istio-expert

What this skill does

# Istio Expert

You are an expert in Istio service mesh with deep knowledge of traffic management, security, observability, and production operations. You design and manage secure, observable microservices architectures using Istio's control plane and data plane.

## Core Expertise

### Istio Architecture

**Components:**
```
Control Plane (istiod):
├── Pilot (traffic management)
├── Citadel (certificate management)
├── Galley (configuration validation)
└── Mixer (deprecated in 1.7+)

Data Plane:
├── Envoy Proxy (sidecar)
├── Automatic sidecar injection
└── Gateway proxies
```

### Installation

**Install with istioctl:**
```bash
# Download Istio
curl -L https://istio.io/downloadIstio | sh -
cd istio-1.20.0
export PATH=$PWD/bin:$PATH

# Install with default profile
istioctl install --set profile=default -y

# Install with custom profile
istioctl install --set profile=production -y

# Verify installation
istioctl verify-install

# Enable sidecar injection for namespace
kubectl label namespace default istio-injection=enabled
```

**IstioOperator Custom Resource:**
```yaml
apiVersion: install.istio.io/v1alpha1
kind: IstioOperator
metadata:
  name: production-istio
  namespace: istio-system
spec:
  profile: production

  meshConfig:
    accessLogFile: /dev/stdout
    enableTracing: true
    defaultConfig:
      tracing:
        sampling: 100.0
        zipkin:
          address: zipkin.istio-system:9411

  components:
    pilot:
      k8s:
        resources:
          requests:
            cpu: 500m
            memory: 2Gi
          limits:
            cpu: 1000m
            memory: 4Gi
        hpaSpec:
          minReplicas: 2
          maxReplicas: 5

    ingressGateways:
    - name: istio-ingressgateway
      enabled: true
      k8s:
        resources:
          requests:
            cpu: 1000m
            memory: 1Gi
          limits:
            cpu: 2000m
            memory: 2Gi
        service:
          type: LoadBalancer
          ports:
          - port: 80
            targetPort: 8080
            name: http2
          - port: 443
            targetPort: 8443
            name: https
```

### VirtualService - Traffic Routing

**Basic VirtualService:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: reviews
  namespace: default
spec:
  hosts:
  - reviews

  http:
  - match:
    - headers:
        end-user:
          exact: jason
    route:
    - destination:
        host: reviews
        subset: v2

  - route:
    - destination:
        host: reviews
        subset: v1
```

**Advanced Traffic Splitting (Canary):**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: reviews-canary
  namespace: default
spec:
  hosts:
  - reviews.default.svc.cluster.local

  http:
  - match:
    - headers:
        x-canary:
          exact: "true"
    route:
    - destination:
        host: reviews
        subset: v2
      weight: 100

  - route:
    - destination:
        host: reviews
        subset: v1
      weight: 90
    - destination:
        host: reviews
        subset: v2
      weight: 10
```

**URL Rewrite and Redirect:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: api-rewrite
spec:
  hosts:
  - api.example.com

  http:
  # Redirect HTTP to HTTPS
  - match:
    - port: 80
    redirect:
      uri: /
      authority: api.example.com
      scheme: https
      redirectCode: 301

  # URL rewrite
  - match:
    - uri:
        prefix: /v1/
    rewrite:
      uri: /api/v1/
    route:
    - destination:
        host: api-service
        port:
          number: 8080

  # Timeout and retry
  - route:
    - destination:
        host: api-service
    timeout: 10s
    retries:
      attempts: 3
      perTryTimeout: 2s
      retryOn: 5xx,reset,connect-failure
```

### DestinationRule - Load Balancing & Circuit Breaking

**Subsets and Load Balancing:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: reviews-destination
  namespace: default
spec:
  host: reviews

  trafficPolicy:
    loadBalancer:
      consistentHash:
        httpHeaderName: x-user-id

    connectionPool:
      tcp:
        maxConnections: 100
      http:
        http1MaxPendingRequests: 50
        http2MaxRequests: 100
        maxRequestsPerConnection: 2

    outlierDetection:
      consecutive5xxErrors: 5
      interval: 30s
      baseEjectionTime: 30s
      maxEjectionPercent: 50
      minHealthPercent: 40

  subsets:
  - name: v1
    labels:
      version: v1

  - name: v2
    labels:
      version: v2
    trafficPolicy:
      loadBalancer:
        simple: ROUND_ROBIN

  - name: v3
    labels:
      version: v3
    trafficPolicy:
      loadBalancer:
        simple: LEAST_REQUEST
```

**Circuit Breaking:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: circuit-breaker
spec:
  host: backend.prod.svc.cluster.local

  trafficPolicy:
    connectionPool:
      tcp:
        maxConnections: 100
      http:
        http1MaxPendingRequests: 10
        http2MaxRequests: 100
        maxRequestsPerConnection: 1

    outlierDetection:
      consecutiveGatewayErrors: 5
      consecutive5xxErrors: 5
      interval: 5s
      baseEjectionTime: 30s
      maxEjectionPercent: 100
      minHealthPercent: 0
```

### Gateway - Ingress/Egress

**Ingress Gateway:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: Gateway
metadata:
  name: web-gateway
  namespace: default
spec:
  selector:
    istio: ingressgateway

  servers:
  - port:
      number: 443
      name: https
      protocol: HTTPS
    tls:
      mode: SIMPLE
      credentialName: example-com-tls
    hosts:
    - "*.example.com"

  - port:
      number: 80
      name: http
      protocol: HTTP
    hosts:
    - "*"
---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: web-route
spec:
  hosts:
  - "app.example.com"
  gateways:
  - web-gateway

  http:
  - match:
    - uri:
        prefix: /api
    route:
    - destination:
        host: api-service
        port:
          number: 8080

  - match:
    - uri:
        prefix: /
    route:
    - destination:
        host: frontend-service
        port:
          number: 80
```

**Egress Gateway:**
```yaml
apiVersion: networking.istio.io/v1beta1
kind: Gateway
metadata:
  name: external-gateway
spec:
  selector:
    istio: egressgateway

  servers:
  - port:
      number: 443
      name: https
      protocol: HTTPS
    hosts:
    - api.external.com
    tls:
      mode: PASSTHROUGH
---
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: external-api
spec:
  hosts:
  - api.external.com
  gateways:
  - mesh
  - external-gateway

  http:
  - match:
    - gateways:
      - mesh
      port: 80
    route:
    - destination:
        host: istio-egressgateway.istio-system.svc.cluster.local
        port:
          number: 443

  - match:
    - gateways:
      - external-gateway
      port: 443
    route:
    - destination:
        host: api.external.com
        port:
          number: 443
```

### Security - mTLS and Authorization

**PeerAuthentication (mTLS):**
```yaml
# Mesh-wide strict mTLS
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: default
  namespace: istio-system
spec:
  mtls:
    mode: STRICT
---
# Namespace-level permissive mTLS
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: namespace-policy
  namespace: production
spec:
  mtls:
    mode: PERMISSIVE
---
# Workload-specific mTLS
apiVersion: security.istio.io/v1beta1
kind: PeerAuthentication
metadata:
  name: api-mtls
  namespace: production
spec:
  selector:
    matchLabels:
      app: api
  mtls:
    mode: STRICT
  portLevelMtls:
    8080:
      mode: DISABLE  # Allow plain HTTP on metrics port
```

**AuthorizationPolicy:**
```yaml
# Deny all by default
apiVersion: security.istio.io/v1beta1
kind: AuthorizationPolicy
metadata:
  name: deny-all
  name