fix(loki/src/k8s_events): correctly update health state for the component during operation

[hainenber]

PR Description

Which issue(s) this PR fixes

Fixes grafana/alloy#274

Notes to the Reviewer

PR Checklist

• CHANGELOG.md updated

[tpaschalis]

I don't think this solves the issue in #6181 entirely.

ApplyTasks will return an error if the runner is closed, or if the context is already cancelled/exceeded via ctx.Err; we don't have a way to propagate errors directly from the underlying tasks as the worker interface is Run(ctx context.Context).

To make this happen we'd need to have a goroutine-safe mechanism of bubbling up the errors and sieving through them.

[hainenber]

Ok so my approach is to change the worker interface as there aren't many implementations yet.

The ApplyTask function will now collect returned errors and store within the caller's struct.
 
I add a new method for Worker interface to get the bubbled-up errors, GetWorkerErrors to help setting the component's health properly.

PTAL if you have any concern re: goroutine-safe aspect. Thanks!

[hainenber]

I've changed my approach and now choose one with smaller blast radius. That is, the eventController retain any error when executing Run method and there's a recurring actor in the component to set health based on the returned results.

Not exactly ideal since the component's health is not reflected right away but I think it's a worthwhile tradeoff

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[github-actions]

This PR has not had any activity in the past 30 days, so the needs-attention label has been added to it.
If you do not have enough time to follow up on this PR or you think it's no longer relevant, consider closing it.
The needs-attention label signals to maintainers that something has fallen through the cracks. No action is needed by you; your PR will be kept open and you do not have to respond to this comment. The label will be removed the next time this job runs if there is new activity.
Thank you for your contributions!