, or to a single specific instance or compose of a module. To keep terminology straight, we need to distinguish between:

  • A version branch: or more simply just a branch: a completely new, carefully planned version stream for a module. This might correspond to a major Fedora release, or a new Fedora SCL release. Creating a new branch should come with a new release target for the branch (or branches if we’re releasing multiple modules simultaneously.)

    A version branch may correspond to a new major version of the module, but there may be exceptions: for example, when we add specific features as a side-branch of an existing major version. The new branch may differ by SLA (eg. a faster moving Python) or by feature (eg. an “f-stream” branch giving early access to a specific new feature planned to be released in a subsequent update).

    Users must opt into a new version branch. By definition here, creating a new version branch must have no impact on users who have already enabled an existing branch of a module. If a user provisions a new environment and asks for the most recent version branch, then they may get the new version branch automatically; but no existing environments will transparently receive content for the new version branch.

  • A point-in-time version or instance representing a single compose of a module on a single version branch, built by and identifiable by the compose ID of the task used to compose the module within the build system.

    Such a point-in-time update may be just a scratch build, or may be internal-only and not released to the user. But once it is released, it forms a new update for that version branch of the module. Multiple released point-in-time updates therefore form an update stream over time for that branch.