我们学习语言第一个想法就是在环境搭建好了之后写一个Helloworld，我们学习如何在 k8s 上部署应用时，部署一个简单的 nginx，能够访问到它的配置页面。由于它五脏俱全，功能简单，无状态，可以当做 k8s 部署应用的 hello, world：
实验目的：
利用ingress-nginx暴露服务供外网访问，版本：0.30.0
实验步骤：
1，下载ingress-nginx安装配置文件
wget https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/deploy/static/mandatory.yaml -O ingress-nginx.yaml
2，在ingress-nginx.yaml文件最后增加service的安装配置
---
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
nodePort: 30010
protocol: TCP
- name: https
port: 443
targetPort: 443
nodePort: 30011
protocol: TCP
selector:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
3，安装ingress-nginx，安装了namespace，nginx-ingress-controller，ingress-nginx
kubectl apply -f ingress-nginx.yaml
输出：
namespace/ingress-nginx created
configmap/nginx-configuration created
configmap/tcp-services created
configmap/udp-services created
serviceaccount/nginx-ingress-serviceaccount created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRole is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRole
clusterrole.rbac.authorization.k8s.io/nginx-ingress-clusterrole created
Warning: rbac.authorization.k8s.io/v1beta1 Role is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 Rolerole.rbac.authorization.k8s.io/nginx-ingress-role created
Warning: rbac.authorization.k8s.io/v1beta1 RoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 RoleBindingrolebinding.rbac.authorization.k8s.io/nginx-ingress-role-nisa-binding created
Warning: rbac.authorization.k8s.io/v1beta1 ClusterRoleBinding is deprecated in v1.17+, unavailable in v1.22+; use rbac.authorization.k8s.io/v1 ClusterRoleBindingclusterrolebinding.rbac.authorization.k8s.io/nginx-ingress-clusterrole-nisa-binding createddeployment.apps/nginx-ingress-controller created
limitrange/ingress-nginx created
service/ingress-nginx created
4，查看安装结果：
1，namespace是k8s的命名空间，旨在对一组资源和对象创建一个抽象空间集合，比如可以用来将系统内部的对象划分为不同的项目组或用户组。常见的 pod, service, replication controller 和 deployment 等都是属于某一个 namespace 的（默认是 default）；
2，pod是一组紧密关联的容器集合，Pod就是共享IPC、Network和UTS namespace，是K8S调度的基本单位。Pod 的设计理念是支持多个容器在一个 Pod 中共享网络和文件系统，可以通过进程间通信和文件共享这种简单高效的方式组合完成服务。这个容器就是ingress-nginx的控制器；
3，service是对一组提供相同功能的 Pods 的抽象，并为它们提供一个统一的入口。借助 Service，应用可以方便的实现服务发现与负载均衡，并实现应用的零宕机升级。Service 通过标签来选取服务后端，一般配合 Replication Controller 或者 Deployment 来保证后端容器的正常运行。这些匹配标签的 Pod IP 和端口列表组成 endpoints，由 kube-proxy 负责将服务 IP 负载均衡到这些 endpoints 上。Service有四种类型（ClusterIP，NodePort，LoadBalancer，ExternalName）为对外暴露的接口，说明了集群的机器均对外暴露30010和30011两个接口；
//查看namespace
kubectl get namespaces
NAME STATUS AGE
default Active 7d18h
ingress-nginx Active 22s
kube-node-lease Active 7d18h
kube-public Active 7d18h
kube-system Active 7d18h
kubernetes-dashboard Active 41h//查看pod
kubectl get pods -n ingress-nginx
NAME READY STATUS RESTARTS AGE
nginx-ingress-controller-54b86f8f7b-lghw4 1/1 Running 0 66s//查看service
kubectl get services -n ingress-nginx
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
ingress-nginx NodePort 10.1.64.18680:30010/TCP,443:30011/TCP 75s
5，安装nginx pod并暴露80端口：
//nginx.yaml
apiVersion: v1
kind: Pod
metadata:
name: nginx
# 指定 label，便于检索
labels:
app: nginx
spec:
containers:
- name: nginx
# 指定镜像
image: nginx:alpine
# 指定暴露端口
ports:
- containerPort: 80
//使用kubectl apply，部署 Pod
kubectl apply -f nginx.yaml
pod/nginx created
//校验部署状态，此时 STATUS 为 Running 表明部署成功
kubectl get pods nginx -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx 1/1 Running 0 43h 10.244.3.4 pcno4
//获取更加详细的信息
kubectl describe pod nginx
Name: nginx
Namespace: default
Priority: 0
Node: pcno4/10.10.30.74
Start Time: Wed, 06 Jan 2021 15:16:28 +0800
Labels: app=nginx
Annotations:
Status: Running
IP: 10.244.3.4
IPs:
IP: 10.244.3.4
Containers:
nginx:
Container ID: docker://fa7b8ef84d0c2cb9bc3c7bc1bab7e94912fecada7f901f762da3898a8bcf65cc
Image: nginx:alpine
Image ID: docker-pullable://nginx@sha256:c2ce58e024275728b00a554ac25628af25c54782865b3487b11c21cafb7fabda
Port: 80/TCP
Host Port: 0/TCP
State: Running
Started: Wed, 06 Jan 2021 15:16:47 +0800
Ready: True
Restart Count: 0
Environment:
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from default-token-k9grl (ro)
Conditions:
Type Status
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
default-token-k9grl:
Type: Secret (a volume populated by a Secret)
SecretName: default-token-k9grl
Optional: false
QoS Class: BestEffort
Node-Selectors:
Tolerations:
node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
每个 pod 都有一个IP地址，直接访问IP地址获取内容
curl 10.244.3.4Welcome to nginx! Welcome to nginx!
