Ingress介绍
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
ngress（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
k8s安装2022新版ingress-nginx详细步骤
注意了，我们这里没有使用LoadBalancer，所以要将上文yaml文件中的type改一下
type: LoadBalancer #替换为NodePort type: NodePort
# 创建ingress-nginx [root@master ingress-controller]# kubectl apply -f ingress-nginx.yaml # 查看ingress-nginx [root@master ingress-controller]# kubectl get pods -n ingress-nginx NAME READY STATUS RESTARTS AGE ingress-nginx-admission-create-gvjt4 0/1 Completed 0 16m ingress-nginx-admission-patch-695qk 0/1 Completed 0 16m ingress-nginx-controller-84c544699d-577kf 1/1 Running 0 16m # 查看service [root@master ingress-controller]# kubectl get svc -n ingress-nginx NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE ingress-nginx-controller NodePort 10.107.236.215 <none> 80:31726/TCP,443:31974/TCP 17m ingress-nginx-controller-admission ClusterIP 10.106.83.195 <none> 443/TCP 17m
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
# Deployment控制3个nginx 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 --- # Deployment控制3个tomcat 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 --- # nginx-service关联nginx apiVersion: v1 kind: Service metadata: name: nginx-service namespace: dev spec: selector: app: nginx-pod clusterIP: None type: ClusterIP ports: - port: 80 targetPort: 80 --- # nginx-tomcat关联tomcat 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 k8sYamlForCSDN]# vi tomcat-nginx.yaml [root@master k8sYamlForCSDN]# kubectl create ns dev namespace/dev created [root@master k8sYamlForCSDN]# kubectl apply -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 k8sYamlForCSDN]# kubectl get svc -n dev NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE nginx-service ClusterIP None <none> 80/TCP 36s tomcat-service ClusterIP None <none> 8080/TCP 36s
Http代理(ingress-http.yaml)
创建ingress-http.yaml
注意我们在 Ingress 资源对象中添加了一个 annotations：kubernetes.io/ingress.class: “nginx”，这就是指定让这个 Ingress 通过 ingress-nginx 来处理，如果不添加则不会被ingress控制器所监控到！
apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: ingress-http namespace: dev annotations: kubernetes.io/ingress.class: "nginx" spec: rules: - host: nginx.itheima.com # 主机，域名，ip http: paths: - path: / # 路径 url：host/path pathType: Prefix backend: service: name: nginx-service # 访问url会转到这个service的80端口上去 port: number: 80 - host: tomcat.itheima.com http: paths: - path: / # 路径 url：host/path pathType: Prefix backend: service: name: tomcat-service # 访问url会转到这个service的80端口上去 port: number: 8080
# 创建 [root@master k8sYamlForCSDN]# kubectl apply -f ingress-http.yaml ingress.networking.k8s.io/ingress-http created # 查看 [root@master k8sYamlForCSDN]# kubectl get ingress ingress-http -n dev NAME CLASS HOSTS ADDRESS PORTS AGE ingress-http <none> nginx.itheima.com,tomcat.itheima.com 80 36s # 查看详情 [root@master k8sYamlForCSDN]# kubectl get ingress ingress-http -n dev NAME CLASS HOSTS ADDRESS PORTS AGE ingress-http <none> nginx.itheima.com,tomcat.itheima.com 10.107.236.215 80 16m [root@master k8sYamlForCSDN]# kubectl describe ingress ingress-http -n dev Name: ingress-http Labels: <none> Namespace: dev Address: 10.107.236.215 Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>) Rules: Host Path Backends ---- ---- -------- nginx.itheima.com / nginx-service:80 (10.244.1.106:80,10.244.1.107:80,10.244.2.45:80) tomcat.itheima.com / tomcat-service:8080 (10.244.1.108:8080,10.244.2.43:8080,10.244.2.44:8080) Annotations: