Q: Your HPA (Horizontal Pod Autoscaler) is not scaling up even though CPU usage is high. Why?
HPA needs metrics-server to be installed and working. Without it, HPA can't read CPU/memory metrics and shows <unknown> in kubectl get hpa.
#Kubernetes #Troubleshooting & Debugging #L2 #Container Orchestration #K8s
🎙️ Candidate Opening & Architectural Context
""In one of our high-traffic production clusters, our SRE team handled this incident using a standardized runbook. The interviewer is testing: HPA prerequisites and metrics-server dependency.. I structure my answer around systematic triage first, root cause analysis second, and permanent remediation third.""
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🛠️ Production Runbook & Step-by-Step Resolution
1️⃣
Initial Diagnostics & Root Cause Analysis
HPA needs metrics-server to be installed and working. Without it, HPA can't read CPU/memory metrics and shows kubectl get hpa.
kubectl get hpa— if it shows/50% kubectl top pods— if this fails, metrics-server is the problem.- Also check that pods have resource requests defined — HPA calculates usage as a percentage of the request value. No requests = HPA can't calculate.
2️⃣
Remediation & Permanent Safeguards
Check: Fix: Install metrics-server, set resource requests on pods.
💡 The Senior SRE Gold Nugget (Key Architectural Takeaway)
"Pro-Tip: kubectl get hpa — if it shows /50% for current metric, metrics-server is missing or broken.."
⚡ 60-Second Elevator Pitch Talking Points
- kubectl get hpa — if it shows /50% for current metric, metrics-server is missing or broken.
- kubectl top pods — if this fails, metrics-server is the problem.
- Also check that pods have resource requests defined — HPA calculates usage as a percentage of the...
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