Update a check run from 'outside' a Github App?

My Github App triggers a remote and long-running CI task. When the CI task completes I need of course to update the check run with the CI result status. However, I’d like to do this from the CI task itself. Since the CI task is not part of the ‘App’  the Github Checks API is not available to me, AFAI. Might there might be some way of(securely) passing credentials between the App and the CI system, if that’s what it would take, to permit the CI to update the check run?

The background to this is I want to do my CI outside the App and Github but  also want to support post-CI options (e.g rebuild) from the Github Checks UI. ( I can’t, for various reasons, include a public url directly into the CI).

GitHub doesn’t provide a way to securely transfer credentials to some outside service, no. That would be the part that you would have to design and implement. On the other hand, the GitHub Checks API is available to anyone with the appropriate credentials and authorization, whether that is an app or a user. So if you managed to supply the appropriate credentials that have the right authorization to your external CI task, it could update the status.

I hope that helps!