docker compose: config.yml is a folder

[campoy]

Due to the way config.yml is mounted into to Docker, when the file doesn't exist in the current directory it is mounted as an empty directory.

This leads to the following error message:

lookout_1   | Can't open configuration file: read config.yml: is a directory

I propose solving this by either:

• providing an empty config.yml, or
• changing the code to ignore config.yml if it's not a file.

[carlosms]

The error message could be improved to be more user-friendly, but having a default working config.yml is unfortunately not possible. Not all the config options can be set with an env var, and some are required to work.

You need to set at least the analyzers, otherwise we won't produce any comments.
And also the repos to watch are set in there. For user & token you also need repositories. And for github app auth, app_id and private_key.

[campoy]

I think the problem is that when the file doesn't exist it ends up being created as a directory.
Is there any way to avoid that behavior?

I'd rather have an error saying something like "no analyzers found in config.yml" than this

[carlosms]

I couldn't find a way to detect the file before launching the containers, so in #320 I've added a better error message for this specific scenario.