For me the problem is that yaml (and the compose specificatio n) is not self sufficient to support complex scenarios. You will start by setting things and discovering that ENV vars * on the global scope of the compose specification are not supported so you end up having to template and output yaml.

Try having 40 microservices and quickly iterate between fixing bugs in them. Some you want mounted, others you want running unmounted. I understand the premise is already broken, you do not want 40 microservices, but that's not a precondition you can fix without a time machine.

[[* EDIT: by env vars on the global scope, I mean setting things on the global scope by using an env var, say, you want a certain volume named after an environment variable. You can only use ENVs as values.

    # this works
    foo: "${SOME_ENV}"
    # this does not
    ${SOME_ENV}: "foobar"