kubernetes-ingress（十）

ingress

https://kubernetes.io/docs/concepts/services-networking/ingress/

pod与ingress的关系

•通过label-selector相关联
•通过Ingress Controller实现Pod的负载均衡
-支持TCP/UDP 4层和HTTP 7层

kubernetes-ingress（十）

Ingress 组成？

ingress controller：将新加入的Ingress转化成Nginx的配置文件并使之生效
ingress服务：将Nginx的配置抽象成一个Ingress对象，每添加一个新的服务只需写一个新的Ingress的yaml文件即可

Ingress 工作原理?

ingress controller通过和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，
再写到nginx-ingress-control的pod里，这个Ingress controller的pod里运行着一个Nginx服务，控制器会把生成的nginx配置写入/etc/nginx.conf文件中，
然后reload一下使配置生效。
以此达到域名分配置和动态更新的问题。

kubernetes-ingress（十）

ingress部署文档

https://github.com/kubernetes/ingress-nginx/blob/master/docs/deploy/index.md

下载yaml文件，修改使用宿主机网络 hostNetwork: true

[root@k8s-master1 ingress]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/master/deploy/mandatory.yaml
[root@k8s-master1 ingress]# kubectl apply -f mandatory.yaml 
namespace/ingress-nginx created
configmap/nginx-configuration created
configmap/tcp-services created
configmap/udp-services created
serviceaccount/nginx-ingress-serviceaccount created
clusterrole.rbac.authorization.k8s.io/nginx-ingress-clusterrole created
role.rbac.authorization.k8s.io/nginx-ingress-role created
rolebinding.rbac.authorization.k8s.io/nginx-ingress-role-nisa-binding created
clusterrolebinding.rbac.authorization.k8s.io/nginx-ingress-clusterrole-nisa-binding created
deployment.extensions/nginx-ingress-controller created

查看ingress部署的node节点，使用宿主机网络会在node监听80和443端口

[root@k8s-master1 ingress]# kubectl get ns
NAME            STATUS   AGE
default         Active   6d20h
ingress-nginx   Active   27m
kube-public     Active   6d20h
kube-system     Active   6d20h
[root@k8s-master1 ingress]# kubectl get pods -n ingress-nginx -o wide
NAME                                        READY   STATUS    RESTARTS   AGE   IP              NODE            NOMINATED NODE   READINESS GATES
nginx-ingress-controller-5c98c674b8-l9ft2   1/1     Running   0          28m   192.168.0.125   192.168.0.125   <none>           <none>

[root@k8s-node01 ~]# netstat -tnlp |egrep "80|443"          
tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      2358/nginx: master  
tcp        0      0 0.0.0.0:443             0.0.0.0:*               LISTEN      2358/nginx: master  
tcp        0      0 0.0.0.0:18080           0.0.0.0:*               LISTEN      2358/nginx: master  
tcp6       0      0 :::80                   :::*                    LISTEN      2358/nginx: master  
tcp6       0      0 :::443                  :::*                    LISTEN      2358/nginx: master  
tcp6       0      0 :::18080                :::*                    LISTEN      2358/nginx: master

准备后端服务

[root@k8s-master1 ingress]# cat deploy-demo.yaml
#创建service为myapp
apiVersion: v1
kind: Service
metadata:
  name: myapp
  namespace: default
spec:
  selector:
    app: myapp
    release: canary
  ports:
  - name: http
    targetPort: 80
    port: 80

---
#创建后端服务的deployment
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-backend-pod
  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

[root@k8s-master1 ingress]# kubectl apply -f deploy-demo.yaml 
service/myapp created
deployment.apps/myapp-backend-pod created
[root@k8s-master1 ingress]# kubectl get pod,svc
NAME                                     READY   STATUS    RESTARTS   AGE
pod/myapp-backend-pod-6b56d98b6b-27vvs   1/1     Running   0          12s
pod/myapp-backend-pod-6b56d98b6b-6rq8w   1/1     Running   0          12s
pod/myapp-backend-pod-6b56d98b6b-ndbm6   1/1     Running   0          12s

NAME                 TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
service/kubernetes   ClusterIP   10.0.0.1     <none>        443/TCP   6d21h
service/myapp        ClusterIP   10.0.0.79    <none>        80/TCP    12s

[root@k8s-node01 ~]# curl 10.0.0.79
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

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