CODEWITHSUNDEEP
promqlprometheus-operator
Shubham Choudhary
Shubham Choudhary

Reputation: 135

What's label:metric:function in PromqQL?

I am reading kube-prometheus, https://github.com/coreos/kube-prometheus and came across a PromQL in a Prometheus rule file which I am having hard time understanding.

sum(namespace:kube_pod_container_resource_requests_cpu_cores:sum)

in here https://github.com/coreos/kube-prometheus/blob/master/manifests/prometheus-rules.yaml#L673

But similarly this 

sum(container:kube_pod_container_resource_requests_cpu_cores:sum)

doesn't return anything where 'container' is just a label like 'namespace'

This is how the instant vector looks like for "kube_pod_container_resource_requests_cpu_cores"

kube_pod_container_resource_requests_cpu_cores{container="kube-controller-manager",instance="172.17.0.7:8080",job="kube-state-metrics",namespace="kube-system",node="minikube",pod="kube-controller-manager-minikube"}

Can someone explain to me how's this working and were in the PromQL documentation it's mentioned to do this kind of query?

Can we do a query like this "label:metric:function"?

Thanks

Upvotes: 1

Views: 450

Answers (1)

Kamol Hasan
Kamol Hasan

Reputation: 13516

You cannot query like, "label:metric:function".

namespace:kube_pod_container_resource_requests_cpu_cores:sum is nothing but a name of a Prometheus rule which is define in here.

    - expr: |
        sum by (namespace) (
            sum by (namespace, pod) (
                max by (namespace, pod, container) (
                    kube_pod_container_resource_requests_memory_bytes{job="kube-state-metrics"}
                ) * on(namespace, pod) group_left() max by (namespace, pod) (
                    kube_pod_status_phase{phase=~"Pending|Running"} == 1
                )
            )
        )
      record: namespace:kube_pod_container_resource_requests_memory_bytes:sum

So, whenever you create a new rule, Prometheus creates a new time series metric named after the rule name (i.e. namespace:kube_pod_container_resource_requests_memory_bytes:sum).

If you want to query something like container:kube_pod_container_resource_requests_cpu_cores:sum, you need to record a rule first by this name.

NB:

Recording rules should be of the general form level:metric:operations. level represents the aggregation level and labels of the rule output. metric is the metric name and should be unchanged other than stripping _total off counters when using rate() or irate(). operations is a list of operations that were applied to the metric, newest operation first.

Upvotes: 3

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