Introduce k8s.volume.used metric

[odubajDT]

Component(s)

receiver/kubeletstats

Is your feature request related to a problem? Please describe.

Volume usage is the only information that is not exposed by the kubeletstats receiver, even if the information from the /stats/summary endpoint is present. It would be very useful to have this information exposed via a dedicated metric, following the existing pattern.

Snippet from the /stats/summary endpoint:

"volume": [
    {
     "time": "2025-06-03T07:40:12Z",
     "availableBytes": 52416512,
     "capacityBytes": 52428800,
     "usedBytes": 12288,
     "inodesFree": 1526875,
     "inodes": 1526885,
     "inodesUsed": 9,
     "name": "kube-api-access-mzh62"
    }
   ],

Describe the solution you'd like

Export k8s.volume.used metric

Describe alternatives you've considered

None

Additional context

No response

[github-actions]

Pinging code owners:

• receiver/kubeletstats: @dmitryax @TylerHelmuth @ChrsMark

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[ChrsMark]

There is an ongoing PR for adding this (along with the existing ones) as Semantic Conventions: open-telemetry/semantic-conventions#2319