1. Docker container providing toolchain for c++ projects like XO
2. Container prepared using nix.dockerTools.buildLayeredImage.
   • doesn't contain unnecessary bulk
   • layers chosen automatically to promote sharing

$ cd ~/proj/docker-nix-cpp-builder  # directory containing this file
$ nix build

upload to docker

$ docker load <./result

To publish container to github, need a personal access token:

• on github.com/${myusername}:
  • visit profile (upper rhs or github.com)
    • developer settings (bottom of sidebar)
      • personal access tokens

        • tokens (classic) 'generate a personal access token'

          scopes needed:

          • read:packages
          • write:packages
          • delete:packages

$ export CR_PAT=${token}
$ echo $CR_PAT | docker login ghcr.io -u rconybea --password-stdin
Login Succeeded

tag image the way github expects, i.e. format ghcr.io/${username}/${imagename}:${tag}

$ docker image tag docker-cpp-builder:v1 ghcr.io/rconybea/docker-cpp-builder:v1

push to github container registry:

$ docker image push ghcr.io/rconybea/docker-nix-cpp-builder:v1
The push refers to repository [ghcr.io/rconybea/docker-cpp-builder]
...omitted...
v1: digest: sha256:e1aad3df64c1ea2ed6674b354e22e3807a831bb8229fa3be399c21f87ea72cb6 size: 6192

verify it's arrived by inspecting the gihub 'packages' tab [https://github.com/Rconybea?tab=packages]

image (github package) is initially private; make it public from the package's 'setting' link