add convention attribute for k8s cluster version

[frzifus]

What are you trying to achieve?

It would be nice to support cluster versions. Cluster upgrades can cause problems with software that communicates with this api. But I'am missing a convention entry for k8s cluster version equal to the cluster name (conventions.AttributeK8SClusterName).

What did you expect to see?
An entry like conventions.AttributeK8SClusterVersion = "k8s.cluster.version".

Additional context.

This is related to the OpenShift metadata provider implementation in otelcol-contrib.

[arminru]

Hey @frzifus!
This is about the version of k8s itself and not the services deployed on it, right?
Is this something specific to OpenShift or can this value be retrieved for all k8s implementations?

[frzifus]

Hi @arminru,
you are right. The version info is coming from the k8s API itself. There is a /version endpoint that is also used by kubectl version.

Example Kubernetes API request..

$ curl -H "Authorization: Bearer ${AUTH_TOKEN}" "https://api-k8s.example.com:6443/version"                               

{
  "major": "1",
  "minor": "21",
  "gitVersion": "v1.21.11+5cc9227",
  "gitCommit": "047f86f8e2212f25394de1c8bad35d9426ae0f4c",
  "gitTreeState": "clean",
  "buildDate": "2022-09-20T16:39:45Z",
  "goVersion": "go1.16.12",
  "compiler": "gc",
  "platform": "linux/amd64"
}

Is this something specific to OpenShift or can this value be retrieved for all k8s implementations?

It is Kubernetes specific. While working on the openshift resource proccessor support, i noticed it would be even better to introduce a openshift and kubernetes version too. I assume i would need to create another Issue + PR for that?

Constant	Value	Example
conventions.AttributeK8SClusterVersion	k8s.cluster.version	v1.21.11+5cc9227
conventions.AttributeOpenShiftClusterVersion	openshift.cluster.version	4.8.51

What are your thoughts on that?