Add Github Actions workflow that pushes a new Docker image to Github Docker Registry

[martin-g]

The current version of the Github Action workflow would push a new Docker image on every push to the master branch.
The images will be pull-able from https://github.com/popgenmethods/smcpp/pkgs/container/smcpp

AMD64 and ARM64 Docker images from my testing could be seen at https://github.com/martin-g/smcpp/pkgs/container/smcpp

If you prefer to push to https://hub.docker.com see https://github.com/docker/login-action#docker-hub, but for this you will need to setup Github secrets with the credentials.

[martin-g]

Any feedback on the proposed changes ?

[terhorst]

Hi Martin,

Apologies for the delay, and thanks for all you hard work on this! Everything looks good. As luck would have it, work is buying me a new ARM-based Mac, so I will soon have the ability to test out the new images. As soon as I get that done I will merge your PR. Thanks again!

[martin-g]

Awesome!
Thank you, @terhorst !

[martin-g]

Thanks for merging it, @terhorst !

It seems you will have to change the visibility of the new Docker image to public manually.
https://github.com/orgs/popgenmethods/packages is empty for me!
But https://github.com/popgenmethods/smcpp/actions/runs/3323388223/jobs/5493663203 is successful!

$ docker pull ghcr.io/popgenmethods/smcpp:221025-1834
Error response from daemon: Head "https://ghcr.io/v2/popgenmethods/smcpp/manifests/221025-1834": denied: denied

It seems the Docker image is there but private.

Please go to https://github.com/orgs/popgenmethods/packages/container/smcpp/settings, scroll to the bottom (the Danger Zone) and change the visibility to Public.
This is a one time operation for each new Docker image.
Thanks in advance!