Refactor Docker build and automatically push images

[joschi]

This change set does two distinct things:

• Refactor the Docker build to use a proper build stage so that development dependencies aren't shipped with the final image.
• Create a GitHub Actions workflow to automatically create and push Docker images of Fredy (latest and tagged releases) to the GitHub container registry.

As a result, the Docker image is ~200 MiB smaller than before:

orangecoding/fredy          latest               5f93286a4e15   4 minutes ago    514MB
ghcr.io/joschi/fredy        pr-2                 3493253bc074   11 minutes ago   311MB

Demo repository: https://github.com/joschi/fredy/pkgs/container/fredy

Demo output from https://github.com/joschi/fredy/pull/2: logs_2.zip

References:

• https://docs.github.com/en/actions/publishing-packages/publishing-docker-images#publishing-images-to-github-packages
• https://github.com/marketplace/actions/docker-login
• https://github.com/marketplace/actions/docker-metadata-action
• https://github.com/marketplace/actions/build-and-push-docker-images

[orangecoding]

Looks awesome. Thanks!

[orangecoding]

@joschi quick question, there's a docker section in the readme. I assume this has to be changed as well no?

[joschi]

@orangecoding All of these commands are still working: https://github.com/orangecoding/fredy/blob/2764b2b77651a43e2653ae5c06a7e09ed13c9303/README.md#L84-L97

The only thing we could add is the availability of the automatically built Docker image in the GitHub container registry: https://github.com/orangecoding/fredy/pkgs/container/fredy