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Scenario #451
Scaling & Load
Kubernetes v1.26, Azure AKS

Inconsistent Scaling Due to Misconfigured Horizontal Pod Autoscaler

Horizontal Pod Autoscaler (HPA) inconsistently scaled pods based on incorrect metric definitions.

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What Happened

HPA failed to scale up correctly because it was configured to trigger based on custom metrics, but the metric source was unreliable.

Diagnosis Steps
  • 1Reviewed HPA configuration and identified incorrect metric configuration.
  • 2Logs showed HPA was relying on a custom metric, which sometimes reported outdated or missing data.
Root Cause

Misconfigured custom metrics in the HPA setup, leading to inconsistent scaling decisions.

Fix/Workaround
• Switched to using Kubernetes-native CPU and memory metrics for autoscaling.
• Improved the reliability of the custom metrics system by implementing fallback mechanisms.
Lessons Learned

Custom metrics should be tested for reliability before being used in autoscaling decisions.

How to Avoid
  • 1Regularly monitor and validate the health of custom metrics.
  • 2Use native Kubernetes metrics for critical scaling decisions when possible.