Before running the below steps, start the backend container. Once the backend service starts, note the url and provide that in the Dockerfile. Example:
ENV REACT_APP_API_URL 'http://127.0.0.1:5000/'
(currently this is the default)
docker build -f Dockerfile -t sim-client .
docker run -it -d --name simclient -p 3000:80 sim-client
http://localhost:3000/
(localhost can be replaced by the system IP where the container is running)
docker stop simclient