CorednsPanicCount

CorednsPanicCount #

Number of CoreDNS panics encountered

Alert Rule
alert: CorednsPanicCount
annotations:
  description: |-
    Number of CoreDNS panics encountered
      VALUE = {{ $value }}
      LABELS = {{ $labels }}    
  runbook: https://srerun.github.io/prometheus-alerts/runbooks/coredns-internal/corednspaniccount/
  summary: CoreDNS Panic Count (instance {{ $labels.instance }})
expr: increase(coredns_panics_total[1m]) > 0
for: 0m
labels:
  severity: critical

Here is a runbook for the CorednsPanicCount alert rule:

Meaning #

The CorednsPanicCount alert is triggered when the CoreDNS server experiences one or more panic events within a 1-minute window. This indicates that the CoreDNS process has encountered a critical error that causes it to crash or terminate abnormally.

Impact #

The impact of this alert is high, as a CoreDNS panic can lead to:

  • Loss of DNS resolution functionality
  • Increased latency or timeouts for DNS queries
  • Potential disruption to dependent applications and services
  • Decreased overall system reliability and availability

Diagnosis #

To diagnose the root cause of the CoreDNS panic, follow these steps:

  1. Check the CoreDNS logs: Review the CoreDNS logs to identify the specific error or condition that led to the panic.
  2. Verify system resource utilization: Check the system resources (CPU, memory, disk space) to ensure they are within healthy limits.
  3. Investigate recent changes: Review recent changes to the CoreDNS configuration, plugins, or underlying system to identify potential causes of the panic.
  4. Run a CoreDNS debug session: Enable debug logging for CoreDNS and reproduce the issue to gather more detailed information.

Mitigation #

To mitigate the effects of the CoreDNS panic, follow these steps:

  1. Restart the CoreDNS service: Immediately restart the CoreDNS service to restore DNS functionality.
  2. Investigate and address root cause: Perform a thorough investigation to identify and address the root cause of the panic, following the diagnosis steps above.
  3. Implement additional monitoring and alerting: Enhance monitoring and alerting to detect potential issues before they lead to a CoreDNS panic.
  4. Consider implementing a CoreDNS cluster: If the CoreDNS instance is critical to the system, consider implementing a CoreDNS cluster to provide redundancy and high availability.
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