Copied from https://github.com/metaneutrons/docker-simpleproxy with the entrypoint.sh modified to support running multiple proxies.

Build the container

docker build -t simpleproxy .

Run multi proxies

docker run -d -p 6200:6200 -p 6201:6201 -it simpleproxy '-L 6200 -R 192.168.1.1:6200|-L 6201 -R 192.168.1.1:6201'

Use the | to separate multiple simpleproxy commands.