K8S ingress

这里使用的版本为 K8S v1.16.9, nginx-0.30.0

简单介绍 Ingress 主要有两个部分组成 (ingress与ingress-controller)

ingress: 指的是k8s中的一个api对象，一般用yaml配置。作用是定义请求如何转发到service的规则，可以理解为配置模板。
ingress-controller: 具体实现反向代理及负载均衡的程序，对ingress定义的规则进行解析，根据配置的规则来实现请求转发。

简单来说，ingress-controller才是负责具体转发的组件 pod，如：nginx-ingress-controller，通过各种方式将它暴露在集群入口，外部对集群的请求流量会先到ingress-controller，而ingress对象是用来告诉ingress-controller该如何转发请求，比如哪些域名哪些path要转发到哪些服务等等。

下面我们创建一个例子

创建一个后端服务

mkdir -p /data/ingress && cd /data/ingress
cat myapp-deploy.yaml 

apiVersion: v1
kind: Service
metadata:
  name: myapp
  namespace: default
spec:
  selector:
    release: canary
  ports:
  - name: http
    targetPort: 80
    port: 80
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: myapp-deploy
  namespace: default
spec:
  replicas: 1
  selector:
    matchLabels:
      release: canary
  template:
    metadata:
      labels:
        release: canary
    spec:
      containers:
      - name: myapp
        image: ikubernetes/myapp:v2
        ports:
        - name: http
          containerPort: 80

kubectl apply -f myapp-deploy.yaml 

# 测试 svc 
[root@k8s-master01 ingress]# kubectl get svc
NAME         TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.96.0.1       <none>        443/TCP   4h3m
myapp        ClusterIP   10.105.84.255   <none>        80/TCP    24m

[root@k8s-master01 ingress]# curl 10.105.84.255
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

创建一个 ingress-controller

cd /data/ingress
wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml

kubectl apply -f mandatory.yaml

# 检查
kubectl get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx --watch

创建 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.klvchen.com
    http:
      paths:
      - path:
        backend:
          serviceName: myapp
          servicePort: 80

kubectl apply -f ingress-myapp.yaml

# 因为 ingress 对象是用来告诉 ingress-controller 该如何转发请求，对于 nginx 来说就是如何配置 nginx.conf
kubectl get pod -n ingress-nginx -o wide
NAME                                        READY   STATUS    RESTARTS   AGE   IP            NODE           NOMINATED NODE   READINESS GATES
nginx-ingress-controller-7f74f657bd-wbknh   1/1     Running   0          35m   10.244.0.10   k8s-master01   <none>           <none>

# 测试 nginx-ingress-controller 是否加入 ingress 的配置
# 在 /etc/hosts 中加入配置
vi /etc/hosts
10.244.0.10 myapp.klvchen.com

curl myapp.klvchen.com
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

# nginx-ingress-controller 已经成功加入 ingress 配置

创建一个 svc，给 ingress-controller 接入流量

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
    app.kubernetes.io/part-of: ingress-nginx
  externalTrafficPolicy: Cluster

kubectl apply -f service-nodeport.yaml 

# 测试
# 在 /etc/hosts 中加入配置宿主机的IP
vi /etc/hosts
172.18.54.75 myapp.klvchen.com

curl myapp.klvchen.com:30080
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

这个时候，你只需在宿主机安装一个 nginx，把请求转入到两个端口 30080 和 30443 就可以按域名管理所有的 svc了。

cat test.yanpin.cn.conf 
server {
    listen      80;
    server_name *.test.klvchen.com;


    location /
    {
        proxy_pass   http://172.18.54.75:30080;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For  $proxy_add_x_forwarded_for;
    }

    access_log  logs/test.klvchen.com.access.log main;
    error_log   logs/test.klvchen.com.error.log;
}

参考

https://github.com/kubernetes/ingress-nginx/blob/nginx-0.30.0/docs/deploy/index.md