This repo contains a github actions workflow file; which when configured will help you achieve CI.
The workflow does docker login for you to push to your docker registry, so it expects 2 secrets to be added to your repository.
username: docker registry usernamepassword: docker registry password
The default registry server it pushes to is https://index.docker.io/v1/ if you want to push to a different registry, add login-server: <your-login-server> to the docker login step.