If you see this page, the nginx web server is successfully installed andworking. Further configuration is required.
For online documentation and support please refer to
nginx.org.
Commercial support is available at
nginx.com.Thank you for using nginx.
6，此时我们可以使用 kubectl exec 进入 Pod 的内部容器。如果 Pod 中有多个容器，使用 kubectl exec -c 指定容器
kubectl exec -it nginx sh
kubectl exec [POD] [COMMAND] is DEPRECATED and will be removed in a future version. Use kubectl exec [POD] -- [COMMAND] instead./ # vim /usr/share/nginx/html/index.html
//修改index.html文件改成自己希望加入的内容，然后退出重新使用curl命令查看
curl 10.244.3.4
#可以看到修改过的页面
//进入pod还可以查看网络情况，如下：
netstat -tan
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTENtcp 0 0 :::80 :::* LISTEN
wget -q -O - localhost
#可以看到页面文件内容
7，部署nginx至集群，在k8s中管理 Pod 的称作 Controller，我们可以使用 Deployment 这种 Controller 来为 Pod 进行扩容，当然它还可以滚动升级，回滚等等关于部署的事情，我们编写一个Deployment的资源配置文件
//nginxdelop.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx-deployment
spec:
#定位需要管理的Pod
selector:
matchLabels:
app: nginx
#需要部署的个数
replicas: 3
#指定要部署的Pod
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:alpine
ports:
- containerPort: 80
//kubectl apply 部署生效后查看 Pod 以及 Deployment 状态
kubectl get pods -o wide -l 'app=nginx'
//nginx-deployment 部署的三个 pod 全部成功
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
nginx 1/1 Running 0 46h 10.244.3.4 pcno4
nginx-deployment-7fb7fd49b4-b6tcw 1/1 Running 0 46h 10.244.3.5 pcno4
nginx-deployment-7fb7fd49b4-jxdx2 1/1 Running 0 46h 10.244.1.4 pcno5
nginx-deployment-7fb7fd49b4-spxgr 1/1 Running 0 46h 10.244.1.5 pcno5
//READY 3/3 表明全部部署成功
kubectl get deploy nginx-deployment
NAME READY UP-TO-DATE AVAILABLE AGE
nginx-deployment 3/3 3 3 46h
8，现在部署的这个nginx[pod]，对应第二步里建立的ingress-nginx的service，这样就可以通过下面的渠道被访问了：
集群对外的ip（机器ip:10.10.30.76:80）--> ingress(ingress-nginx NodePort ClusterIP: 10.1.64.186:30010/30011) --> nginx-service(CluserIP:10.1.169.124:80) --> nginx-deployment(IP:10.244.1.4/1.5/3.5/
10.10.30.76:30010 --| |-> 10.244.1.4:80
[serive:NodePort:ingress-nginx] [pod:nginx-ingress-controller] [service:nginx-service]
| 10.1.64.186 | --> | 10.244.1.7:80 | --> | 10.1.169.124:80 |-> 10.244.1.5:80
10.10.30.75:30010 --| |-> 10.244.3.4:80
10.10.30.74:30010 --| |-> 10.244.3.5:80
9，最后可以通过集群外机器直接用ip访问（如果进入不同nginxpod机器修改不同的nginx主页，然后多次访问就能看出集群的负载均衡在自动调用不同的node处理）如下：
//编辑所有的pods，将内部部署的网页全部添加node和ip相关的信息
kubectl exec -it nginx sh #10.244.3.4 pcno4 根据第7步kubectl get pods -o wide -l 'app=nginx'命令的结果添加node和ip信息
kubectl exec -it nginx-deployment-7fb7fd49b4-jxdx2 sh #10.244.3.5 pcno4
kubectl exec -it nginx-deployment-7fb7fd49b4-b6tcw sh #10.244.1.4 pcno5
kubectl exec -it nginx-deployment-7fb7fd49b4-spxgr sh #10.244.1.5 pcno5//在外网访问，可以看到四个不同的node的信息
curl http://10.10.30.76（75|74）:30010