Refactor the workflows so that we can use build-push-action also for
publishing. This is a precondition for switching to buildx, needed for
multi-arch images.
The trick needed for this is using an environment variable to control
whether we should push when building the master branch, initializing it
according to the tag status.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Add the github/ghcr equivalent to travis/dockerhub. With this in place,
we can also deploy the next and latest images to ghcr. Adjust
Dockerfile.isar accordingly. Also update the badge shown in the README.
We model the workflow with github a bit differently than so far: next
and master branch are different workflows. The former includes testing,
the latter just updates the container image. This is based on the
(offline) workflow to push changes to next first and have no commits
in master that haven't been in next before, except for release commits.
The master workflow also triggers on tags in which case it additionally
tags the container images accordingly and pushed that as well.
Travis is removed in the same run to avoid pushing differently built
images to the different registries.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
