How to get resource usage of different (fake) nodes

[annis-souames]

Hello,

I have a project where I'm tasked to build a custom scheduler, this scheduler will use real-time information about CPU and RAM usage of each node in the cluster. I'm using Kwok in order to simulate the cluster and create a large number of nodes.

I created a fake cluster with 8 fake nodes with different CPU and RAM capacities, when I run kubectl top nodes it tells me that the Metrics API is not available. Is there any way I can get the current CPU/RAM usage of those fake nodes ?

To better explain this, imagine we have a node with 6 cores and 16GB of RAM, and we deploy a fake pod that requests 2 CPU and 4GB of RAM, and another pod with 1 CPU and 2GB of RAM, then the current usage of the node would 3 CPU cores and 6GB of RAM.

Is there any way to get these metrics directly without having to loop through the definitions of the YAML pod and running the calculation.

kwok version: v0.5.1 go1.21.7

Thank you

[wzshiming]

Lucky for you, the docs in #975 #1004 have just been advanced, but are still incomplete.

https://kwok.sigs.k8s.io/docs/user/metrics-configuration/
https://kwok.sigs.k8s.io/docs/user/resource-usage-configuration/

[annis-souames]

That's great ! thank you @wzshiming, I tried it as mentioned in the docs and it's working well.

On a side question: Is there a way I could access the resource usage of the nodes through a REST API (using their endpoint) ? I can't seem to get the path correctly, I tried running kubectl proxy and then accessing the resource usage metrics for node-1 : http://localhost:8001/api/v1/nodes/node-1/metrics/resource, but 'm getting 404 error.
I'd appreciate if you could point me in the right direction regarding this !

Thanks

[wzshiming]

That's an independent API, http://localhost:8001/apis/metrics.k8s.io/v1beta1/nodes.

And existing clients that you can use directly
https://github.com/kubernetes/metrics/blob/master/pkg/client/clientset/versioned/typed/metrics/v1beta1/metrics_client.go