路由

Istio 的高级路由功能可根据各种请求属性对流量进行精细控制。

目录

1. 路由概览
2. 匹配条件
3. 基于 URI 的路由
4. 基于 Header 的路由
5. 基于查询参数的路由
6. 基于 HTTP 方法的路由
7. 基于来源的路由
8. 优先级和回退
9. 实际示例
10. 故障排除

路由概览

VirtualService 路由规则由匹配条件和路由目标组成。

基本结构

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: routing-example
spec:
  hosts:
  - myapp.example.com
  http:
  - match:
    - uri:
        prefix: "/api/v1"
    route:
    - destination:
        host: api-v1
  - match:
    - headers:
        user-agent:
          regex: ".*Mobile.*"
    route:
    - destination:
        host: mobile-app
  - route:  # Default route (no match)
    - destination:
        host: web-app

匹配条件

匹配条件类型

条件	描述	匹配类型
uri	请求路径	exact、prefix、regex
scheme	HTTP/HTTPS	exact、prefix、regex
method	HTTP 方法	exact、prefix、regex
authority	Host Header	exact、prefix、regex
headers	HTTP Header	exact、prefix、regex
queryParams	查询参数	exact、prefix、regex
sourceLabels	来源工作负载标签	标签选择器
gateways	Gateway 名称	列表

匹配类型

# exact: Exact match
match:
- uri:
    exact: "/login"

# prefix: Prefix match
match:
- uri:
    prefix: "/api/"

# regex: Regular expression match
match:
- uri:
    regex: "^/api/v[0-9]+/.*"

组合多个条件

# AND condition: All conditions must match
http:
- match:
  - uri:
      prefix: "/api"
    headers:
      x-api-version:
        exact: "v2"
    queryParams:
      debug:
        exact: "true"
  route:
  - destination:
      host: api-debug

# OR condition: Use multiple match blocks
http:
- match:
  - uri:
      prefix: "/api/v1"
  - uri:
      prefix: "/api/v2"
  route:
  - destination:
      host: api-service

基于 URI 的路由

前缀匹配

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: uri-prefix-routing
spec:
  hosts:
  - myapp.example.com
  http:
  # API traffic
  - match:
    - uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-service
        port:
          number: 8080

  # Admin traffic
  - match:
    - uri:
        prefix: "/admin/"
    route:
    - destination:
        host: admin-service
        port:
          number: 9000

  # Static files
  - match:
    - uri:
        prefix: "/static/"
    route:
    - destination:
        host: static-service
        port:
          number: 8000

  # Default traffic
  - route:
    - destination:
        host: frontend-service
        port:
          number: 3000

精确匹配

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: uri-exact-routing
spec:
  hosts:
  - myapp.example.com
  http:
  # Login page
  - match:
    - uri:
        exact: "/login"
    route:
    - destination:
        host: auth-service

  # Logout
  - match:
    - uri:
        exact: "/logout"
    route:
    - destination:
        host: auth-service

  # Health check
  - match:
    - uri:
        exact: "/health"
    route:
    - destination:
        host: health-service

正则表达式匹配

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: uri-regex-routing
spec:
  hosts:
  - myapp.example.com
  http:
  # API version routing: /api/v1/, /api/v2/, etc.
  - match:
    - uri:
        regex: "^/api/v[0-9]+/.*"
    route:
    - destination:
        host: api-service

  # Numeric resource ID: /users/123
  - match:
    - uri:
        regex: "^/users/[0-9]+$"
    route:
    - destination:
        host: user-service

  # File extension: .jpg, .png, .gif
  - match:
    - uri:
        regex: ".*\\.(jpg|png|gif)$"
    route:
    - destination:
        host: image-service

基于 Header 的路由

基于 User-Agent 的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: header-user-agent-routing
spec:
  hosts:
  - reviews
  http:
  # Mobile devices
  - match:
    - headers:
        user-agent:
          regex: ".*Mobile.*"
    route:
    - destination:
        host: reviews
        subset: mobile

