`${DOCKER_REGISTRY}` is just an environment variable set for my docker hub username. The reason this was done is because it’s looking at (in my case) `kritner/kritnerWebsite` — without that environment variable there it’s tied to my specific accounts docker image. It’s probably more confusing that it’s there, but my intention was you could swap in your own dockerhub username in that environment variable to have it use your own image (not necessarily with my website, but just as a generality)