4 Service-LoadBalance
通常需要第三方云提供商支持，有约束性
Ingress
官网：https://kubernetes.io/docs/concepts/services-networking/ingress/
GitHub Ingress Nginx:https://github.com/kubernetes/ingress-nginx
Nginx Ingress Controller:<https://kubernetes.github.io/ingress-nginx/
An API object that manages external access to the services in a cluster, typically HTTP.
Ingress can provide load balancing, SSL termination and name-based virtual hosting.
Ingress exposes HTTP and HTTPS routes from outside the cluster to services within the cluster. Traffic routing is controlled by rules defined on the Ingress resource.
internet
|
[ Ingress ]
--|-----|--
[ Services ]
可以发现，Ingress就是帮助我们访问集群内的服务的。为了彰显其优势，我们在使用Ingress之前，先以一个简单案例出发。
4.1使用NodePort类型的service在K8S集群中部署tomcat
（也为了演示将service写在yaml文件中）
浏览器想要访问这个tomcat，也就是外部要访问该tomcat，用之前的Service-NodePort的方式是可以的，比如暴露一个端口，只需要访问 :即可。
01 创建yaml文件
vim my-tomcat.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcat-deployment
labels:
app: tomcat
spec:
replicas: 1
selector:
matchLabels:
app: tomcat
template:
metadata:
labels:
app: tomcat
spec:
containers:
- name: tomcat
image: tomcat
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: tomcat-service
spec:
ports:
- port: 80
protocol: TCP
targetPort: 8080
selector:
app: tomcat
type: NodePort
02 创建service
`创建pod、service`
[root@henry001 network]# kubectl apply -f my-tomcat.yaml
deployment.apps/tomcat-deployment created
service/tomcat-service created
`查看service`
[root@henry001 network]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 42h
tomcat-service NodePort 10.106.112.183 <none> 80:30747/TCP 31s
whoami-deployment NodePort 10.103.129.91 <none> 8000:31999/TCP 42m
`查看pod`
[root@henry001 network]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-6b9d6f8547-6mmh2 1/1 Running 0 69s
tomcat-deployment-6b9d6f8547-79nck 1/1 Running 0 69s
tomcat-deployment-6b9d6f8547-c8bps 1/1 Running 0 69s
`查看deployment`
[root@henry001 network]# kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
nginx 1/1 1 1 24h
tomcat-deployment 3/3 3 3 97s
显然，Service-NodePort的方式生产环境不推荐使用，那接下来就基于上述需求，使用Ingress实现访问tomcat的需求。下面就开始讲解使用ingress插件来实现外网访问集群pod。
4.2 使用ingress实现
4.2.1架构图
说明：
本文中采用的ingress-controller是nginx-ingress-controller，具体详情可以参考官网：https://www.nginx.com/products/nginx/kubernetes-ingress-controller；
大家也可以根据自己需要采用不同的ingress-controller，可参考https://kubernetes.io/docs/concepts/services-networking/ingress-controllers/
4.2.2 实例
(1)以Deployment方式创建Pod，该Pod为Ingress Nginx Controller，要想让外界访问，可以通过Service的NodePort或者HostPort方式，这里选择HostPort，比如指定henry002机器上运行：
# 确保nginx-controller运行到henry002节点上
kubectl label node henry002 name=ingress
`先下载mandatory.yaml文件，下载地址：https://github.com/kubernetes/ingress-nginx/blob/nginx-0.20.0/deploy/mandatory.yaml，并对mandatory.yaml并进行修改，如下：
# 使用HostPort方式运行，需要增加配置
hostNetwork: true #使用hostport
nodeSelector:
name: ingress #指定节点
# 搜索nodeSelector，并且要确保henry002节点上的80和443端口没有被占用，镜像拉取需要较长的时间，这块要特别注意一下
#运行mandatory.yaml
kubectl apply -f mandatory.yaml
#查看ingress-nginx命名空间下的资源
kubectl get all -n ingress-nginx
(2)查看henry002的80和443端口
lsof -i tcp:80
lsof -i tcp:443
(3)创建tomcat的pod和service
记得将之前的tomcat删除：kubectl delete -f my-tomcat.yaml
vim tomcat.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcat-deployment
labels:
app: tomcat
spec:
replicas: 3
selector:
matchLabels:
app: tomcat
template:
metadata:
labels:
app: tomcat
spec:
containers:
- name: tomcat
image: tomcat
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: tomcat-service
spec:
ports:
- port: 80
protocol: TCP
targetPort: 8080
selector:
app: tomcat
`执行yaml文件`
[root@henry001 network]# kubectl apply -f tomcat-ingress.yaml
deployment.apps/tomcat-deployment created
service/tomcat-service created
`查看service`
[root@henry001 network]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 43h
tomcat-service ClusterIP 10.101.231.253 <none> 80/TCP 20s
whoami-deployment NodePort 10.103.129.91 <none> 8000:31999/TCP 150m
`查看pod`
[root@henry001 network]# kubectl get pods
NAME READY STATUS RESTARTS AGE
tomcat-deployment-6b9d6f8547-8wxgx 1/1 Running 0 42s
tomcat-deployment-6b9d6f8547-hrhrr 1/1 Running 0 42s
tomcat-deployment-6b9d6f8547-p7zhz 1/1 Running 0 42s
kubectl get svc
kubectl get pods
(4)创建Ingress以及定义转发规则
1>创建 nginx-ingress.yaml文件
vim nginx-ingress.yaml
#ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-ingress
spec:
rules:
- host: tomcat.henry.com
http:
paths:
- path: /
backend:
serviceName: tomcat-service
servicePort: 80
2>创建ingress并查看
`创建ingress`
[root@henry001 network]# kubectl apply -f nginx-ingress.yaml
ingress.extensions/nginx-ingress created
`查看ingress`
[root@henry001 network]# kubectl get ingress
NAME HOSTS ADDRESS PORTS AGE
nginx-ingress tomcat.henry.com 80 47s
`查看ingress详细信息`
[root@henry001 network]# kubectl describe ingress nginx-ingress
Name: nginx-ingress
Namespace: default
Address:
Default backend: default-http-backend:80 (<none>)
Rules:
Host Path Backends
---- ---- --------
tomcat.henry.com
/ tomcat-service:80 (192.168.217.22:8080,192.168.254.215:8080,192.168.254.216:8080)
Annotations:
kubectl.kubernetes.io/last-applied-configuration: {"apiVersion":"extensions/v1beta1","kind":"Ingress","metadata":{"annotations":{},"name":"nginx-ingress","namespace":"default"},"spec":{"rules":[{"host":"tomcat.henry.com","http":{"paths":[{"backend":{"serviceName":"tomcat-service","servicePort":80},"path":"/"}]}}]}}
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal CREATE 53s nginx-ingress-controller Ingress default/nginx-ingress
(5)修改win的hosts文件，添加dns解析
182.92.105.161 tomcat.henry.com
(6)打开浏览器，访问tomcat.henry.com
总结：如果以后想要使用Ingress网络，其实只要定义ingress，service和pod即可，前提是要保证nginx ingress controller已经配置好了。
