This setup-only mode will setup a docker builder with the stickydisk
mounted but will not run a Docker build. The use case here is to allow
customers to then run their custom Tilt files or Docker commands against
our builder. The other subtle change is that we only cleanup in the post
step of this builder action. It is still to be seen if you can start several
of these builders at the same time in a workflow but we can do that as a follow
on.
This change teaches the build push action to request a stickydisk
every time it runs. Once the SD is hotloaded the VM will mount
the buildkit root dir and starts buildkitd.
1. Checks we have buildx installed
2. Configures a remote builder if we get an address back
3. Uses the already configured builder if we don't get an address back
This change does not plumb the dockerfile path through as the entity,
and does not differentiate a failed build from a succesful to report
to anvil in the post step yet.
