When using a docker environment to build a pex, is there a way to treat the docker image as a dependency of the target so that it will build if not present?

Is this a docker image which is used by the docker env? Currently you can't use a custom image inside docker environment. You need to manually build and push the docker image that you want to use to some docker repo. https://github.com/pantsbuild/pants/issues/17714

We do use a custom image, though it needs a separate call to pants package. I guess we could avoid that by pushing to, eg. GHCR.