github-discovery should only output repositories with relevant files

[nirga]

Currently the way github-discovery is implemented is that it outputs all repositories that match a certain pattern, and leave it to a lower level to find the relevant catalog file within that repo. This causes a weird behavior if for example the following pattern is given:

locations:
    - type: github-discovery
      target: https://github.com/backstage/*mkdocs/blob/master/catalog.yaml

And only some of the repos with mkdocs in their name contain a catalog.yaml file. All repos will be outputted, which will cause an error to be thrown for those repos where catalog.yaml file doesn't exist.

Expected Behavior

Only relevant repos matching the entire filepattern should be outputted.

Current Behavior

Errors are thrown when reading repositories that partially match the file pattern.

Possible Solution

Steps to Reproduce

Context

Your Environment

• NodeJS Version (v12):
• Operating System and Version (e.g. Ubuntu 14.04):
• Browser Information:

[freben]

Hm i wonder if we should really mix the repo and file concerns. It would make sense to emit the locations with presence: 'optional' instead. That makes it so that the next iteration doesn't strictly require that something actually exists on the given path.

[nirga]

I like that! I didn't like mixing the concerns as well. Creating a PR.