build.py: support buildkit-only environments #217
Description
In our Concourse CI/CD we only allow the command docker buildx build --push --tag ... because we don't expose dockerd over tcp to pipeline tasks. We do expose buildkitd over tcp which is a different protocol.
The current build.py from release 6.0.1 detects the mpr version, chooses between mono and dotnet, does docker pull and if it failed docker image build. Then it creates a container, copies the source code there, lets it run, and copies the mda back for extraction.
We would like to split the above into several pipeline tasks. Instead of building and running the mxbuild image the script build.py should create instructions what to build. Then our own task can check the presence of the mxbuild image in the repository and build and push it. Then another task would copy the artifacts into the image and let it create the mda.
Basically, the only part of build.py we need is the logic that generates the proper arguments for docker image build