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【K8s】Ingress的使用
上一章中,NotePort和LoadBalancer类型的Service可给集群外部机器提供访问,但这两种类型都有缺点:由此,Ingress资源对象出现,Ingress或者一个LB就可以满足暴露多个Service的需求。总结就是ingress中定义转发规则,ingress controller中解析规则,完成转发Ingress(以Nginx为例)的工作原理如下:下载ingress的yaml文件:创
一、Ingress介绍
1、Ingress的作用
上一章中,NotePort和LoadBalancer类型的Service可给集群外部机器提供访问,但这两种类型都有缺点:
- NodePort方式会占用很多集群机器的端口,当集群服务变多的时候,这个缺点愈发明显
- LB方式的缺点是每个service需要一个LB,浪费、麻烦,并且需要k8s之外设备的支持
由此,Ingress资源对象出现,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。
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。
- ingress: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
总结就是ingress中定义转发规则,ingress controller中解析规则,完成转发
2、Ingress工作流程
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
二、Ingress使用
1、测试数据准备
下载ingress的yaml文件:
# 创建文件夹
[root@k8s-master01 ~] mkdir ingress-controller
[root@k8s-master01 ~] cd ingress-controller/
# 获取ingress-nginx,本次案例使用的是0.30版本
[root@k8s-master01 ingress-controller] wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml
[root@k8s-master01 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的pod和Service
# 创建ingress-nginx
[root@k8s-master01 ingress-controller] kubectl apply -f ./
# 查看ingress-nginx
[root@k8s-master01 ingress-controller] kubectl get pod -n ingress-nginx
NAME READY STATUS RESTARTS AGE
pod/nginx-ingress-controller-fbf967dd5-4qpbp 1/1 Running 0 12h
# 查看service
# 32240端口是http下,31335是https下的
[root@k8s-master01 ingress-controller] kubectl get svc -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx NodePort 10.98.75.163 <none> 80:32240/TCP,443:31335/TCP 11h
创建pod和Service,结构如下:
使用- - -把两个deploy和service的配置写一起:
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 # Service端口
targetPort: 80 # pod端口
---
apiVersion: v1
kind: Service
metadata:
name: tomcat-service
namespace: dev
spec:
selector:
app: tomcat-pod
clusterIP: None
type: ClusterIP
ports:
- port: 8080 # Service端口
targetPort: 8080
# 创建
[root@k8s-master01 ~] kubectl create -f tomcat-nginx.yaml
# 查看
[root@k8s-master01 ~] kubectl get svc -n dev
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx-service ClusterIP None <none> 80/TCP 48s
tomcat-service ClusterIP None <none> 8080/TCP 48s
2、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 # 即以后访问nginx.itheima.com/就转发到nginx-service服务的80端口
- host: tomcat.itheima.com
http:
paths:
- path: /
backend:
serviceName: tomcat-service
servicePort: 8080
创建Ingress:
# 创建
[root@k8s-master01 ~] kubectl create -f ingress-http.yaml
ingress.extensions/ingress-http created
# 查看
[root@k8s-master01 ~] kubectl get ing ingress-http -n dev
NAME HOSTS ADDRESS PORTS AGE
ingress-http nginx.itheima.com,tomcat.itheima.com 80 22s
# 查看详情
[root@k8s-master01 ~] kubectl describe ing ingress-http -n dev
...
Rules:
Host Path Backends
---- ---- --------
nginx.itheima.com / nginx-service:80 (10.244.1.96:80,10.244.1.97:80,10.244.2.112:80)
tomcat.itheima.com / tomcat-service:8080(10.244.1.94:8080,10.244.1.95:8080,10.244.2.111:8080)
...
# 接下来,在本地电脑上配置host文件,让上面的两个域名解析到192.168.109.100(master)上
# 然后,就可以分别访问http://tomcat.itheima.com:32240 和 http://nginx.itheima.com:32240 查看效果了
3、HTTPS代理
生成证书和创建密钥:
# 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Ingress:
# 创建
[root@k8s-master01 ~] kubectl create -f ingress-https.yaml
ingress.extensions/ingress-https created
# 查看
[root@k8s-master01 ~] kubectl get ing ingress-https -n dev
NAME HOSTS ADDRESS PORTS AGE
ingress-https nginx.itheima.com,tomcat.itheima.com 10.104.184.38 80, 443 2m42s
# 查看详情
[root@k8s-master01 ~] kubectl describe ing ingress-https -n dev
...
TLS:
tls-secret terminates nginx.itheima.com,tomcat.itheima.com
Rules:
Host Path Backends
---- ---- --------
nginx.itheima.com / nginx-service:80 (10.244.1.97:80,10.244.1.98:80,10.244.2.119:80)
tomcat.itheima.com / tomcat-service:8080(10.244.1.99:8080,10.244.2.117:8080,10.244.2.120:8080)
...
接下来就可以使用https访问集群中的nginx和tomcat服务了:
https://nginx.itheima.com:31335
https://tomcat.itheima.com:31335
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