  # Tablet devices
  - match:
    - headers:
        user-agent:
          regex: ".*(iPad|Tablet).*"
    route:
    - destination:
        host: reviews
        subset: tablet

  # Desktop (default)
  - route:
    - destination:
        host: reviews
        subset: desktop

基于自定义 Header 的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: header-custom-routing
spec:
  hosts:
  - myapp
  http:
  # Developer/Tester routing
  - match:
    - headers:
        x-dev-user:
          exact: "true"
    route:
    - destination:
        host: myapp
        subset: dev

  # Beta testers
  - match:
    - headers:
        x-beta-tester:
          exact: "true"
    route:
    - destination:
        host: myapp
        subset: beta

  # VIP users
  - match:
    - headers:
        x-user-tier:
          exact: "vip"
    route:
    - destination:
        host: myapp
        subset: vip

  # Regular users
  - route:
    - destination:
        host: myapp
        subset: stable

基于 API 版本的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: header-api-version-routing
spec:
  hosts:
  - api.example.com
  http:
  # API v3
  - match:
    - headers:
        x-api-version:
          exact: "v3"
    route:
    - destination:
        host: api-service
        subset: v3

  # API v2
  - match:
    - headers:
        x-api-version:
          exact: "v2"
    route:
    - destination:
        host: api-service
        subset: v2

  # API v1 (default)
  - route:
    - destination:
        host: api-service
        subset: v1

基于查询参数的路由

基本查询参数匹配

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: query-param-routing
spec:
  hosts:
  - search.example.com
  http:
  # Debug mode: ?debug=true
  - match:
    - queryParams:
        debug:
          exact: "true"
    route:
    - destination:
        host: search-service
        subset: debug

  # Premium search: ?premium=1
  - match:
    - queryParams:
        premium:
          exact: "1"
    route:
    - destination:
        host: search-service
        subset: premium

  # A/B testing: ?variant=b
  - match:
    - queryParams:
        variant:
          exact: "b"
    route:
    - destination:
        host: search-service
        subset: variant-b

  # Default search
  - route:
    - destination:
        host: search-service
        subset: standard

组合多个查询参数

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: query-param-combined-routing
spec:
  hosts:
  - api.example.com
  http:
  # Debug mode + verbose logging
  - match:
    - queryParams:
        debug:
          exact: "true"
        verbose:
          exact: "true"
    route:
    - destination:
        host: api-service
        subset: debug-verbose

  # Debug mode only
  - match:
    - queryParams:
        debug:
          exact: "true"
    route:
    - destination:
        host: api-service
        subset: debug

  # Normal mode
  - route:
    - destination:
        host: api-service
        subset: production

基于 HTTP 方法的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: method-based-routing
spec:
  hosts:
  - api.example.com
  http:
  # POST requests → Write-only service
  - match:
    - method:
        exact: "POST"
      uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-write-service

  # PUT/PATCH requests → Update service
  - match:
    - method:
        regex: "PUT|PATCH"
      uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-update-service

  # DELETE requests → Delete service
  - match:
    - method:
        exact: "DELETE"
      uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-delete-service

  # GET requests → Read-only service
  - match:
    - method:
        exact: "GET"
      uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-read-service

基于来源的路由

基于 Namespace 的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: source-namespace-routing
  namespace: production
spec:
  hosts:
  - database.production.svc.cluster.local
  http:
  # Requests from production namespace
  - match:
    - sourceNamespace: production
    route:
    - destination:
        host: database
        subset: production

  # Requests from staging namespace
  - match:
    - sourceNamespace: staging
    route:
    - destination:
        host: database
        subset: staging

  # Block other namespaces
  - route:
    - destination:
        host: access-denied

基于 Service Account 的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: source-sa-routing
spec:
  hosts:
  - payment-service
  http:
  # Allow access only from specific Service Account
  - match:
    - sourceLabels:
        app: frontend
        version: v2
    route:
    - destination:
        host: payment-service
        subset: v2

  # Legacy service
  - match:
    - sourceLabels:
        app: frontend
        version: v1
    route:
    - destination:
        host: payment-service
        subset: v1

