Istio Traffic Management

Comprehensive guide to Istio traffic management for production service mesh deployments.

When to Use This Skill Configuring service-to-service routing Implementing canary or blue-green deployments Setting up circuit breakers and retries Load balancing configuration Traffic mirroring for testing Fault injection for chaos engineering Core Concepts 1. Traffic Management Resources Resource Purpose Scope VirtualService Route traffic to destinations Host-based DestinationRule Define policies after routing Service-based Gateway Configure ingress/egress Cluster edge ServiceEntry Add external services Mesh-wide 2. Traffic Flow Client → Gateway → VirtualService → DestinationRule → Service (routing) (policies) (pods)

Templates Template 1: Basic Routing apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: reviews-route namespace: bookinfo spec: hosts: - reviews http: - match: - headers: end-user: exact: jason route: - destination: host: reviews subset: v2 - route: - destination: host: reviews subset: v1

apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: reviews-destination namespace: bookinfo spec: host: reviews subsets: - name: v1 labels: version: v1 - name: v2 labels: version: v2 - name: v3 labels: version: v3

Template 2: Canary Deployment apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: my-service-canary spec: hosts: - my-service http: - route: - destination: host: my-service subset: stable weight: 90 - destination: host: my-service subset: canary weight: 10

apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: my-service-dr spec: host: my-service trafficPolicy: connectionPool: tcp: maxConnections: 100 http: h2UpgradePolicy: UPGRADE http1MaxPendingRequests: 100 http2MaxRequests: 1000 subsets: - name: stable labels: version: stable - name: canary labels: version: canary

Template 3: Circuit Breaker apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: circuit-breaker spec: host: my-service trafficPolicy: connectionPool: tcp: maxConnections: 100 http: http1MaxPendingRequests: 100 http2MaxRequests: 1000 maxRequestsPerConnection: 10 maxRetries: 3 outlierDetection: consecutive5xxErrors: 5 interval: 30s baseEjectionTime: 30s maxEjectionPercent: 50 minHealthPercent: 30

Template 4: Retry and Timeout apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: ratings-retry spec: hosts: - ratings http: - route: - destination: host: ratings timeout: 10s retries: attempts: 3 perTryTimeout: 3s retryOn: connect-failure,refused-stream,unavailable,cancelled,retriable-4xx,503 retryRemoteLocalities: true

Template 5: Traffic Mirroring apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: mirror-traffic spec: hosts: - my-service http: - route: - destination: host: my-service subset: v1 mirror: host: my-service subset: v2 mirrorPercentage: value: 100.0

Template 6: Fault Injection apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: fault-injection spec: hosts: - ratings http: - fault: delay: percentage: value: 10 fixedDelay: 5s abort: percentage: value: 5 httpStatus: 503 route: - destination: host: ratings

Template 7: Ingress Gateway apiVersion: networking.istio.io/v1beta1 kind: Gateway metadata: name: my-gateway spec: selector: istio: ingressgateway servers: - port: number: 443 name: https protocol: HTTPS tls: mode: SIMPLE credentialName: my-tls-secret hosts: - "*.example.com"

apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: my-vs spec: hosts: - "api.example.com" gateways: - my-gateway http: - match: - uri: prefix: /api/v1 route: - destination: host: api-service port: number: 8080

Load Balancing Strategies apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: load-balancing spec: host: my-service trafficPolicy: loadBalancer: simple: ROUND_ROBIN # or LEAST_CONN, RANDOM, PASSTHROUGH

Consistent hashing for sticky sessions

apiVersion: networking.istio.io/v1beta1 kind: DestinationRule metadata: name: sticky-sessions spec: host: my-service trafficPolicy: loadBalancer: consistentHash: httpHeaderName: x-user-id # or: httpCookie, useSourceIp, httpQueryParameterName

Best Practices Do's Start simple - Add complexity incrementally Use subsets - Version your services clearly Set timeouts - Always configure reasonable timeouts Enable retries - But with backoff and limits Monitor - Use Kiali and Jaeger for visibility Don'ts Don't over-retry - Can cause cascading failures Don't ignore outlier detection - Enable circuit breakers Don't mirror to production - Mirror to test environments Don't skip canary - Test with small traffic percentage first Debugging Commands

Check VirtualService configuration

istioctl analyze

View effective routes

istioctl proxy-config routes deploy/my-app -o json

Check endpoint discovery

istioctl proxy-config endpoints deploy/my-app

Debug traffic

istioctl proxy-config log deploy/my-app --level debug

Resources Istio Traffic Management Virtual Service Reference Destination Rule Reference