what about the order of labels? "a=x,b=y" != "b=y,a=x"

Thanks for your feedback! For the sake of correctness, we should do it. I think we can handle this case by first sorting the array

Solved at be7612d

ok, so the code may be technically correct now, but isn't it your code that creates metrics family with labels in the first place? Is it possible to have more than one label? If not, do you need to concatenate them into a string rather than just looking up the service name?

Also, why are only service names used as labels, isn't there a use case where operation is also a label?

Hi @yurishkuro, Yes Jaeger control the label inside to_domain.go, this is what I have been thinking about in the first place, we do not actually need to sort it because it's always the same order (but for safety, this is good and it's not that computationally expensive (just several labels is fast)). Yes, it's possible to have more than one label (e.g service_name, operation). Because there are more than one label, we can't look up by just the service_name.

No not only service_name is used as label, operation is also used as a label, check this:

// toDomainLabels converts the bucket key to Jaeger metric labels.
func toDomainLabels(key string) []*metrics.Label {
	return []*metrics.Label{
		{
			Name:  "operation",
			Value: key,
		},
	}
}

don't you need to generate a NaN data point?

I think that this is very important, that the e2e tests need to verify the labels, without it we may fail the e2e test

Hi @yurishkuro, this is solved at #7303