Istio Traffic Management

# 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

```yaml
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

```yaml
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

```yaml
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

```yaml
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

```yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: mirror-tr