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k8s免安装-使用kubectl部署Pod, Deployment, LoadBalancer

2020/02/01 k8s 共 3549 字，约 11 分钟

如果你想要从零开始搭建自己的k8s集群参考我的这篇博客，预计花费时间为1天：从零开始在ubuntu上安装和使用k8s集群及报错解决

自己搭建k8s集群的难点之一是需要3台ubuntu虚拟机，要求电脑至少10G内存：操作系统4G内存，3台虚拟机需要6G内存。

另一个难度是对初学者来说，搭建太复杂了。

如果你不想手动搭建集群，只想体验和使用kubernetes集群，推荐使用digitalocean的kubernetes集群服务，自动搭建，无需安装。

digitalocean的kubernetes集群提供3台ubuntu虚拟机(node)，每台1核CPU，2G内存，共30$一个月，体验一天只要1$。

通过我的链接在digitalocean注册的新用户，可以获得100美元的2个月使用权，相当于前2个月免费用：DigitalOcean – sign up

创建kubernetes集群后，DO会提醒你使用kubectl或者doctl操作集群，我推荐kubectl这个通用工具。

在本地linux上安装kubectl，通过 kubectl 操作 k8s 集群。

echo "deb https://mirrors.aliyun.com/kubernetes/apt/ kubernetes-xenial main" | sudo tee -a /etc/apt/sources.list.d/kubernetes.list
sudo gpg --keyserver keyserver.ubuntu.com --recv-keys BA07F4FB #对安装包进行签名
sudo gpg --export --armor BA07F4FB | sudo apt-key add -
sudo apt-get update
sudo apt install kubectl

安装完成后下载yaml配置文件到目录~/.kube，然后运行：

-> # cd ~/.kube && mv k8s-xxx-kubeconfig.yaml config
-> # kubectl get nodes                                          
NAME                  STATUS   ROLES    AGE    VERSION
pool-7wa24lnka-v3sf   Ready    <none>   11m    v1.16.2
pool-7wa24lnka-v3sq   Ready    <none>   11m    v1.16.2
pool-7wa24lnka-v3sy   Ready    <none>   8m8s   v1.16.2

可以看到集群的状态是Ready

部署前先创建命名空间，防止污染：

-> # kubectl create namespace flask-test
namespace/flask-test created 
-> # kubectl get namespace
NAME              STATUS   AGE
default           Active   169m
flask             Active   30m
flask-test        Active   65s
kube-node-lease   Active   169m
kube-public       Active   169m
kube-system       Active   169m

部署单个 pod

编辑flask-pod.yaml文件如下：

apiVersion: v1
kind: Pod
metadata:
        name: flask-pod
        labels:
           app: flask-helloworld
spec:
        containers:
        - name:  flask
          image: registry.cn-hangzhou.aliyuncs.com/xxx/flask:v0
          ports:
          - containerPort: 5000

部署应用：

-> # kubectl apply -f flask-pod.yaml -n flask-test
pod/flask-pod created
-> # kubectl get pod -n flask-test
NAME        READY   STATUS    RESTARTS   AGE
flask-pod   1/1     Running   0          12s

转发端口并访问：

-> # kubectl port-forward pods/flask-pod 5000:5000 -n flask-test
Forwarding from 127.0.0.1:5000 -> 5000
Handling connection for 5000

-> %  curl http://127.0.0.1:5000
hello world!

删除 Pod:

-> # kubectl delete pod flask-pod -n flask-test
pod "flask-pod" deleted

部署 Deployment

编写flask-deployment.yaml文件

apiVersion: apps/v1
kind: Deployment
metadata:
    name: flask-dep
    labels:
        app: flask-helloworld
spec:
    replicas: 2
    selector:
        matchLabels:
          app: flask-helloworld
    template:
        metadata:
          labels:
            app: flask-helloworld
        spec:
            containers:
            - name:  flask
              image: 'registry.cn-hangzhou.aliyuncs.com/xxx/flask:v0'
              ports:
              - containerPort: 5000

部署 Deployment：

-> # kubectl apply -f flask-deployment.yaml -n flask-test
deployment.apps/flask-dep created
-> # kubectl get deploy -n flask-test
NAME        READY   UP-TO-DATE   AVAILABLE   AGE
flask-dep   2/2     2            2           12s
-> # kubectl get pod -n flask-test
NAME                         READY   STATUS    RESTARTS   AGE
flask-dep-56bcc4b6c5-44gkv   1/1     Running   0          25s
flask-dep-56bcc4b6c5-kkkvl   1/1     Running   0          25s

转发端口并访问：

-> # kubectl port-forward deployment/flask-dep 5000:5000 -n flask-test
Forwarding from 127.0.0.1:5000 -> 5000
Handling connection for 5000

-> %  curl http://127.0.0.1:5000
hello world!

不要删除Deployment，后面还要用。

部署负载均衡应用

编写flask-service.yaml：

apiVersion: v1
kind: Service
metadata:
  name: flask-svc
  labels:
    app: flask-helloworld
spec:
  type: LoadBalancer
  ports:
  - port: 80
    targetPort: 5000
    protocol: TCP
  selector:
    app: flask-helloworld

部署 LoadBalancer 负载均衡：

-> # kubectl apply -f flask-service.yaml -n flask-test
service/flask-svc created
-> # kubectl get service -n flask-test
NAME        TYPE           CLUSTER-IP     EXTERNAL-IP   PORT(S)        AGE
flask-svc   LoadBalancer   10.245.139.6   <pending>     80:32349/TCP   9s

等待约5分钟，负载均衡实现，对外暴露端口:

-> # kubectl get service -n flask-test   
NAME        TYPE           CLUSTER-IP     EXTERNAL-IP     PORT(S)        AGE
flask-svc   LoadBalancer   10.245.139.6   139.59.194.75   80:32349/TCP   4m23s
-> # curl 139.59.194.75
hello world!

删除 service

-> # kubectl delete service flask-svc -n flask-test   
service "flask-svc" deleted

部署结束。

参考：

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