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Troubleshooting & Debugging

Common Issues, Solutions, Logging, and Performance Optimization

Debugging Kubernetes Issues

Issues in Kubernetes can be complex and multi-layered. This guide provides systematic approaches to troubleshooting, common problems and their solutions, debugging techniques, and performance optimization strategies.

Essential Debugging Tools & Commands

Master these commands for effective troubleshooting

Pod Status & Information

# Get pod status kubectl get pods -n default # Detailed pod info kubectl describe pod # View pod events kubectl get events --sort-by='.lastTimestamp' # Check pod logs kubectl logs kubectl logs -f # Follow logs

Exec & Port Forward

# Execute commands in pod kubectl exec -it -- /bin/sh # Port forwarding kubectl port-forward 8080:8080 # Copy files kubectl cp :/path/to/file ./local/path

Resource & Node Info

# Node status kubectl get nodes kubectl describe node # Resource usage kubectl top nodes kubectl top pods # Node capacity kubectl describe nodes | grep Capacity -A 5

Common Issues & Solutions

Quick reference for typical problems

Issue: Pod Stuck in Pending

Pod is created but not assigned to any node.

Solution:

# Check node resources kubectl top nodes # Check for node selector issues kubectl describe pod # Check resource quota kubectl describe quota -n

Common causes: Insufficient cluster resources, node affinity issues, or resource quotas exceeded.

Issue: CrashLoopBackOff Status

Container starts, crashes, and restarts continuously.

Solution:

# Check logs kubectl logs --previous # Detailed event information kubectl describe pod # Check liveness probe settings kubectl get pod -o yaml

Common causes: Application errors, misconfigured health probes, missing dependencies, or failed initialization.

Issue: ImagePullBackOff

Kubernetes cannot pull the container image.

Solution:

# Verify image name and tag kubectl describe pod # Check credentials kubectl get secrets # Create image pull secret kubectl create secret docker-registry myregistrykey \ --docker-server= \ --docker-username= \ --docker-password=

Common causes: Wrong image name, non-existent tag, authentication issues, or private registry access problems.

Performance Optimization & Monitoring

Improve cluster and application performance

Resource Optimization

  • Right-size CPU/memory requests based on actual usage
  • Use Horizontal Pod Autoscaling (HPA)
  • Implement pod disruption budgets
  • Use node affinity for optimal placement

Monitoring Tools

  • Prometheus - Metrics collection
  • Grafana - Visualization
  • ELK Stack - Logging
  • Jaeger - Distributed tracing

Key Metrics to Monitor

  • CPU and memory usage
  • Pod restart counts
  • Network I/O throughput
  • API server response times

Logging & Log Analysis

Effective logging strategies

Logging Best Practices

# View pod logs kubectl logs # Tail logs in real-time kubectl logs -f # View logs for previous crashed container kubectl logs --previous # Get logs from all containers in a pod kubectl logs --all-containers=true # Stream logs from multiple pods kubectl logs -f -l app=myapp --max-log-requests=10

Log aggregation setup: