Both your solution, Bazel, and that of the neighboring comment, Gitlab, involve way too many parts you don't necessarily want or need. I'm not going to rewrite my build process (which is generally a thankless job with very low customer ROI) just to build container images :-)
Same story for Gitlab, nobody's going to migrate from Github or Bitbucket just to get container images builds.
Same story for Gitlab, nobody's going to migrate from Github or Bitbucket just to get container images builds.