fix: `.` is removed in nodeName

[CatherineF-dev]

What this PR does / why we need it:

How does this change affect the cardinality of KSM: (increases, decreases or does not change cardinality) No

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes # an issue raised in slack chat We see the fieldSelector get created with the node-name … but it’s missing the .

[diranged]

This should fix https://github.com/kubernetes/kube-state-metrics/issues/2374. Thank you, I hope this can get merged quickly!

[logicalhan]

/assign @dgrisonnet /triage accepted

[mrueg]

There was a conversation here: https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1356982673 https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1357024577

Do we still need this to differentiate between "" and nil?

[CatherineF-dev]

Good point. Updated to only add \\.

Tested: https://go.dev/play/p/K5GtruNWjO0

[mrueg]

https://kubernetes.io/docs/concepts/overview/working-with-objects/names/#dns-subdomain-names

We can reuse https://github.com/kubernetes/apimachinery/blob/0ee3e6150890f56b226a3fe5a95ba33b1b2bf7c7/pkg/util/validation/validation.go#L177 probably.

To be exact: IsDNS1123Label https://github.com/kubernetes/apimachinery/blob/0ee3e6150890f56b226a3fe5a95ba33b1b2bf7c7/pkg/util/validation/validation.go#L187 function?

[CatherineF-dev]

There was a conversation here: https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1356982673 https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1357024577

Do we still need this to differentiate between "" and nil?

I read https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1356982673 https://github.com/kubernetes/kube-state-metrics/pull/2217/files#r1357024577 again and find it is not related to differentiate between "" and nil.

[CatherineF-dev]

Updated. Need review again.

[dgrisonnet]

I don't get why we have this NodeType structure from https://github.com/kubernetes/kube-state-metrics/pull/2217/. Pods in scheduling state could be handled separately, even maybe with a dedicated CLI option. I think that the code could be simplified.

Also one thing I am curious about is what would happen once the pod is scheduled on the node. Do we continue to produce a stale metrics with the state of the pod when it wasn't schedule? Or do we have a mechanism to check that this pod shouldn't be watched by this shard anymore?

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[CatherineF-dev]

Do we continue to produce a stale metrics with the state of the pod when it wasn't schedule?

No. I tested for both daemonset (watch scheduled pods) and deployment (watch not scheduled pods).

# Test for the deployment

# 1. deploy a pod
kubectl apply -f https://raw.githubusercontent.com/CatherineF-dev/k8s-hello-world/main/unschedule_pod.yaml

kubectl get pods --field-selector spec.nodeName= -A
NAMESPACE   NAME                          READY   STATUS    RESTARTS   AGE
default     hello-node-7d78fd84d9-rqbjh   0/1     Pending   0          38s

# 2. can see metrics when this pod is not scheduled

curl localhost:8080/metrics | grep hello-node | grep schedule

kube_pod_status_scheduled{namespace="default",pod="hello-node-7d78fd84d9-7grpc",uid="1c9982aa-e99b-46a0-97c0-b03bf1b94b47",condition="true"} 0
kube_pod_status_scheduled{namespace="default",pod="hello-node-7d78fd84d9-7grpc",uid="1c9982aa-e99b-46a0-97c0-b03bf1b94b47",condition="false"} 1
kube_pod_status_scheduled{namespace="default",pod="hello-node-7d78fd84d9-7grpc",uid="1c9982aa-e99b-46a0-97c0-b03bf1b94b47",condition="unknown"} 0
kube_pod_scheduler{namespace="default",pod="hello-node-7d78fd84d9-7grpc",uid="1c9982aa-e99b-46a0-97c0-b03bf1b94b47",name="default-scheduler"} 1

# 3. can't see metrics when this pod is scheduled 
curl localhost:8080/metrics | grep hello-node | grep schedule

[CatherineF-dev]

@dgrisonnet need review again.

[mrueg]

Closing this in favor of https://github.com/kubernetes/kube-state-metrics/pull/2388

Feel free to reopoen if anything changes.