优先级和回退

匹配规则优先级

Istio 会从上到下评估 VirtualService HTTP 路由规则。

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: priority-example
spec:
  hosts:
  - myapp.example.com
  http:
  # Priority 1: Most specific condition
  - match:
    - uri:
        exact: "/api/v2/users/admin"
      headers:
        x-admin:
          exact: "true"
    route:
    - destination:
        host: admin-api-v2

  # Priority 2: Medium specificity
  - match:
    - uri:
        prefix: "/api/v2/"
    route:
    - destination:
        host: api-v2

  # Priority 3: Less specific
  - match:
    - uri:
        prefix: "/api/"
    route:
    - destination:
        host: api-v1

  # Priority 4 (last): Default fallback
  - route:
    - destination:
        host: frontend

回退策略

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: fallback-strategy
spec:
  hosts:
  - myapp
  http:
  # Requests matching specific conditions
  - match:
    - headers:
        x-canary:
          exact: "true"
    route:
    - destination:
        host: myapp
        subset: canary
    fault:
      abort:
        percentage:
          value: 0
        httpStatus: 503
    # No fallback on canary failure - return error

  # Default requests - with fallback
  - route:
    - destination:
        host: myapp
        subset: stable
      weight: 100

实际示例

示例 1：多租户路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: multi-tenant-routing
spec:
  hosts:
  - api.example.com
  http:
  # Tenant A (identified by header)
  - match:
    - headers:
        x-tenant-id:
          exact: "tenant-a"
    route:
    - destination:
        host: api-service
        subset: tenant-a

  # Tenant B (identified by subdomain)
  - match:
    - authority:
        exact: "tenant-b.api.example.com"
    route:
    - destination:
        host: api-service
        subset: tenant-b

  # Tenant C (identified by path)
  - match:
    - uri:
        prefix: "/tenant-c/"
    rewrite:
      uri: "/"
    route:
    - destination:
        host: api-service
        subset: tenant-c

示例 2：基于功能标志的路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: feature-flag-routing
spec:
  hosts:
  - myapp
  http:
  # Users with new feature enabled
  - match:
    - headers:
        x-feature-new-ui:
          exact: "enabled"
    route:
    - destination:
        host: myapp
        subset: new-ui

  # Beta feature testers
  - match:
    - headers:
        x-feature-beta:
          exact: "enabled"
    route:
    - destination:
        host: myapp
        subset: beta

  # Experimental features (employees only)
  - match:
    - headers:
        x-feature-experimental:
          exact: "enabled"
      sourceLabels:
        role: employee
    route:
    - destination:
        host: myapp
        subset: experimental

  # Default (stable version)
  - route:
    - destination:
        host: myapp
        subset: stable

示例 3：地理路由

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: geo-routing
spec:
  hosts:
  - content.example.com
  http:
  # Korean users
  - match:
    - headers:
        x-country-code:
          exact: "KR"
    route:
    - destination:
        host: content-service
        subset: korea

  # Japanese users
  - match:
    - headers:
        x-country-code:
          exact: "JP"
    route:
    - destination:
        host: content-service
        subset: japan

  # US users
  - match:
    - headers:
        x-country-code:
          exact: "US"
    route:
    - destination:
        host: content-service
        subset: us

  # European users
  - match:
    - headers:
        x-country-code:
          regex: "DE|FR|UK|IT|ES"
    route:
    - destination:
        host: content-service
        subset: europe

  # Other regions (global)
  - route:
    - destination:
        host: content-service
        subset: global

示例 4：API Gateway 模式

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: api-gateway-routing
spec:
  hosts:
  - api.example.com
  gateways:
  - api-gateway
  http:
  # APIs requiring authentication
  - match:
    - uri:
        prefix: "/api/v1/protected/"
      headers:
        authorization:
          regex: "Bearer .*"
    route:
    - destination:
        host: protected-api-service

  # Public APIs
  - match:
    - uri:
        prefix: "/api/v1/public/"
    route:
    - destination:
        host: public-api-service

  # GraphQL endpoint
  - match:
    - uri:
        exact: "/graphql"
      method:
        exact: "POST"
    route:
    - destination:
        host: graphql-service

