Comment 1 for bug 1996058

I can't tell you what it would take for bzr branches, but you could have a look at how this works for git - it all starts with an event created when a ref is updated:
https://git.launchpad.net/launchpad/tree/lib/lp/code/subscribers/git.py

Having a look at https://git.launchpad.net/launchpad/tree/lib/lp/code/model/cibuild.py we do not abstract the vcs, but that should be doable.

We def. need to go down the stack through launchpad-buildd and lpcraft(the CI runner). launchpad-buildd's https://git.launchpad.net/launchpad-buildd/tree/lpbuildd/ci.py is designed to work with git only - but probably also could be refactored and extended.

lpcraft ( https://lpcraft.readthedocs.io/en/latest/ ) should be vcs agnostic if I remember correctly.

So this seems to be doable, with quite some effort, and especially some coordinated one (align launchpad and launchpad-buildd changes).

The most important thing would be whether this is something we want to have and maintain in the long term. That is something we need to discuss with the team, especially with Colin and probably our "manager". Colin is off for probably another week. I will discuss this once he's back.