Fyi - I’ve set up a way for myself to build a Discourse image on a devbox and deploy that to a server in a way that eliminates the requirement to use the launcher script.
More discussion about that here in a pull request I created.
I set this up in a way that makes it fully compatible with Discourse’s official docker setup, so you don’t have to worry about this solution going out-of-support or breaking.
The TLDR on how this works is I made the Docker image responsible for executing bootstrap commands upon startup (instead of the launcher script).