This is #5 (closed) (which saves us about a whooping GB) followed by more actions: reducing the layers and being more careful with
Here's the result I get:
~/heptapod/docker $ docker image list octobus/heptapod | head -3 REPOSITORY TAG IMAGE ID CREATED SIZE octobus/heptapod testing 5c4d9aadd23b 15 minutes ago 2.02GB octobus/heptapod 0-12-testing 387afcb08a8a 47 hours ago 3.11GB
An interesting metric is the comparison with GitLab base image:
~/heptapod/docker $ docker image list gitlab/gitlab-ce | head -3 REPOSITORY TAG IMAGE ID CREATED SIZE gitlab/gitlab-ce 12.2.12-ce.0 1fe894d81d4f 4 months ago 1.76GB gitlab/gitlab-ce 12.3.5-ce.0 7783a0d67474 6 months ago 1.77GB
These don't change in the lifetime of a Heptapod version, from 0.x.0rc1 to 0.x.y.
In particular, retrieving a freshly built image with my lousy DSL line now completes in less than 2 minutes, given that the GitLab base image is already present.