Remove Guice + use Singleton to fix initilization potential deadlock

[Dohbedoh]

Fixes #635 . Second attempt...
Removed Guice.
Using a Singleton with a simple constructor.
Collectors get register with the Jenkins initialization milestones.
Job related collectors later on when jobs are loaded.

Note that the AsyncPeriodicWork would kick off later on after JOB_CONFIG_ADAPTED https://github.com/jenkinsci/jenkins/blob/jenkins-2.468/core/src/main/java/hudson/model/PeriodicWork.java#L104.

Changes proposed

• Prevent deadlock on initialization of DefaultPrometheusMetrics
• Remove Guice injection

Checklist

• Includes tests covering the new functionality?
• Ready for review
• Follows CONTRIBUTING rules

Notify

@Waschndolos

[Waschndolos]

Thank you for the PR! I'll test it in the next couple of days and come back to you

[Waschndolos]

The code looks good. I've installed a version of this PR in our Test instance. No issues so far (but didn't have any in the previous attempt, since I'm using a dockered controller). I'll check the instance further and do another test on a non dockered environment. If that's ok as well we might give it a new try :)

[Dohbedoh]

Sounds good. Thanks @Waschndolos !

[Waschndolos]

@Dohbedoh. Sorry for the delay, my computer died, had to reinstall 👍 I've installed Jenkins on my unix based system without docker and it doesn't show any error, as well as prometheus endpoint is still working. So I think we're good to go. I'll double check the logs in the companies jenkins tomorrow and if they're ok I'll merge it. Thanks again for the fix!

[Waschndolos]

Released with 778.ve1c932a_ff24f