KubernetesClientCertificateExpiresNextWeek

KubernetesClientCertificateExpiresNextWeek #

A client certificate used to authenticate to the apiserver is expiring next week.

Alert Rule
alert: KubernetesClientCertificateExpiresNextWeek
annotations:
  description: |-
    A client certificate used to authenticate to the apiserver is expiring next week.
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/kubestate-exporter/kubernetesclientcertificateexpiresnextweek/
  summary: Kubernetes client certificate expires next week (instance {{ $labels.instance
    }})
expr: apiserver_client_certificate_expiration_seconds_count{job="apiserver"} > 0 and
  histogram_quantile(0.01, sum by (job, le) (rate(apiserver_client_certificate_expiration_seconds_bucket{job="apiserver"}[5m])))
  < 7*24*60*60
for: 0m
labels:
  severity: warning

Meaning #

The KubernetesClientCertificateExpiresNextWeek alert is triggered when a client certificate used to authenticate to the Kubernetes API server is approaching expiration. This alert is warning us that the certificate will expire within the next week, which can lead to authentication issues and potentially disrupt cluster operations.

Impact #

If this alert is not addressed, the expiring client certificate can cause:

  • Authentication errors for clients using the affected certificate
  • Disruption to Kubernetes cluster operations and management
  • Potential security risks if the expired certificate is not properly rotated

Diagnosis #

To diagnose the issue, follow these steps:

  1. Identify the affected certificate by checking the apiserver_client_certificate_expiration_seconds_count metric in Prometheus.
  2. Investigate the apiserver_client_certificate_expiration_seconds_bucket metric to determine the exact expiration time of the certificate.
  3. Verify the instance and job labels associated with the alert to identify the specific Kubernetes component or pod affected.

Mitigation #

To mitigate the issue, follow these steps:

  1. Identify the responsible team or individual for managing client certificates in the Kubernetes cluster.
  2. Rotate the expiring client certificate by generating a new certificate and updating the corresponding configuration.
  3. Verify that the new certificate is properly configured and deployed to the affected component or pod.
  4. Monitor the apiserver_client_certificate_expiration_seconds_count metric to ensure the issue is resolved.

Additional resources:

  • Refer to the Kubernetes documentation for guidance on managing client certificates and authentication.
  • Review the runbook for this alert on GitHub for more detailed steps and troubleshooting tips.
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