  # REST API
  - match:
    - uri:
        prefix: "/api/v1/"
    route:
    - destination:
        host: rest-api-service

  # Health check
  - match:
    - uri:
        exact: "/health"
    route:
    - destination:
        host: health-service

  # 404 handling
  - route:
    - destination:
        host: error-service

故障排除

路由未生效

# 1. Check VirtualService status
kubectl get virtualservice -A
kubectl describe virtualservice <name> -n <namespace>

# 2. Check routing rules
istioctl proxy-config routes <pod-name> -n <namespace>

# 3. Check routing to specific service
istioctl proxy-config routes <pod-name> -n <namespace> --name <route-name> -o json

# 4. Validate configuration
istioctl analyze -n <namespace>

调试匹配条件

# Increase Envoy log level
istioctl proxy-config log <pod-name> -n <namespace> --level debug

# Trace requests
kubectl logs -n <namespace> <pod-name> -c istio-proxy -f

# Debug Pilot
kubectl logs -n istio-system -l app=istiod --tail=100

常见问题

1. 匹配顺序问题

# ❌ Wrong order - default route first ignores other rules
http:
- route:  # All traffic goes here
  - destination:
      host: myapp
- match:  # Never executed
  - uri:
      prefix: "/api"
  route:
  - destination:
      host: api-service

# ✅ Correct order
http:
- match:  # Specific rules first
  - uri:
      prefix: "/api"
  route:
  - destination:
      host: api-service
- route:  # Default route last
  - destination:
      host: myapp

2. 正则表达式语法错误

# ❌ Incorrect regex
match:
- uri:
    regex: "/api/v[1-3]"  # Missing anchor

# ✅ Correct regex
match:
- uri:
    regex: "^/api/v[1-3].*"

3. Header 大小写敏感问题

# HTTP headers are case-insensitive
# Istio automatically converts to lowercase
match:
- headers:
    X-Custom-Header:  # Automatically converted to x-custom-header
      exact: "value"

最佳实践

1. 将特定规则放在前面

# ✅ Good example
http:
- match:
  - uri:
      exact: "/api/v2/admin"  # Most specific
  route:
  - destination:
      host: admin-v2
- match:
  - uri:
      prefix: "/api/v2/"  # Medium
  route:
  - destination:
      host: api-v2
- match:
  - uri:
      prefix: "/api/"  # General
  route:
  - destination:
      host: api-v1
- route:  # Default
  - destination:
      host: frontend

2. 尽量减少使用正则表达式

# ❌ Avoid - complex regex degrades performance
match:
- uri:
    regex: "^/(api|admin|public)/v[0-9]+/(users|products|orders)/[a-zA-Z0-9_-]+$"

# ✅ Recommended - use prefix or exact
match:
- uri:
    prefix: "/api/v1/"

3. 清晰命名

# ✅ Use clear names
apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: product-api-routing  # Clear name
  labels:
    app: product-service
    purpose: routing
spec:
  hosts:
  - product-api.example.com

4. 文档

apiVersion: networking.istio.io/v1
kind: VirtualService
metadata:
  name: myapp-routing
  annotations:
    description: "Routes traffic based on API version and user type"
    owner: "platform-team"
spec:
  hosts:
  - myapp.example.com
  http:
  # Route VIP users to dedicated instance
  - match:
    - headers:
        x-user-tier:
          exact: "vip"
    route:
    - destination:
        host: myapp
        subset: vip

5. 测试策略

# Routing rule test script
#!/bin/bash

# API v1 test
curl -H "Host: api.example.com" http://$GATEWAY_URL/api/v1/users

# API v2 test
curl -H "Host: api.example.com" http://$GATEWAY_URL/api/v2/users

# Mobile user test
curl -H "User-Agent: Mobile" http://$GATEWAY_URL/

# Header-based test
curl -H "x-canary: true" http://$GATEWAY_URL/

参考资料

• Istio 流量管理
• VirtualService 参考
• HTTP 路由匹配
• 流量路由