Galaxy forces you to use their proprietary closed source Docker build and that’s possibly a problem for Reaction (although I’ve not confirmed that). We have our own base image because Reaction has specific build steps (like our plugin loader) that need to happen. I’m not 100% positive that’s your problem without signing up and testing it though.
If that is the problem, the only solution that I can think of to allow any base image is refactoring the Reaction build process to allow the use of any Docker base that supports generic Meteor apps. That’s not really in our plans at the moment, but I’d be happy to discuss a community contribution if that’s something you’re interested in working on. Feel free to discuss here in the forum if you’d like more info.
But yeah, you may also be right that it’s a memory issue. I have no idea what the defaults are for a single Galaxy container, but I suspect it’s not a lot. Perhaps try increasing the RAM. I’d definitely recommend 1.5-2gb RAM at the very least.
Also, if your app works when you build/run with our official base image, then I’d say you may want to contact Galaxy support to see if they might be able to help you debug further.