[erlang-questions] Dealing with different environment configurations?

[Roger Lipscombe]

We're currently packaging our Erlang node with relx. This generates a
startup script that assumes releases/1/sys.config exists.

Now, we have to deal with a couple of different environments: dev,
test, staging, production. "production" is further divided into (e.g.)
"production-us-east", "production-us-west", "production-eu", etc.

How do people deal with the need to have different configuration files
in different environments? Do you build a different release for each
environment? Or do you replace the sys.config in each environment? If
so, how?

Thanks,
Roger.