config() returns nil when resolving configuration fails

[indrekj]

The comment https://github.com/Nebo15/confex/blob/master/lib/confex.ex#L314 says that ArgumentError is raised when configuration cannot be resolved. This however is not true.

Here you can see the configuration:

iex(1)> {:ok, c} = Application.fetch_env(:transporter, Transporter.ProxyRequests.Process)
{:ok,
 [
   bypass: %{
     ~r/\/\/client-logger\..*/ => %{
       host: {:system, "CLIENT_LOGGER_SERVICE_HOST"},
       port: 80,
       scheme: "http"
     }
   }
 ]}

CLIENT_LOGGER_SERVICE_HOST env var is not actually set.

If I use use Confex, otp_app: :transporter macro, then Transporter.ProxyRequests.Process.config() returns just nil.

I think this is because Confex is using get_env https://github.com/Nebo15/confex/blob/master/lib/confex.ex#L319 which defaults to nil on error.

Feel free to close this ticket if this behavior is expected. It caused us a small incident because one of the env vars was missing and it didn't fail fast.