Performance Considerations

Performance Considerations

Network Policies impact packet processing performance, though effects vary significantly by implementation. CNI plugins implement policies differently, with some using kernel eBPF programs for efficiency while others rely on iptables rules. Understanding performance characteristics helps architects choose appropriate CNI plugins and design policies that balance security with performance.

Policy complexity affects processing overhead. Policies with numerous rules or complex selectors require more processing per packet. Consolidating policies where possible reduces overhead. However, overly broad policies compromise security. Teams must balance policy granularity with performance requirements, using monitoring to identify bottlenecks.

# Optimized policy combining multiple similar rules
apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: microservices-communication
  namespace: production
spec:
  podSelector:
    matchLabels:
      network-policy: microservices
  policyTypes:
  - Ingress
  - Egress
  ingress:
  # Combined ingress from multiple services
  - from:
    - podSelector:
        matchExpressions:
        - key: app
          operator: In
          values: 
          - frontend
          - api-gateway
          - batch-processor
    ports:
    - protocol: TCP
      port: 8080
    - protocol: TCP
      port: 8443
  egress:
  # Combined egress to backend services
  - to:
    - podSelector:
        matchExpressions:
        - key: tier
          operator: In
          values:
          - backend
          - cache
          - database

Scale testing helps identify performance limits before production deployment. Gradually increasing policy count and complexity while monitoring latency and throughput reveals breaking points. This testing should reflect production patterns, including peak traffic periods and failure scenarios. Results guide capacity planning and architecture decisions.