Pod & Service

Pod与Service的关系：

1. 通过lable-selector关联
2. service实现pod的负载均衡（TCP/UDP ）

Service 3种常用类型

1. ClusterIP ： 集群内部使用
2. NodePort : 对外暴露应用
3. LoadBalancer : 适用公有云，对外暴露应用

apiVersion: v1
kind: Service
metadata:
  labels:
    app: web
  name: web
spec:
  type: ClusterIP
  ports:
  - port: 8080
    protocol: TCP
    targetPort: 80
  selector:
    app: web

Ingress Controller :

项目地址：https://github.com/kubernetes/ingress-nginx

wget  https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-v0.46.0/deploy/static/provider/cloud/deploy.yaml

修改如下部分

Ingress Contronler怎么工作的？
Ingress Contronler通过与Kubernetes API 交互，动态的去感知集群中Ingress 规则变化，然后读取它，按照自定义的规则，规则就是写明了哪个域名对应哪个service，生成一段Nginx 配置，应用到管理的Nginx服务，然后热加载生效。
以此来达到Nginx负载均衡器配置及动态更新的问题。

流程包流程：客户端->Ingress Controller（nginx）-> 分布在各节点Pod

案例：

1. 先部署deployment，创建pod

apiVersion: apps/v1
kind: Deployment
metadata:
  name: web
spec:
  replicas: 1
  selector:
    matchLabels:
      app: web
  template:
    metadata:
      labels:
        app: web
    spec:
      containers:
      - image: nginx:1.17
        name: nginx

2. 对pod创建service

apiVersion: v1
kind: Service
metadata:
  name: web
  namespace: default
spec:
  ports:
  - port: 80
    protocol: TCP
    targetPort: 8080
  selector:
    app: web
  type: NodePort

3. 创建ingress绑定service

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: alinagedu
spec:
  rules:
  - host: web.aliangedu.cn
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: web
            port:
              number: 80

4. 检查

[root@master yaml]# kubectl get pod  -o wide
NAME                   READY   STATUS    RESTARTS   AGE   IP               NODE    NOMINATED NODE   READINESS GATES
web-6bc4dfc596-94xdj   1/1     Running   0          43h   10.244.104.52    node2   <none>           <none>
web-6bc4dfc596-mgdjw   1/1     Running   0          43h   10.244.166.153   node1   <none>           <none>

[root@master yaml]# kubectl get svc,ep
NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP   3d23h
service/web          ClusterIP   10.104.105.213   <none>        80/TCP    43h

NAME                   ENDPOINTS                            AGE
endpoints/kubernetes   172.16.10.60:6443                    3d23h
endpoints/web          10.244.104.52:80,10.244.166.153:80   43h

[root@master yaml]# kubectl get ingress
NAME        CLASS    HOSTS              ADDRESS   PORTS   AGE
alinagedu   <none>   web.aliangedu.cn             80      42h

5. 测试

[root@localhost ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
172.16.10.110 csdharbor.com
172.16.10.62 web.aliangedu.cn

[root@localhost ~]# curl web.aliangedu.cn
myapp-v2
[root@localhost ~]# curl web.aliangedu.cn
myapp-v2
[root@localhost ~]# curl web.aliangedu.cn
myapp-v1
[root@localhost ~]# curl web.aliangedu.cn
myapp-v2