Istio的自定义资源有五十多个，今天先对Network部分的VirtualService的学习做个记录。

介绍

1. 首先献上官方文档：https://istio.io/latest/zh/docs/reference/config/networking/virtual-service/
2. VirtualService主要是定义了服务的路由规则，如果流量满足了我们设定的匹配规则，则会根据我们的设定将流量发送到服务注册表中的服务/版本
3. 样例

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews-route
spec:
	# host为必要字段，表示目标主机，尽量使用FQDN来进行服务引用，同个命名空间可以使用服务的短名称
  hosts:
  - reviews.prod.svc.cluster.local
  # HTTP的有序路由规则列表，对httpx，http2x，grpc，都是有效的，匹配规则从上往下
  http:
  - name: "reviews-v2-routes"
  	# 匹配规则，有根据uri，header，host，port，queryParams，scheme等
  	# 匹配规则有：exact精准匹配，prefix前缀匹配，regex正则匹配
    match:
    - uri:
        exact: "/wpcatalog"
    - uri:
        prefix: "/consumercatalog"
    # 重写HTTP URI和Authority标头。重写将在转发之前执行。
    rewrite:
      uri: "/newcatalog"
    # 重定向，重定向不能与重写一起使用
    redirect:
      uri: /v1/bookRatings
      authority: newratings.default.svc.cluster.local
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v2
      # 权重
      weight: 80
  - name: "reviews-v1-route"
    route:
    - destination:
        host: reviews.prod.svc.cluster.local
        subset: v1
    # cors
    corsPolicy:
      allowOrigin:
      - example.com
      allowMethods:
      - POST
      - GET
      allowCredentials: false
      allowHeaders:
      - X-Foo-Bar
      maxAge: "24h"
        
  # 应用到路由的网关，忽略默认使用默认网关
  gateways:
  - mygateway
  
  # 透传TLS和HTTPS的流量的路由规则列表
  tls:
  - match:
    - port: 443
      sniHosts:
      - login.bookinfo.com
    route:
    - destination:
        host: login.prod.svc.cluster.local  
        
  # 透传tcp流量的有序路由规则列表，对所有HTTP和TLS之外的端口生效      
  tcp:
  - match:
    - port: 27017
    route:
    - destination:
        host: mongo.backup.svc.cluster.local
        port:
          number: 5555

演示

创建两个对应的http server

• httpd：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: httpd
  labels:
    server: httpd
    app: web
spec:
  replicas: 1
  selector:
    matchLabels:
      server: httpd
      app: web
  template:
    metadata:
      labels:
        server: httpd
        app: web
    spec:
      containers:
      - name: busybox
        image: busybox
        imagePullPolicy: IfNotPresent
        command: ["/bin/sh", "-c", "echo 'this is httpd' > /var/www/index.html; httpd -f -p 8080 -h /var/www"]

---
apiVersion: v1
kind: Service
metadata:
  name: httpd-svc
spec:
  selector:
    server: httpd
  ports:
  - name: http
    port: 8080
    targetPort: 8080
    protocol: TCP

• tomcat

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat
  labels:
    server: tomcat
    app: web
spec:
  replicas: 1
  selector:
    matchLabels:
      server: tomcat
      app: web
  template:
    metadata:
      labels:
        server: tomcat
        app: web
    spec:
      containers:
      - name: tomcat
        image: docker.io/kubeguide/tomcat-app:v1
        imagePullPolicy: IfNotPresent
        
--- 
apiVersion: v1
kind: Service
metadata:
  name: tomcat-svc
spec:
  selector:
    server: tomcat
  ports:
  - name: http
    port: 8080
    targetPort: 8080
    protocol: TCP

• Busy box进入容器中测试

   apiVersion: apps/v1
   kind: Deployment
   metadata:
     name: hexiaohong-client
   spec:
     replicas: 1
     selector:
       matchLabels:
         app: hexiaohong-client
     template:
       metadata:
         labels:
           app: hexiaohong-client
       spec:
         containers:
         - name: busybox
           image: busybox
           imagePullPolicy: IfNotPresent
           command: ["/bin/sh", "-c", "sleep 3600"]    
--- 
   apiVersion: v1
   kind: Service
   metadata:
     name: web-svc
   spec:
     selector:
       app: hexiaohong-client
     ports:
     - name: http
       port: 8080
       targetPort: 8080
       protocol: TCP

进入busybox测试

• httpd

• tomcat

创建VirtualService实现流控

创建VirtualService

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: web-svc-vs
spec:
  hosts:
  - web-svc.default.svc.cluster.local
  http:
  - route:
    - destination:
        host: httpd-svc
      weight: 80
    - destination:
        host: tomcat-svc
      weight: 20

查看VirtualService：

   # kubectl get virtualservices.networking.istio.io
   
   NAME         GATEWAYS               HOSTS                                   AGE
   bookinfo     ["bookinfo-gateway"]   ["*"]                                   31h
   web-svc-vs                          ["web-svc.default.svc.cluster.local"]   43s

80%流量到httpd，20%到tomcat

创建VirtualService实现路由

1. 创建带匹配条件的VirtualService

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: web-svc-vs
spec:
  hosts:
  - web-svc.default.svc.cluster.local
  http:
  - match:
    - headers:
        to:
          exact: httpd
    route:
    - destination:
        host: httpd-svc
  - route:
    - destination:
        host: tomcat-svc

携带header:'to: httpd'将流量导入httpd，否则则到tomcat

样例来自学习九析大佬的教程