前言
- 本篇来学习Ingress
Ingress介绍
在前面课程中已经提到，Service对集群之外暴露服务的主要方式有两种：NotePort和LoadBalancer，但是这两种方式，都有一定的缺点：
- NodePort方式的缺点是会占用很多集群机器的端口，那么当集群服务变多的时候，这个缺点就愈发明显
- LB方式的缺点是每个service需要一个LB，浪费、麻烦，并且需要kubernetes之外设备的支持
基于这种现状，kubernetes提供了Ingress资源对象，Ingress只需要一个NodePort或者一个LB就可以满足暴露多个Service的需求。工作机制大致如下图表示：
实际上，Ingress相当于一个7层的负载均衡器，是kubernetes对反向代理的一个抽象，它的工作原理类似于Nginx，可以理解成在Ingress里建立诸多映射规则，Ingress Controller通过监听这些配置规则并转化成Nginx的反向代理配置 , 然后对外部提供服务。在这里有两个核心概念：
- ingress：kubernetes中的一个对象，作用是定义请求如何转发到service的规则
- 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，实现方式有很多，比如Nginx, Contour, Haproxy等等
Ingress（以Nginx为例）的工作原理如下：
- 用户编写Ingress规则，说明哪个域名对应kubernetes集群中的哪个Service
- Ingress控制器动态感知Ingress服务规则的变化，然后生成一段对应的Nginx反向代理配置
- Ingress控制器会将生成的Nginx配置写入到一个运行着的Nginx服务中，并动态更新
- 到此为止，其实真正在工作的就是一个Nginx了，内部配置了用户定义的请求转发规则
Ingress使用
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ingress-nginx，本次案例使用的是0.30版本 [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 # 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ingress-nginx [root@master ingress-controller]# kubectl get pod -n ingress-nginx NAME READY STATUS RESTARTS AGE nginx-ingress-controller-56fc46bbfc-tgts6 0/1 ImagePullBackOff 0 9s # 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 10.110.59.157 <none> 80:30073/TCP,443:30254/TCP 34s
准备service和pod
- 为了后面的实验比较方便，创建如下图所示的模型
- 创建tomcat-nginx.yaml
apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deployment namespace: dev spec: replicas: 3 selector: matchLabels: app: nginx-pod template: metadata: labels: app: nginx-pod spec: containers: - name: nginx image: nginx:1.17.1 ports: - containerPort: 80 --- apiVersion: apps/v1 kind: Deployment metadata: name: tomcat-deployment namespace: dev spec: replicas: 3 selector: matchLabels: app: tomcat-pod template: metadata: labels: app: tomcat-pod spec: containers: - name: tomcat image: tomcat:8.5-jre10-slim ports: - containerPort: 8080 --- apiVersion: v1 kind: Service metadata: name: nginx-service namespace: dev spec: selector: app: nginx-pod clusterIP: None type: ClusterIP ports: - port: 80 targetPort: 80 --- apiVersion: v1 kind: Service metadata: name: tomcat-service namespace: dev spec: selector: app: tomcat-pod clusterIP: None type: ClusterIP ports: - port: 8080 targetPort: 8080
# 创建 [root@master ~]# kubectl create -f tomcat-nginx.yaml deployment.apps/nginx-deployment created deployment.apps/tomcat-deployment created service/nginx-service created service/tomcat-service created # 查看 [root@master ~]# 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 8s
Http代理
- 创建ingress-http.yaml
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: ingress-http namespace: dev spec: rules: - host: nginx.itheima.com http: paths: - path: / backend: serviceName: nginx-service servicePort: 80 - host: tomcat.itheima.com http: paths: - path: / backend: serviceName: tomcat-service servicePort: 8080
# 创建 [root@master ~]# kubectl create -f ingress-http.yaml ingress.extensions/ingress-http created # 查看 [root@master ~]# kubectl get ing ingress-http -n dev NAME HOSTS ADDRESS PORTS AGE ingress-http nginx.itheima.com,tomcat.itheima.com 80 10s # 查看详情 [root@master ~]# kubectl describe ing ingress-http -n dev Name: ingress-http Namespace: dev Address: Default backend: default-http-backend:80 (<none>) Rules: Host Path Backends ---- ---- -------- nginx.itheima.com / nginx-service:80 (10.244.2.54:80,10.244.2.56:80,10.244.2.57:80 + 3 more...) tomcat.itheima.com / tomcat-service:8080 (10.244.2.55:8080,10.244.3.67:8080,10.244.3.68:8080) Annotations: Events: <none> # 查看service [root@master ~]# kubectl get svc -n ingress-nginx NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE ingress-nginx NodePort 10.110.59.157 <none> 80:30073/TCP,443:30254/TCP 91m # 接下来,在本地电脑上配置host文件,解析上面的两个域名到192.168.109.100(master)上 # 然后,就可以分别访问tomcat.itheima.com:30073和 nginx.itheima.com:30073查看效果了 （端口为上面service对应的端口）
Https代理
- 创建证书
# 生成证书 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=itheima.com" # 创建密钥 kubectl create secret tls tls-secret --key tls.key --cert tls.crt
- 创建ingress-https.yaml
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: ingress-https namespace: dev spec: tls: - hosts: - nginx.itheima.com - tomcat.itheima.com secretName: tls-secret # 指定秘钥 rules: - host: nginx.itheima.com http: paths: - path: / backend: serviceName: nginx-service servicePort: 80 - host: tomcat.itheima.com http: paths: - path: / backend: serviceName: tomcat-service servicePort: 8080
# 创建 [root@master ~]# kubectl create -f ingress-https.yaml ingress.extensions/ingress-https created # 查看 [root@master ~]# kubectl get ing ingress-https -n dev NAME HOSTS ADDRESS PORTS AGE ingress-https nginx.itheima.com,tomcat.itheima.com 80, 443 6s # 查看详情 [root@master ~]# kubectl describe ing ingress-https -n dev Name: ingress-https Namespace: dev Address: Default backend: default-http-backend:80 (<none>) TLS: tls-secret terminates nginx.itheima.com,tomcat.itheima.com Rules: Host Path Backends ---- ---- -------- nginx.itheima.com / nginx-service:80 (10.244.2.54:80,10.244.2.56:80,10.244.2.57:80 + 3 more...) tomcat.itheima.com / tomcat-service:8080 (10.244.2.55:8080,10.244.3.67:8080,10.244.3.68:8080) Annotations: Events: <none> # 查看service [root@master ~]# kubectl get svc -n ingress-nginx NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE ingress-nginx NodePort 10.110.59.157 <none> 80:30073/TCP,443:30254/TCP 110m # 80 对应的 http服务 443 对应https服务 # 下面可以通过浏览器访问https://nginx.itheima.com:30254和 https://tomcat.itheima.com:30254来查看了
