文章目录
- 一、ingress介绍
- 二、ingress的工作原理
- 三、ingress的使用
- 1、搭建ingress环境
- 2、准备service和pod
- 3、创建http代理
- 4、创建https代理
一、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
二、ingress的工作原理
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
三、ingress的使用
1、搭建ingress环境
[root@master ingress]# ls
ingress-controller-deploy.yaml ingress-nginx-controllerv1.1.0.tar.gz kube-webhook-certgen-v1.1.0.tar.gz tomcat-nginx.yaml
[root@master ingress]#
# ingress-controller-deploy.yaml 为安装ingress-nginx的yaml文件
# ingress-nginx-controllerv1.1.0.tar.gz 为安装ingress-ngix的镜像文件
# 执行安装完成之后
# 查看ingress-nginx
[root@master ingress]# kubectl get pod -n ingress-nginx
NAME READY STATUS RESTARTS AGE
ingress-nginx-controller-7cd558c647-6mvc5 1/1 Running 1 (13m ago) 133m
ingress-nginx-controller-7cd558c647-zcqq9 1/1 Running 1 (14m ago) 133m
# 查看service
[root@master ingress]# kubectl get svc -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx-controller NodePort 10.1.87.167 <none> 80:31047/TCP,443:30526/TCP 133m
ingress-nginx-controller-admission ClusterIP 10.1.39.127 <none> 443/TCP 133m
[root@master ingress]#
2、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:latest
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pod
[root@master ingress]# kubectl apply -f tomcat-nginx.yaml
# 查看相应的pod和service
[root@master ingress]# kubectl get pod -n dev
NAME READY STATUS RESTARTS AGE
nginx-deployment-6756f95949-dzsk8 1/1 Running 0 14m
nginx-deployment-6756f95949-jr7nq 1/1 Running 0 14m
nginx-deployment-6756f95949-kwhf9 1/1 Running 0 14m
tomcat-deployment-b5d5d98cb-hmplf 1/1 Running 0 14m
tomcat-deployment-b5d5d98cb-lftm9 1/1 Running 0 14m
tomcat-deployment-b5d5d98cb-x5fld 1/1 Running 0 14m
[root@master ingress]# kubectl get service -n dev
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
nginx-service ClusterIP None <none> 80/TCP 14m
tomcat-service ClusterIP None <none> 8080/TCP 14m
[root@master ingress]#
3、创建http代理
创建ingress-http.yaml
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: ingress-http
namespace: dev
spec:
rules:
- host: nginx.yuanke.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: nginx-service
port:
number: 80
- host: tomcat.yuanke.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: tomcat-service
port:
number: 8080
# 创建
[root@master ingress]# kubectl create -f ingress-http.yaml --validate=false
ingress.networking.k8s.io/ingress-http created
# 查看
[root@master ingress]# kubectl get ingress -n dev
NAME CLASS HOSTS ADDRESS PORTS AGE
ingress-http <none> nginx.yuanke.com,tomcat.yuanke.com 80 21s
# 查看详情
[root@master ingress]# kubectl describe ingress ingress-http -n dev
Name: ingress-http
Labels: <none>
Namespace: dev
Address:
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
Rules:
Host Path Backends
---- ---- --------
nginx.yuanke.com
/ nginx-service:80 (10.244.1.96:80,10.244.1.97:80,10.244.2.99:80)
tomcat.yuanke.com
/ tomcat-service:8080 (10.244.1.96:80,10.244.1.97:80,10.244.2.99:80)
Annotations: <none>
Events: <none>
[root@master ingress]#
http://nginx.yuanke.com:31047进行访问
4、创建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=yuanke.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
spec:
tls:
- hosts:
- nginx.yuanke.com
- tomcat.yuanke.com
secretName: tls-secret # 指定秘钥
rules:
- host: nginx.yuanke.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: nginx-service
port:
number: 80
- host: tomcat.yuanke.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: tomcat-service
port:
number: 8080
# 创建
[root@master ingress]# kubectl apply -f ingress-https.yaml
ingress.networking.k8s.io/ingress-https created
# 查看
[root@master ingress]# kubectl get ingress -n dev
NAME CLASS HOSTS ADDRESS PORTS AGE
ingress-http <none> nginx.yuanke.com,tomcat.yuanke.com 80, 443 15m
ingress-https <none> nginx.yuanke.com,tomcat.yuanke.com 80, 443 3s
# 查看详情
[root@master ingress]# kubectl describe ingress ingress-https -n dev
Name: ingress-https
Labels: <none>
Namespace: dev
Address:
Default backend: default-http-backend:80 (<error: endpoints "default-http-backend" not found>)
TLS:
tls-secret terminates nginx.yuanke.com,tomcat.yuanke.com
Rules:
Host Path Backends
---- ---- --------
nginx.yuanke.com
/ nginx-service:80 (10.244.1.3:80,10.244.2.6:80,10.244.3.3:80)
tomcat.yuanke.com
/ tomcat-service:8080 (10.244.1.4:8080,10.244.2.5:8080,10.244.3.4:8080)
Annotations: <none>
Events: <none>
[root@master ingress]#
https://nginx.yuanke.com:30526进行访问