Add pre-release support

[jenstroeger]

Currently

The release workflows support only final releases of a package, and no pre-releases. The branches support these release workflows by PR → staging branch → main branch, where a push to the main branch triggers building and publishing a final package release.

Proposal

We want to add support for building and publishing pre-releases of the package. To achieve that we can add the following workflows to the staging branch that trigger on push event:

1. If the commit log shows a release will be build (i.e. there’s at least one fix: or feat: or breaking change) then
   1. Build all release artifacts; then
   2. Bump the package’s version using commitizen’s --prerelease option, e.g. using rc for release candidates, and push the new tag; then
   3. Create a pre-release on Github and attach the pre-release build artifacts.

We can probably refactor the current release.yaml into two workflows:

1. release-rc.yaml that triggers on push to the staging branch and produces a pre-release; and
2. release.yaml that (much like its current incarnation) triggers on push to the main branch and produces a final release,

both of which can make use of two new reusable workflows that

• Build and bump a branch; and
• Create a Github release and publish the artifacts.

For this to work, we also need the following two features available:

• fix: properly bump versions between prereleases commitizen-tools/commitizen#799
• feat: preserve prerelease linearity commitizen-tools/commitizen#800

[jenstroeger]

After some tinkering with cz I think this feature needs to wait:

• the Conventional Commits specification doesn’t actually state how to bump pre-releases, see issue Add support for pre-release versions conventional-commits/conventionalcommits.org#398 (and this comment); and
• commitizen doesn’t bump correctly (what is “correct” without spec, though), see issue Bump increments to new pre-release version from pre-release version when it wouldn't from final version commitizen-tools/commitizen#688.

For reference, there’s also an interesting Discussion: pre-release versioning and PEP440 cross-compatibility.

[jenstroeger]

And just out: v1.6.0 of the SLSA Generator added support for pre-releases as well 👍🏼

[behnazh]

I think this would make sense if apart from the main and staging branches, there are additional ones for pre-releases.

[jenstroeger]

Commitizen v3.14.0 add support for pre-release bumps.

[jenstroeger]

@behnazh given the failing run here I think a pre-release would have caught this, instead of failing the actual final release.