[2.8.x] Switch to GitHub actions

[mkurz]

Very similar to #11142, just also includes tests against Scala 2.12.15 and sbt 1.3.13 (for scripted tests), but these are only activated for cron jobs. Actually I also diffed the original .travis.yml from the main and the 2.8.x branch to make sure I don't forget anything, but besides the additional Scala and sbt versions there was nothing.

Also includes backports of

• Introduce sbt-ci-release and add the publish GHA workflow #11249
• New sbt-header version with improvement #11248
• Replace scripts/local-pr-validation.sh with sbt validateCode in CONTRIBUTING #11250

[ihostage]

https://stackoverflow.com/questions/58798886/github-actions-schedule-operation-on-branch
Looks like we need something more smartly for cron task for 2.8.x branch 😄

[mkurz]

Yes I read this in the offical docs as well. We need to start the 2.8.x cron job from the default (main) branch 😢

[ihostage]

Should we have a duplicate of build workflow for 2.8.x? In main branch for schedule and in 2.8.x for PR's, right? 🤔

[mkurz]

I think yes, this is the only solution, to have duplicated workflow files in both branches.
I was thinking about other solutions, like define a workflow in the main branch that uses the GitHub api to trigger the workflow from the 2.8.x branch with curl, but that is also not possible:

• https://docs.github.com/en/actions/managing-workflow-runs/manually-running-a-workflow

...your workflow must be in the default branch....

• Also not possible via api: https://docs.github.com/en/rest/actions/workflows#create-a-workflow-dispatch-event - here the url is ...workflows/{workflow_id}/dispatches..., where the workflow id is just the name of the yaml file in the default branch (like https://github.com/playframework/playframework/actions/workflows/build-test.yml). The ref body param is just meta data I think, but does not select the branch from which to run the workflow.

There is even this action from the marketplace, but with the same limitations with the rest api (of course, its just a wrapper).

Also the repository_dispatch event can only be used to trigger workflows from the default branch.

I also was looking into composite actions, but I can not see how they help here.

Anyway.
There is a discussion going on already:
https://github.community/t/scheduled-builds-of-non-default-branch/16306
However since there is no offical "bug" yet, I created one 😛 :
community/community#16107

So I think we have to use duplicate files now... Let's hope they implement this feature soon.

[ihostage]

Nothing to say 🤷‍♂️ We will have to play by these rules for now 😞