kubernetes集群发布Pod 端口

创建测试环境

vi nginx.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      run: my-nginx
  replicas: 2
  template:
    metadata:
      labels:
        run: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80

验证服务启动

[root@kubm-02 ~]# kubectl get pods
NAME                        READY   STATUS    RESTARTS   AGE
my-nginx-756fb87568-jwgp8   1/1     Running   0          64s
my-nginx-756fb87568-vshxc   1/1     Running   0          64s
[root@kubm-02 ~]# 

[root@kubm-02 ~]# kubectl get pods -l run=my-nginx -o wide
NAME                        READY   STATUS    RESTARTS   AGE     IP             NODE         NOMINATED NODE   READINESS GATES
my-nginx-756fb87568-jwgp8   1/1     Running   0          2m12s   10.244.3.101   kubnode-01   <none>           <none>
my-nginx-756fb87568-vshxc   1/1     Running   0          2m12s   10.244.4.123   kubnode-02   <none>           <none>

检查 Pod 的 IP 地址：

[root@kubm-02 ~]# kubectl get pods -l run=my-nginx -o yaml | grep podIP
    podIP: 10.244.3.101
    podIP: 10.244.4.123

创建 Service

Kubernetes Service 从逻辑上定义了运行在集群中的一组 Pod，这些 Pod 提供了相同的功能。 当每个 Service 创建时，会被分配一个唯一的 IP 地址（也称为 clusterIP）。 这个 IP 地址与一个 Service 的生命周期绑定在一起，当 Service 存在的时候它也不会改变。 可以配置 Pod 使它与 Service 进行通信，Pod 知道与 Service 通信将被自动地负载均衡到该 Service 中的某些 Pod 上。

创建nginx 服务

kubectl expose 命令为 2个 Nginx 副本创建一个 Service：

[root@kubm-02 ~]# kubectl expose deployment/my-nginx
service/my-nginx exposed

验证服务启动

[root@kubm-02 ~]# kubectl  get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
my-nginx     ClusterIP   10.245.206.203   <none>        80/TCP    2m36s

查看详细信息

[root@kubm-02 ~]# kubectl describe svc my-nginx 
Name:              my-nginx
Namespace:         default
Labels:            <none>
Annotations:       <none>
Selector:          run=my-nginx
Type:              ClusterIP
IP:                10.245.206.203
Port:              <unset>  80/TCP
TargetPort:        80/TCP
Endpoints:         10.244.3.101:80,10.244.4.123:80
Session Affinity:  None
Events:            <none>

kubectl describe po my-nginx # 查看my-nginx pod的详细状态
kubectl describe rs my-nginx # 查看my-nginx replica set的详细状态
kubectl describe deployment my-nginx # 查看my-nginx deployment的详细状态

访问 Service

Kubernetes 支持两种主要的服务发现模式 —— 环境变量和 DNS。前者在单个节点上可用使用，然而后者必须使用 kube-dns 集群插件。

[root@kubm-02 ~]# kubectl get pods
NAME                        READY   STATUS    RESTARTS   AGE
my-nginx-756fb87568-jwgp8   1/1     Running   0          23m
my-nginx-756fb87568-vshxc   1/1     Running   0          23m

[root@kubm-02 ~]# kubectl exec my-nginx-756fb87568-jwgp8 -- printenv | grep SERVICE                         
KUBERNETES_SERVICE_HOST=10.245.0.1
KUBERNETES_SERVICE_PORT=443
KUBERNETES_SERVICE_PORT_HTTPS=443

DNS 解析测试

Kubernetes 提供 DNS ，如果它在集群中处于运行状态，可以通过如下命令来检查：

[root@kubm-02 ~]# kubectl get services kube-dns --namespace=kube-system
NAME       TYPE        CLUSTER-IP    EXTERNAL-IP   PORT(S)                  AGE
kube-dns   ClusterIP   10.245.0.10   <none>        53/UDP,53/TCP,9153/TCP   11d

验证服务解析

启动一个安装有curl 的镜像

[root@kubm-02 ~]# kubectl run curl --image=radial/busyboxplus:curl -i --tty

测试解析 my-nginx

[ root@curl-6bf6db5c4f-96nhg:/ ]$ nslookup my-nginx
Server:    10.245.0.10                                          《==== dns 服务器
Address 1: 10.245.0.10 kube-dns.kube-system.svc.cluster.local

Name:      my-nginx
Address 1: 10.245.206.203 my-nginx.default.svc.cluster.local    《==== my-nginx服务的集群IP地址
[ root@curl-6bf6db5c4f-96nhg:/ ]$ 

curl 测试

[ root@curl-6bf6db5c4f-96nhg:/ ]$ curl my-nginx 

........
<h2>Welcome to nginx!</h2>
.........

[ root@curl-6bf6db5c4f-96nhg:/ ]$ curl 10.245.206.203
........
<h2>Welcome to nginx!</h2>
......

服务资源扩容

收缩服务
[root@kubm-02 ~]# kubectl scale deployment my-nginx --replicas=0

验证
[root@kubm-02 ~]# kubectl get pods -o wide

No resources found.

扩容服务至2节点
[root@kubm-02 ~]# kubectl scale deployment my-nginx --replicas=2
deployment.extensions/my-nginx scaled

验证
[root@kubm-02 ~]# kubectl get pods -o wide                      
NAME                        READY   STATUS              RESTARTS   AGE   IP       NODE         NOMINATED NODE   READINESS GATES
my-nginx-756fb87568-gmgfq   0/1     ContainerCreating   0          1s    <none>   kubnode-02   <none>           <none>
my-nginx-756fb87568-gvhbm   0/1     ContainerCreating   0          1s    <none>   kubnode-01   <none>           <none>

清理服务

#直接使用配置文件删除
[root@kubm-02 ~]# kubectl delete -f nginx.yaml    
deployment.apps "my-nginx" deleted

#删除服务
[root@kubm-02 ~]# kubectl get svc
NAME         TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.245.0.1       <none>        443/TCP   11d
my-nginx     ClusterIP   10.245.206.203   <none>        80/TCP    48m

[root@kubm-02 ~]# kubectl delete  svc my-nginx 
service "my-nginx" deleted

[root@kubm-02 ~]# kubectl get svc              
NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
kubernetes   ClusterIP   10.245.0.1   <none>        443/TCP   11d