Publish images to ghcr.io

[j-mueller]

Publish the two images to GHCR.

• When the workflow is triggered from a pull request: Use pr-${pull_request_number} as the tag of the image
• When the workflow is triggered from a git tag: Use ${version} as the tag of the image

The PR-specific builds should make it easier to try out in-progress changes locally if the full toolchain is not available.

[j-mueller]

We should apply some distributive law to nix-build the images first and then parallelise the workflow by image. Currently we start a separate workflow for each image, which consumes a lot more compute-minutes.

[j-mueller]

Test with

docker run --rm --publish 8080:8080 ghcr.io/input-output-hk/wst-poc-mock-server:pr-58 (or podman equivalent)

curl -v localhost:8080/api/v1/healthcheck should then return code 200

[choener]

We should apply some distributive law to nix-build the images first and then parallelise the workflow by image. Currently we start a separate workflow for each image, which consumes a lot more compute-minutes.

I have some preliminary work in .github.com/workflows/ci-nix.yaml.
But cache restore is problematic:

• I will have to prune the nix cache and only store those store paths that are locally built (github limitations on space)
• Then restore correctly
  Alternatively, cachix could be used ...

[choener]

Tried and works for me.
Have left comment on missing hashing.