add mimir ruler mixin dashboard

[QuantumEnigmaa]

Towards giantswarm/roadmap#3162

This PR adds the mixin dashboard for mimir-ruler.

Checklist

• Update changelog in CHANGELOG.md in an end-user friendly language.

[QuantumEnigmaa]

Most of the graphs are not working :

[QuentinBisson]

Did we enable the ruler's service monitor?

[QuantumEnigmaa]

Did we enable the ruler's service monitor?

Well, the mimir-ruler SM is present on the cluster

[QuentinBisson]

Do we have the ruler recording rules? SOrry I've been playing with alerts all day, my brain is fried like chicken

[QuantumEnigmaa]

Do we have the ruler recording rules?

Yes, the ruler is working fine :

ts=2024-03-04T15:10:35.364014431Z caller=ruler.go:564 level=info msg="syncing rules" reason=periodic

The issue here is coming from the queries used in the graphs. Those are not even recording rules, but they're the weird cortex prefixed queries that mimir is using for all of its mixins (for example : cortex_prometheus_rule_evaluations_total here)
As I mentioned earlier I'm really troubled with those queries because I don't get where they're coming from. I'm gonna ask in the grafana slack

[QuentinBisson]

Makes sense to Ask upstream. It's possible the mixins are not UP to date with the exposed metrics

[QuantumEnigmaa]

Magic happened after golem upgrade :

Only 2 graphs are still missing some data :

However I have some concerns about the datasource. Those screenshots were taken with the default datasource (i.e prometheus). But whenever I switch it to mimir we don't have the same graphs :

[QuantumEnigmaa]

Considering the graphs with no data displayed, this is due to the fact that there is actually no data. For example, the Queue length panel is acutally working :

But since the graph is supposed to show queues longer than 0 and there are none during the time period selected, then no data is displayed.
Moreover, since there are no Missed iterations neither, obviously no data is displayed.

So in my opinion, all good here (except for the difference I mentioned between the prometheus and mimir datasource)