The Splunk Collector for Kubernetes is missing metrics starting with k8s.pod.* and k8s.node.*

After deploying the Splunk Distribution of the OpenTelemetry Collector for Kubernetes Chart version 0.87.0 or higher as either a new install or upgrade, the following pod and node metrics are not collected:

• k8s.(pod/node).cpu.time

• k8s.(pod/node).cpu.utilization

• k8s.(pod/node).filesystem.available

• k8s.(pod/node).filesystem.capacity

• k8s.(pod/node).filesystem.usage

• k8s.(pod/node).memory.available

• k8s.(pod/node).memory.major_page_faults

• k8s.(pod/node).memory.page_faults

• k8s.(pod/node).memory.rss

• k8s.(pod/node).memory.usage

• k8s.(pod/node).memory.working_set

• k8s.(pod/node).network.errors

• k8s.(pod/node).network.io

Confirm the metrics are missing

To confirm these metrics are missing, perform the following steps:

1. Confirm that the metrics are missing with the following Search Processing Language (SPL) command:

   | mstats count(_value) as "Val" where index="otel_metrics_0_93_3" AND metric_name IN (k8s.pod.*, k8s.node.*) by metric_name

2. Check the Collector’s pod logs from the CLI of the Kubernetes node with this command:

   kubectl -n {namespace} logs {collector-agent-pod-name}

   Note: Update namespace and collector-agent-pod-name based on your environment.

3. Check that you see a "tls: failed to verify certificate" error similar to the following example in the agent pod logs:

   2024-02-28T01:11:24.614Z    error   scraperhelper/scrapercontroller.go:200  Error scraping metrics  {"kind": "receiver", "name": "kubeletstats", "data_type": "metrics", "error": "Get \"https://10.202.38.255:10250/stats/summary\": tls: failed to verify certificate: x509: cannot validate certificate for 10.202.38.255 because it doesn't contain any IP SANs", "scraper": "kubeletstats"}
   go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).scrapeMetricsAndReport
     go.opentelemetry.io/collector/receiver@v0.93.0/scraperhelper/scrapercontroller.go:200
   go.opentelemetry.io/collector/receiver/scraperhelper.(*controller).startScraping.func1
     go.opentelemetry.io/collector/receiver@v0.93.0/scraperhelper/scrapercontroller.go:176

Resolution

The Kubelet stats receiver collects k8s.(pod or node) metrics from the Kubernetes endpoint /stats/summary. As of version 0.87.0 of the Splunk OTel Collector the kubelet certificate is verified during this process to confirm it’s valid. If you are using a self signed or invalid certificate the Kubelet stats receiver cannot collect the metrics.

You have the following alternatives to resolve this error:

1. Add valid a certificate to your Kubernetes cluster. See how at Configure the Collector for Kubernetes with Helm. After updating the values.yaml file use the Helm upgrade command to upgrade your Collector deployment.

2. Turn off certificate verification in the OTel agent Kubelet Stats receiver by setting insecure_skip_verify: true for the Kubelet stats receiver in the agent.config section of the values.yaml file.

For example, use this configuration to turn off certificate verification:

agent:
  config:
    receivers:
      kubeletstats:
        insecure_skip_verify: true