这里直接是安装和演示的过程，概念理论部分自行到官网学习，就不再赘述了。
Ingress 介绍：https://kubernetes.io/zh/docs/concepts/services-networking/ingress/
一、k8s 安装 ingress-nginx
下载 Ingress-nginx yaml文件
[root@k8s-master01 ingress-nginx]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml
[root@k8s-master01 ingress-nginx]# wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/provider/baremetal/service-nodeport.yaml
[root@k8s-master01 ingress-nginx]# ls
mandatory.yaml service-nodeport.yamlmandatory.yaml下载后需要添加hostNetwork: true，否则无法通过 K8s 节点 IP 地址绑定域名外部访问。
ingress-controller 会直接使用 K8s 物理机的 DNS 来解析域名，而不再使用 K8s 内部的 DNS 来解析域名。
mandatory.yaml配置修改如下：
...
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-ingress-controller
namespace: ingress-nginx
labels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
spec:
replicas: 1
selector:
matchLabels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
template:
metadata:
labels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
annotations:
prometheus.io/port: "10254"
prometheus.io/scrape: "true"
spec:
# wait up to five minutes for the drain of connections
# 添加 hostNetwork: true
hostNetwork: true
terminationGracePeriodSeconds: 300
serviceAccountName: nginx-ingress-serviceaccount
nodeSelector:
kubernetes.io/os: linux
service-nodeport.yaml配置
apiVersion: v1
kind: Service
metadata:
name: ingress-nginx
namespace: ingress-nginx
labels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
spec:
type: NodePort
ports:
- name: http
port: 80
targetPort: 80
protocol: TCP
- name: https
port: 443
targetPort: 443
protocol: TCP
selector:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx修改好后，开始安装 Ingress-nginx
[root@k8s-master01 ingress-nginx]# kubectl apply -f mandatory.yaml
[root@k8s-master01 ingress-nginx]# kubectl apply -f service-nodeport.yaml查看 Ingress Pod 是否 Running 状态
[root@k8s-master01 ingress-nginx]# kubectl get pod -n ingress-nginx
NAME READY STATUS RESTARTS AGE
nginx-ingress-controller-6979d75b9d-fqf8v 1/1 Running 0 73s二、创建实例测试 Ingress
my-nginx.yml 配置文件：
apiVersion: apps/v1
kind: Deployment
metadata:
name: my-nginx
spec:
selector:
matchLabels:
run: my-nginx
replicas: 1
template:
metadata:
labels:
run: my-nginx
spec:
containers:
- name: my-nginx
image: nginx:latest
resources:
limits:
memory: "128Mi"
cpu: "500m"
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx-service
spec:
selector:
run: my-nginx
type: ClusterIP
ports:
- protocol: TCP
port: 8080
targetPort: 80
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: example-ingress
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /$1
spec:
rules:
- host: test.ingress.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: nginx-service
port:
number: 8080创建 Deployment、service、ingress
[root@k8s-master01 ingress-nginx]# kubectl apply -f my-nginx.yml
deployment.apps/my-nginx created
service/nginx-service created
ingress.networking.k8s.io/example-ingress created检查是否创建成功
[root@k8s-master01 ingress-nginx]# kubectl get ingress -o wide
NAME CLASS HOSTS ADDRESS PORTS AGE
example-ingress test.ingress.com 10.233.31.38 80 40s
[root@k8s-master01 ingress-nginx]# kubectl get pod
NAME READY STATUS RESTARTS AGE
my-nginx-6d97ddfff5-7jkp6 1/1 Running 0 44s
[root@k8s-master01 ingress-nginx]# kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.233.0.1 443/TCP 30d
nginx-service ClusterIP 10.233.39.79 8080/TCP 48s 
nginx-ingress-controller所在的节点与域名做好hosts绑定，就可以访问后端 Pod 服务了
[root@k8s-master01 ingress-nginx]# kubectl get pod -n ingress-nginx -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx-ingress-controller-6979d75b9d-fqf8v 1/1 Running 0 9m49s 192.168.3.248 k8s-node01
[root@k8s-master01 ingress-nginx]# vim /etc/hosts
[root@k8s-master01 ingress-nginx]# tail -1 /etc/hosts
192.168.3.248 test.ingress.com 我这里nginx-ingress-controller所在的节点是 k8s-node01，它的IP地址是192.168.3.248，所以把刚刚自定义的域名进行绑定解析。
访问成功test.ingress.com域名
三、优化 Ingress-nginx
通过上述的实验，我们可以发现默认是 Deployment 类型，将 Ingress 改为 DaemonSet 类似，让每个工作节点运行一个 ingress-controller，这样可以达到高可用效果，某个节点宕机了，不会影响 Ingress 工作。
其实生成环境的做法是在 K8s 工作节点上安装 keepalive ，通过 VIP 作为对外 IP地址与域名解析。
- 将 Deployment 改为 DaemonSet；并删掉 replicas；
- 添加字段 hostNetwork: true(刚刚在上面已经添加了)
- nodeSelector：给工作节点打上标签，master 节点不会部署。
把之前的 ingress-controller 删除掉，修改配置文件后，重新创建：
[root@k8s-master01 ingress-nginx]# kubectl delete -f mandatory.yaml修改 mandatory.yaml 配置文件：
[root@k8s-master01 ingress-nginx]# vim mandatory.yaml
对 master 设置污点，其他工作节点都部署
[root@k8s-master01 ingress-nginx]# kubectl get nodes
NAME STATUS ROLES AGE VERSION
k8s-master01 Ready control-plane,master 30d v1.21.5
k8s-node01 Ready worker 30d v1.21.5
k8s-node02 Ready worker 30d v1.21.5
[root@k8s-master01 ingress-nginx]# kubectl taint nodes k8s-master01 node-role.kubernetes.io/master=true:NoSchedule
node/k8s-master01 tainted重新创建 Ingress-nginx，以及查看状态
[root@k8s-master01 ingress-nginx]# kubectl apply -f mandatory.yaml
[root@k8s-master01 ingress-nginx]# kubectl get pod -n ingress-nginx -o wide
无论域名绑定那个工作节点IP地址，都可以解析到后端的 Pod 服务了，一个节点宕机了不会影响 Ingress 工作。
最后，以上属于测试环境实验，想要真正的 Ingress 高可用，还是得结合 Keepalived 或者 SLB 一起实现。