config: read from a YAML file

[adamdecaf]

Customers Version: v0.6.0-dev

What were you trying to do?
Instead of reading dozens of env variables we should have one YAML file that has all of our options changed from their defaults. This follows how all other services are configured.

[alovak]

Adam, I think that it would be better if we keep both ways to configure our application. Reading config variables from environment makes it super easy to run service in docker. Especially when want to cross-link services using their names.

base/config reads config from file. I'll use it for Customers but will add ability to use env variables for some configuration parameters.

What do you think?

[adamdecaf]

env variables are pretty messy and annoying to configure at scale. I wish I had never used them to configure services. Customers is currently the only service of ours that uses env variables for configuration.

We include an example config in other projects that folks can configure. That config file can be volume mounted in docker-compose setups as well, which doesn't require an image rebuild.

Also, I'd really like us to focus on releasing v0.5.0 of Customers which will already contain tons of changes for the larger community before working on this issue. We should have some examples, docs, updated CHANGELOG, and announcements in the public slack about what/why we've changed so much. It'll come as a shock to anyone using v0.4.1.