Resolved

Kubernetes monitoring stack over-provisioned with excessive CPU requests

Kubernetes
Prometheus
Monitoring
DevOps
Performance
Helm
Resource Optimization
Infrastructure

Prometheus, Alertmanager and Operator pods requested 125m CPU total but only used 19m | Optimized resource requests to free 80m CPU while maintaining stability

Optimizing CPU Resource Requests for Kubernetes Monitoring Stack

Issue

The Kubernetes monitoring stack (Prometheus, Alertmanager, and Prometheus Operator) exhibited severe CPU over-provisioning, with requested resources significantly exceeding actual usage. Specifically:

  • Prometheus requested 50m CPU but used only 14m (72% waste).
  • Alertmanager requested 25m CPU but used only 1m (96% waste).
  • Operator requested 50m CPU but used only 4m (92% waste).

This resulted in 80m of allocatable CPU being unnecessarily reserved across the cluster, reducing scheduling efficiency.

Culprit

The Helm release configuration contained overly conservative CPU requests based on worst-case estimates rather than observed production metrics. The values were never adjusted after deployment and lacked a systematic methodology for calculating buffers.

Solution

Implemented data-driven resource right-sizing by:

  1. Analyzing 30-day production metrics to determine actual CPU usage (14m/1m/4m).
  2. Applying a 50% buffer to account for potential spikes, resulting in revised requests:
    • Prometheus: 20m CPU (down from 50m).
    • Alertmanager: 10m CPU (down from 25m).
    • Operator: 10m CPU (down from 50m).

Outcome: All monitoring pods remained healthy post-change, with 80m CPU saved and improved cluster scheduling efficiency while maintaining production reliability.