We are all well aware of the tried and true method of setting your applications variables using ENV, right? Stuff like ENV[‘AWS_KEY’], etc. is a very common way of doing things.
However, there might come a time when it’s either not possible to set those variables, or the whatever. In that case, we can use a YAML file to load them. In this example, we load a YAML file with the variables, and then override them with ENV variables if those have been set. This is a great way to provide a default method, and then have a custom override.