[aws-cloudwatch-metrics] fix: grant permission to scrape api server metrics - Failed to scrape Prometheus endpoint

[tdharris]

Issue

#1098 - Failed to scrape Prometheus endpoint

The CloudWatch agent fails to scrape metrics from the control plane, resulting in logs with Failed to scrape Prometheus endpoint and a 401 Unauthorized error.

{
    "caller": "internal/transaction.go:123",
    "msg": "Failed to scrape Prometheus endpoint",
    "kind": "receiver",
    "name": "awscontainerinsightreceiver",
    "data_type": "metrics",
    "scrape_timestamp": 1760551208877,
    "target_labels": "{ClusterName=\"eks-clustername\", NodeName=\"<ip-redacted>.<region-redacted>.compute.internal\", Sources=\"[\\\"apiserver\\\"]\", Type=\"ControlPlane\", Version=\"0\", __name__=\"up\", instance=\"172.20.0.1:443\", job=\"containerInsightsKubeAPIServerScraper/172.20.0.1\"}"
}

Description of changes

It appears the existing ClusterRole for the agent's service account lacks the permission to access this non-resource URL.

This change resolves the issue by adding a new rule to the ClusterRole, granting the get verb for the nonResourceURLs path /metrics. This permission allows the agent to successfully authenticate and scrape the control plane's Prometheus metrics.

See Metrics For Kubernetes System Components:

"If your cluster uses RBAC, reading metrics requires authorization via a user, group or ServiceAccount with a ClusterRole that allows accessing /metrics. For example:"

apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata:
  name: prometheus
rules:
  - nonResourceURLs:
      - "/metrics"
    verbs:
      - get

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

I have duplicated the error mentioned above using the latest 0.0.11 version of this chart and have adjusted the existing cluster role to include the updated permission and verified I no longer see the error repeated.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[tdharris]

@jayanthvn, hoping you might be able to offer a review if possible. Thanks so much for your time!