Ingress

官方文档网址：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

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。

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>

配置ingress规则

[root@k8s-master1 ingress]# vim ingress-myapp.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: simple-fanout-example
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
  - host: foo.bar.com
    http:
      paths:
      - path: /
        backend:
          serviceName: myapp
          servicePort: 80

[root@k8s-master1 ingress]# kubectl apply -f ingress-myapp.yaml 
ingress.extensions/simple-fanout-example created
[root@k8s-master1 ingress]# kubectl get ingress
NAME                    HOSTS         ADDRESS   PORTS   AGE
simple-fanout-example   foo.bar.com             80      10s

设置域名解析到ip，即可访问域名

[root@k8s-master1 ingress]# curl foo.bar.com
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

查看详细信息

[root@k8s-master1 ingress]# kubectl describe ingress simple-fanout-example
Name:             simple-fanout-example
Namespace:        default
Address:          
Default backend:  default-http-backend:80 (<none>)
Rules:
  Host         Path  Backends
  ----         ----  --------
  foo.bar.com  
               /   myapp:80 (<none>)
Annotations:
  kubectl.kubernetes.io/last-applied-configuration:  {"apiVersion":"extensions/v1beta1","kind":"Ingress","metadata":{"annotations":{"nginx.ingress.kubernetes.io/rewrite-target":"/"},"name":"simple-fanout-example","namespace":"default"},"spec":{"rules":[{"host":"foo.bar.com","http":{"paths":[{"backend":{"serviceName":"myapp","servicePort":80},"path":"/"}]}}]}}

  nginx.ingress.kubernetes.io/rewrite-target:  /
Events:
  Type    Reason  Age    From                      Message
  ----    ------  ----   ----                      -------
  Normal  CREATE  3m58s  nginx-ingress-controller  Ingress default/simple-fanout-example

进入nginx-ingress-controller进行查看是否注入了nginx的配置

[root@k8s-master1 ingress]# kubectl get pod -n ingress-nginx
NAME                                        READY   STATUS    RESTARTS   AGE
nginx-ingress-controller-5c98c674b8-l9ft2   1/1     Running   0          67m
[root@k8s-master1 ingress]# kubectl exec -n ingress-nginx -it nginx-ingress-controller-5c98c674b8-l9ft2 bash
www-data@k8s-node01:/etc/nginx$ cat nginx.conf
........
    ## start server foo.bar.com
    server {
        server_name foo.bar.com ;
        
        listen 80;
        
        listen [::]:80;
        
        set $proxy_upstream_name "-";
        
        location / {
            
            set $namespace      "default";
            set $ingress_name   "simple-fanout-example";
            set $service_name   "myapp";
            set $service_port   "80";
            set $location_path  "/";
            
            rewrite_by_lua_block {
                balancer.rewrite()
            }
            access_by_lua_block {
                
            }
            header_filter_by_lua_block {
                
            }

构建TLS站点

准备证书

[root@k8s-master1 ingress]# openssl genrsa -out tls.key 2048
Generating RSA private key, 2048 bit long modulus
..................................................................................+++
........................+++
e is 65537 (0x10001)
[root@k8s-master1 ingress]# openssl req -new -x509 -key tls.key -out tls.crt -subj /C=CN/ST=Beijing/L=Beijing/O=DevOps/CN=sslexample.foo.com

创建secret

[root@k8s-master1 ingress]# kubectl create secret tls sslexample-foo-com --cert=tls.crt --key=tls.key 
secret/sslexample-foo-com created
[root@k8s-master1 ingress]# kubectl get secret
NAME                   TYPE                                  DATA   AGE
default-token-7vs6s    kubernetes.io/service-account-token   3      6d22h
registry-pull-secret   kubernetes.io/dockerconfigjson        1      5d1h
sslexample-foo-com     kubernetes.io/tls                     2      28s
[root@k8s-master1 ingress]# kubectl describe secret sslexample-foo-com
Name:         sslexample-foo-com
Namespace:    default
Labels:       <none>
Annotations:  <none>

Type:  kubernetes.io/tls

Data
====
tls.crt:  1298 bytes
tls.key:  1675 bytes

创建ingress

[root@k8s-master1 ingress]# vim ingress-https.yaml 

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: tls-example-ingress
spec:
  tls:
  - hosts:
    - sslexample.foo.com
    secretName: sslexample-foo-com
  rules:
    - host: sslexample.foo.com
      http:
        paths:
        - path: /
          backend:
            serviceName: myapp
            servicePort: 80

[root@k8s-master1 ingress]# kubectl apply -f ingress-https.yaml
ingress.extensions/tls-example-ingress created
[root@k8s-master1 ingress]# kubectl get ingress
NAME                    HOSTS                ADDRESS   PORTS     AGE
simple-fanout-example   foo.bar.com                    80        59m
tls-example-ingress     sslexample.foo.com             80, 443   29s

[root@k8s-master1 ingress]# kubectl describe ingress tls-example-ingress
Name:             tls-example-ingress
Namespace:        default
Address:          
Default backend:  default-http-backend:80 (<none>)
TLS:
  sslexample-foo-com terminates sslexample.foo.com
Rules:
  Host                Path  Backends
  ----                ----  --------
  sslexample.foo.com  
                      /   myapp:80 (<none>)
Annotations:
  kubectl.kubernetes.io/last-applied-configuration:  {"apiVersion":"extensions/v1beta1","kind":"Ingress","metadata":{"annotations":{},"name":"tls-example-ingress","namespace":"default"},"spec":{"rules":[{"host":"sslexample.foo.com","http":{"paths":[{"backend":{"serviceName":"myapp","servicePort":80},"path":"/"}]}}],"tls":[{"hosts":["sslexample.foo.com"],"secretName":"sslexample-foo-com"}]}}

Events:
  Type    Reason  Age   From                      Message
  ----    ------  ----  ----                      -------
  Normal  CREATE  72s   nginx-ingress-controller  Ingress default/tls-example-ingress

访问测试

成功！