Welcome, @russellwstanley. There has been lots of discussion of people who want to be able to have a docker_compose file that solves all their problems, but it’s not quite that simple. There has been much discussion about this (that I can’t find in 30 seconds).
To see what settings you can pass to the container you can look at discourse/config/discourse.config.sample at main · discourse/discourse · GitHub and discourse/config/site_settings.yml at main · discourse/discourse · GitHub to see what can be configured with environment variables.
But some things need to be done with things like
rake db:migrate
rake assets:precompile
so even if you get an image that has all the right stuff, it’s not quite as simple as just cranking it up.