Kubernetes中的Ingress

Ingress是什么

Ingress ：简单理解就是个规则定义；比如说某个域名对应某个 service，即当某个域名的请求进来时转发给某个 service;这个规则将与 Ingress Controller 结合，然后 Ingress Controller 将其动态写入到负载均衡器配置中，从而实现整体的服务发现和负载均衡

Ingress Controller

实质上可以理解为是个监视器，Ingress Controller 通过不断地跟 kubernetes API 打交道，实时的感知后端 service、pod 等变化，比如新增和减少 pod，service 增加与减少等；当得到这些变化信息后，Ingress Controller 再结合Ingress 生成配置，然后更新反向代理负载均衡器，并刷新其配置，达到服务发现的作用

安装Ingress

kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/mandatory.yaml #安装ingress-Controller

• 创建一后端pod service：

  [root@master ingress]# kubectl apply -f deploy-demo.yaml
  [root@master ingress]# cat deploy-demo.yaml 
  apiVersion: v1
  kind: Service
  metadata:
    name: myapp
    namespace: default
  spec:
    selector:
      app: myapp
      release: canary
    ports:
    - name: http
      targetPort: 80
      port: 80
  
  ---
  apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: myapp-deploy
    namespace: default
  spec:
    replicas: 3
    selector:
      matchLabels:
        app: myapp
        release: canary
    template:
      metadata:
        labels:
          app: myapp
          release: canary
      spec:
        containers:
        - name: myapp
          image: ikubernetes/myapp:v2
          ports:
          - name: http
            containerPort: 80
  

• 创建一个用于暴露端口的service

  [root@master baremetal]# kubectl apply -f service-nodeport.yaml
  [root@master baremetal]# cat service-nodeport.yaml 
  apiVersion: v1
  kind: Service
  metadata:
    name: ingress-nginx
    namespace: ingress-nginx
    labels:
      app.kubernetes.io/name: ingress-nginx
      app.kubernetes.io/part-of: ingress-nginx
  spec:
    type: NodePort
    ports:
      - name: http
        port: 80
        targetPort: 80
        protocol: TCP
        nodePort: 30080
      - name: https
        port: 443
        targetPort: 443
        protocol: TCP
        nodePort: 30443
    selector:
      app.kubernetes.io/name: ingress-nginx
  

• 创建Ingress文件

  [root@master ingress]# kubectl apply -f ingress-myapp.yaml
  [root@master ingress]# cat ingress-myapp.yaml 
  apiVersion: extensions/v1beta1
  kind: Ingress
  metadata:
    name: ingress-myapp
    namespace: default
    annotations:
      kubernetes.io/ingress.class: "nginx"
  spec:
    rules:
    - host: myapp.template.com
      http:
        paths:
        - path:
          backend:
            serviceName: myapp
            servicePort: 80

• 查看信息

  [root@master ingress]# kubectl get ingress
  NAME                 HOSTS                 ADDRESS   PORTS     AGE
  ingress-myapp        myapp.template.com              80        5h55
  [root@master ingress]# kubectl get svc
  NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)             AGE
  myapp        ClusterIP   10.98.30.144     <none>        80/TCP              4h7m
  [root@master ingress]# kubectl get pods
  NAME                             READY   STATUS    RESTARTS   AGE
  myapp-deploy-7b64976db9-lfnlv    1/1     Running   0          6h30m
  myapp-deploy-7b64976db9-nrfgs    1/1     Running   0          6h30m
  myapp-deploy-7b64976db9-pbqvh    1/1     Running   0          6h30m
  #访问
  [root@master ingress]# curl myapp.template.com:30080
  Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

Ingress使用ssl

[root@master ingress]# cat tomcat-deploy.yaml 
apiVersion: v1
kind: Service
metadata:
  name: tomcat
  namespace: default
spec:
  selector:
    app: tomcat
    release: canary
  ports:
  - name: http
    targetPort: 8080
    port: 8080
  - name: ajp
    targetPort: 8009
    port: 8009
    
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deploy
  namespace: default
spec:
  replicas: 3
  selector:
    matchLabels:
      app: tomcat
      release: canary
  template:
    metadata:
      labels:
        app: tomcat
        release: canary
    spec:
      containers:
      - name: tomcat
        image: tomcat:8.5-alpine
        ports:
        - name: http
          containerPort: 8080
        - name: ajp
          containerPort: 8009
[root@master ingress]# kubectl apply -f  tomcat-deploy.yaml 

[root@master ingress]# openssl genrsa -out tls.key 2048
[root@master ingress]# openssl req -new -x509 -key tls.key -out tls.crt -subj /C=CN/ST=Beijing/L=Beijing/O=DevOps/CN=tomcat.template.com
[root@master ingress]# kubectl create secret tls tomcat-ingress-secret --cert=tls.crt --key=tls.key
[root@master ingress]# kubectl get secret
NAME                    TYPE                                  DATA   AGE
default-token-962mh     kubernetes.io/service-account-token   3      32h
tomcat-ingress-secret   kubernetes.io/tls                     2      66m

[root@master ingress]# cat ingress-tomcat-tls.yaml 
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-tomcat-tls
  namespace: default
  annotations:
    kubernetes.io/ingress.class: "nginx"
spec:
  tls:
  - hosts:
      - tomcat.template.com
    secretName: tomcat-ingress-secret
  rules:
  - host: tomcat.template.com
    http:
      paths:
      - path:
        backend:
          serviceName: tomcat
          servicePort: 8080
[root@master ingress]# kubectl apply -f ingress-tomcat-tls.yaml

[root@master ingress]# curl -k https://tomcat.template.com:30443 #测试访问