Unable to set httpPort and tlsPort without a config file

[mitar]

I think it would be nice if more options could be set through command line arguments or through environment variables. In my case, I would like to set httpPort and tlsPort to regular values: with Docker image it is easy to do have them on regular ports. But doing that seems to be hard when running Pebble on GitLab CI as Docker runs as a separate Docker-in-Docker container, so it is hard to get a config file in there to bind mount it into the container to set a config file. The only way I found is that I do another Pebble image, extending official one, with my own config file and then use that one. A lot of work just to change two settings.

I have had great experience with Kong for CLI and config parsing in Go.