feat(loki/src/k8s): configurable default instance label for scraped pod logs

[hainenber]

PR Description

Which issue(s) this PR fixes

Fixes grafana/alloy#211

Notes to the Reviewer

PR Checklist

• CHANGELOG.md updated
• Documentation added
• Tests updated
• Config converters updated

[clayton-cornell]

Some doc input/comments

[clayton-cornell]

Over to @grafana/grafana-agent-maintainers for a code review.

[clayton-cornell]

Approved from a docs standpoint

[mattdurham]

Why do we need a separate enabled value? Would having a value inherently make it true?

[hainenber]

Would an empty string indicate of no default instance label for every podlogs or having an empty default instance label?

I'm not sure if having a separate value is the way to go here but I feel like its explicitness would help.

[tpaschalis]

AFAIK in both Prometheus and Loki, an empty value label is considered equivalent to a label that doesn't exist.

So in this case, you wouldn't really be able to have an empty instance label. I'd agree this makes sense as an attribute instead of a block. It should only override defaultInstance when it's expliticly supplied as a non-empty string.

[hainenber]

Very cool knowing the practice put in place by other parts of the ecosystem :D

I'd try implementing it that way.

[hainenber]

I just realized that the original requester would like to disable the behavior of setting default instance label too 🤦

And having an empty string to disable the behavior would be breaking change, unless we choose a token to signify the act of disabling, like defaultInstanceLabel="disabled" or something, which doesn't seem right to me 🤔

To have both the ability to disable the behavior and to set a custom default instance label, I think we gotta resort to block now (unless having a separate attribute :D)

[github-actions]

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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!

[thampiotr]

Closing as the linked issue is closed too.