PROM-0097: PromQL Metadata querying / promotion.

[roidelapluie]

This proposal was writting by hand. Grammar fixed by AI.

I asked AI 5 examples queries:

up{target[deployment.environment.name]="production"} == 0

up{target[team.name] as team} == 0

queue_depth{resource[deployment.environment.name]="production" as environment} > 1000

sum by (service) (
  rate(http_requests_total{resource[service.name] as service}[5m])
)

sum by (cost_center) (
  process_resident_memory_bytes{resource["billing/cost-center"] as cost_center}
)

[bwplotka]

So what are the keywords allowed here? resource namespace? What else?

[roidelapluie]

This proposal is agnostic of the keywords. The keywords are actual namespaces of metadata and should be defined in a broader metadata design doc like the ones that exist. I can think of resource for OTLP: resource, k8s, host, service...

[bwplotka]

Thanks. I am missing an exact definition of "namespace" or "scope", especially how it would be reflected in Prometheus world. Also if we expect UTF-8 in those (:

Maybe it's out of scope, but then how we could understand limitations of <prefix>[<suffix>] syntax?

If we mean here OTel entity namespaces and let's take process.executable)

Then should I go for

cpu_info{process["executable.name"]="docker" as exec}
or
cpu_info{"process.executable"[name]="docker" as exec}

..and if this "namespacing" is required, why not cpu_info{["process.executable.name"]="docker" as exec}

Then can we guarentee some namespace is always there for metadata?

[roidelapluie]

I believe we can have better and will do a second proposal later.

[roidelapluie]

Closing in favour of #99