container_image full docker image tarball

Question

As mentioned here, the full docker image tarball is created as an implicit output on demand.
But, what does it mean by on demand? how can I inform the build to produce it?
Seems a lack of documentation here.

Answer 1

You can specify the "image.tar" target name explicitly to build it; for instance, if your container_image target is named my_image in //foo, this will produce the tar archive in bazel-out:

bazel run //foo:my_image.tar