kubernetes—Ingress详解
IngressIngress介绍Ingress使用环境准备搭建ingress环境准备service和podHttp代理(ingress-http.yaml)Https代理(ingress-https.yaml)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
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Ingress
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
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
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
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