Omnibus makes a ton of assumptions about how many things you want bundled, as well as the monolithic configuration is daunting. I'd suggest breaking up into smaller containers for each service. No matter what container medium you choose, the philosophy of omnibus isn't something you want to 'containerize' as it is.
We run gitlab and the full config is 57 lines. A little more than half of those are comments or blank lines. This includes email and oauth. I would suggest not unbundling.
