The problem

Before you put a new nginx config in production, you try the image nginx:1.27 on your laptop. You run it as a container named web, with port 80 of the container published on port 8080 of your machine, so curl http://localhost:8080 reaches it.

The reps follow web from docker run to docker rm. You also run alpine:3.20 once to print the file /etc/alpine-release, which holds the Alpine version. You pulled both images earlier.