kubernetes.io/ingress.class: nginx Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Sync 15m (x2 over 16m) nginx-ingress-controller Scheduled for sync [root@master k8sYamlForCSDN]# # 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:31726和 nginx.itheima.com:31726查看效果了
[root@master ingress-controller]# kubectl get pods,svc,ingress -n ingress-nginx NAME READY STATUS RESTARTS AGE pod/ingress-nginx-admission-create-gvjt4 0/1 Completed 0 20m pod/ingress-nginx-admission-patch-695qk 0/1 Completed 0 20m pod/ingress-nginx-controller-84c544699d-577kf 1/1 Running 0 20m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/ingress-nginx-controller NodePort 10.107.236.215 <none> 80:31726/TCP,443:31974/TCP 20m service/ingress-nginx-controller-admission ClusterIP 10.106.83.195 <none> 443/TCP 20m [root@master k8sYamlForCSDN]# kubectl get pods,svc,ingress -n dev NAME READY STATUS RESTARTS AGE pod/nginx-deployment-6756f95949-9zjrd 1/1 Running 0 17m pod/nginx-deployment-6756f95949-k6k7d 1/1 Running 0 17m pod/nginx-deployment-6756f95949-xk9jk 1/1 Running 0 17m pod/tomcat-deployment-76bccfb47c-2gc9j 1/1 Running 0 17m pod/tomcat-deployment-76bccfb47c-5k6lx 1/1 Running 0 17m pod/tomcat-deployment-76bccfb47c-wt7wv 1/1 Running 0 17m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/nginx-service ClusterIP None <none> 80/TCP 17m service/tomcat-service ClusterIP None <none> 8080/TCP 17m NAME CLASS HOSTS ADDRESS PORTS AGE ingress.networking.k8s.io/ingress-http <none> nginx.itheima.com,tomcat.itheima.com 10.107.236.215 80 17m
Https代理(ingress-https.yaml)
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: networking.k8s.io/v1 kind: Ingress metadata: name: ingress-https namespace: dev annotations: kubernetes.io/ingress.class: "nginx" spec: tls: - hosts: - nginx.itheima.com - tomcat.itheima.com secretName: tls-secret # 指定秘钥 rules: - host: nginx.itheima.com # 主机，域名，ip http: paths: - path: / # 路径 url：host/path pathType: backend: service: name: nginx-service # 访问url会转到这个service的80端口上去 port: number: 80 - host: tomcat.itheima.com http: paths: - path: / # 路径 url：host/path pathType: Prefix backend: service: name: tomcat-service # 访问url会转到这个service的80端口上去 port: number: 8080
# 删除验证 [root@master k8sYamlForCSDN]#kubectl get validatingwebhookconfigurations ingress-nginx-admission kubectl delete -A ValidatingWebhookConfiguration ingress-nginx-admission # 创建 [root@master k8sYamlForCSDN]# kubectl apply -f ingress-https.yaml ingress.networking.k8s.io/ingress-https created # 查看 [root@master k8sYamlForCSDN]# kubectl get ing ingress-https -n dev NAME CLASS HOSTS ADDRESS PORTS AGE ingress-https <none> nginx.itheima.com,tomcat.itheima.com 10.107.236.215 80, 443 98s # 查看详情 [root@master k8sYamlForCSDN]# kubectl describe ing ingress-https -n dev Name: ingress-https Labels: <none> Namespace: dev Address: 10.107.236.215 Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>) TLS: tls-secret terminates nginx.itheima.com,tomcat.itheima.com Rules: Host Path Backends ---- ---- -------- nginx.itheima.com / nginx-service:80 (10.244.1.106:80,10.244.1.107:80,10.244.2.45:80) tomcat.itheima.com / tomcat-service:8080 (10.244.1.108:8080,10.244.2.43:8080,10.244.2.44:8080) Annotations: kubernetes.io/ingress.class: nginx Events: Type Reason Age From Message ---- ------ ---- ---- ------- Normal Sync 103s (x2 over 118s) nginx-ingress-controller Scheduled for sync # 下面可以通过浏览器访问https://nginx.itheima.com:31974和 https://tomcat.itheima.com:31974来查看了
