Setup Github actions to automate building and pushing of images

[giohappy]

Multiple workflows will be setup to automate the build and push of each Docker image contained in this repository:

• Geoserver
• Nginx
• PostGIS
• Letsencrypt
• Geoserver data dir conf

The "Build and push Docker images" Github Action will be adopted and configured appropriately.

I've tested a simple example for Geoserver here

We will need to setup a Docker "service" account for the GeoNode organization. Its credentials will be used to push the images.

[matmair]

hi @giohappy are you aware of GitHubs built-in docker registry? Publishing to it is very simple and you get a very well integrated experience. If you are intrested I would be happy to provide a PR to build one of the images.

[giohappy]

hi @matmair. Yes, using the built-in registry would be nice, but we still need to use Docker Hub since the existing projects are configured to use that.

We could start pushing the images on both sides and start transitioning new GeoNode projects to the ghcr.io registry.

A PR is always well accepted, but it must grant the current workflow will keep working.