Ingress详解
Ingress
Service对集群外暴露端口两种方式，这两种方式都有一定的缺点：
NodePort：会占用集群集群端口，当集群服务变多时，缺点明显LoadBalancer：每个Service都需要一个LB，并且需要k8s之外设备支持
基于现状，k8s提供了Ingress资源对象,Ingresss只需要一个NodePort或一个LB就能满足多个Service的需求。
可以在Ingress建立规则，Ingress Controller通过监听这些配置规则并转化成Nignx反向代理配置，对外提供服务。
核心概念：
ingress：k8s对象，作用定义请求如何转发service规则ingress controller：具体实现反向代理及负载均衡的程序,对ingress汇总进行解析，根据规则实现请求转发
工作原理：
- 编写Ingress规则，说明域名对应k8s集群中那个Service
- Ingress控制器动态感知Ingress服务规则变化，然后生成一段对应Nginx反向代理配置
- Ingress控制器将生成Nginx配置写入运行的Nginx服务中，并动态更新
环境准备
搭建Ingress环境
#创建文件夹
[root@master ~]# mkdir ingress-controller
[root@master ~]# cd ingress-controller/
#获取资源 （需要科学上网）也可以github直接下载再上传上去
[root@master ingress-controller]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml
[root@master ingress-controller]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/provider/baremetal/service-nodeport.yaml[root@master ingress-controller]# ls
mandatory.yaml service-nodeport.yaml
# 修改mandatory.yaml文件中的仓库
# 修改quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.30.0
# 为quay-mirror.qiniu.com/kubernetes-ingress-controller/nginx-ingress-controller:0.30.0#创建ingress-nginx
[root@master ingress-controller]# kubectl apply -f ./
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.apps/nginx-ingress-controller created
limitrange/ingress-nginx created
service/ingress-nginx created#查看Pod
[root@master ingress-controller]# kubectl get pod -n ingress-nginx
NAME READY STATUS RESTARTS AGE
nginx-ingress-controller-7f74f657bd-rjpgn 1/1 Running 0 81s
#查看Service
[root@master ingress-controller]# kubectl get svc -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx NodePort 10.109.45.51 <none> 80:30291/TCP,443:30946/TCP 2m15s
准备Service和Pod
创建tomcat-nginx.yaml
apiVersion: apps/v1
kind: Deployment
metadata:name: nginx-deploymentnamespace: dev
spec:replicas: 3selector:matchLabels:app: nginx-podtemplate:metadata:labels:app: nginx-podspec:containers:- name: nginximage: nginx:1.17.1ports:- containerPort: 80---apiVersion: apps/v1
kind: Deployment
metadata:name: tomcat-deploymentnamespace: dev
spec:replicas: 3selector:matchLabels:app: tomcat-podtemplate:metadata:labels:app: tomcat-podspec:containers:- name: tomcatimage: tomcat:8.5-jre10-slimports:- containerPort: 8080---apiVersion: v1
kind: Service
metadata:name: nginx-servicenamespace: dev
spec:selector:app: nginx-podclusterIP: Nonetype: ClusterIPports:- port: 80targetPort: 80---apiVersion: v1
kind: Service
metadata:name: tomcat-servicenamespace: dev
spec:selector:app: tomcat-podclusterIP: Nonetype: ClusterIPports:- port: 8080targetPort: 8080
#创建名称空间
[root@master tmp]# kubectl create ns dev
namespace/dev created
[root@master tmp]# vim tomcat-nginx.yaml
#创建svc和pod
[root@master tmp]# kubectl create -f tomcat-nginx.yaml
deployment.apps/nginx-deployment created
deployment.apps/tomcat-deployment created
service/nginx-service created
service/tomcat-service created
[root@master tmp]# kubectl get svc -n dev
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx-service ClusterIP None <none> 80/TCP 8s
tomcat-service ClusterIP None <none> 8080/TCP 8sHTTP代理
创建ingress-http.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:name: ingress-httpnamespace: dev
spec:rules:- host: nginx.rkun18.comhttp:paths:- path: /backend:serviceName: nginx-serviceservicePort: 80 - host: tomcat.rkun18.comhttp:paths:- path: /backend:serviceName: tomcat-serviceservicePort: 8080
配置两个对应的规则
[root@master tmp]# vim ingress-http.yaml
[root@master tmp]# kubectl create -f ingress-http.yaml
ingress.extensions/ingress-http created
[root@master tmp]# kubectl get ing -n dev
NAME HOSTS ADDRESS PORTS AGE
ingress-http nginx.rkun18.com,tomcat.rkun18.com 80 9s[root@master tmp]# kubectl describe ing ingress-http -n dev
Name: ingress-http
Namespace: dev
Address: 10.109.45.51
Default backend: default-http-backend:80 (<none>)
Rules:Host Path Backends---- ---- --------nginx.rkun18.com/ nginx-service:80 (10.244.1.10:80,10.244.1.9:80,10.244.2.6:80)tomcat.rkun18.com/ tomcat-service:8080 (10.244.1.11:8080,10.244.2.7:8080,10.244.2.8:8080)
Annotations:
Events:Type Reason Age From Message---- ------ ---- ---- -------Normal CREATE 59s nginx-ingress-controller Ingress dev/ingress-httpNormal UPDATE 0s nginx-ingress-controller Ingress dev/ingress-http由于无法解析地址，仅作测试使用，我们需要更改主机hosts文件：
将你的master主机IP和你设置的域名进行绑定
你的master节点IP nginx.rkun18.com
你的master节点IP tomcat.rkun18.com
#查看ingress对外暴露的端口
[root@master tmp]# kubectl get svc -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx NodePort 10.109.45.51 <none> 80:30291/TCP,443:30946/TCP 28mHTTPS代理
创建证书
[root@master ~]# openssl req -x509 -sha256 -nodes -days 365 -newkey rsa:2048 -keyout tls.key -out tls.crt -subj "/C=CN/ST=BJ/L=BJ/O=nginx/CN=rkun18.com"
Generating a 2048 bit RSA private key
.............+++
.............................................................................+++
writing new private key to 'tls.key'
-----
#创建密钥
[root@master ~]# kubectl create secret tls tls-secret --key tls.key --cert tls.crt
secret/tls-secret created
[root@master ~]#创建ingress-https.yaml
apiVersion: extensions/v1beta1
kind: Ingress
metadata:name: ingress-httpsnamespace: dev
spec:tls:- hosts:- nginx.rkun18.com- tomcat.rkun18.comsecretName: tls-secret # 指定秘钥rules:- host: nginx.rkun18.comhttp:paths:- path: /backend:serviceName: nginx-serviceservicePort: 80- host: tomcat.rkun18.comhttp:paths:- path: /backend:serviceName: tomcat-serviceservicePort: 8080
[root@master tmp]# kubectl create -f ingress-https.yaml
ingress.extensions/ingress-https created
[root@master tmp]# kubectl get ing ingress-https -n dev
NAME HOSTS ADDRESS PORTS AGE
ingress-https nginx.rkun18.com,tomcat.rkun18.com 10.109.45.51 80, 443 23s访问第二个端口30946
[root@master tmp]# kubectl get svc -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx NodePort 10.109.45.51 <none> 80:30291/TCP,443:30946/TCP 110m