Mini rack app in an HTTP webserver to test load balancers - GET / requests return "Hello from hostname". By default puma runs on port 9292 and it can be configured to listen on whatever port you'd like by passing a -p parameter when running the container.
docker run -p 3000:9292 ghcr.io/naft-a/rack-hello-host:latest bundle exec puma -C puma.rb