Kubernetes 的基本使用方法

Kubernetes的基本使用方法

原则：使用YAML文件描述你要部署的API对象！

以部署Nginx静态站点为例，具体操作及内容如下

1.编写YAML文件

[root@kubernetes01 ~]# cat Nginx-staticwebsite.yaml 
apiVersion: apps/v1
kind: Deployment
Metadata:
  name: Nginx-staticwebsite
spec:
  selector:
    matchLabels: 
      app: Nginx
  replicas: 2
  template: 
    Metadata:
      labels:
        app: Nginx
    spec:
      containers: 
      - name: Nginx
        image: Nginx:1.9.1
        ports: 
        - containerPort: 80
        volumeMounts: 
        - mountPath: "/usr/share/Nginx/html" 
          name: Nginx-staticwebsite-vol
      volumes: 
      - name: Nginx-staticwebsite-vol
        hostPath:
          path: "/home/data/kubernetes/Nginx-staticwebsite"

2.YAML文件说明

apiVersion: apps/v1
kind: Deployment //指定了API对象的类型，Deployment是一个可以定义多副本应用的对象
Metadata: //API对象的标示，用来存放元数据
  name: Nginx-staticwebsite //定义元数据名
spec: //对象的独有定义
  selector: //选择器
    matchLabels: //匹配的标签
      app: Nginx //app名称
  replicas: 2 //定义副本数量
  template: //定义Pod的模版用来描述细节，需要理解Pod就是Kubernetes世界中的应用
    Metadata: //模版的元数据
      labels: //标签
        app: Nginx //app名称
    spec:
      containers: //Pod中只定义了一个容器
      - name: Nginx //名称
        image: Nginx:1.9.1 //镜像的名称
        ports: 
        - containerPort: 80 //容器监听的端口
        volumeMounts: //Pod中的容器声明自己挂载哪个Volume
        - mountPath: "/usr/share/Nginx/html" //定义容器的中的Volume的目录
          name: Nginx-staticwebsite-vol //Volume的名字
      volumes: //定义这个Pod声明的所有Volume显式定义
      - name: Nginx-staticwebsite-vol //Volume的名字
        hostPath:
          path: "/home/data/kubernetes/Nginx-staticwebsite" //显式定义，Volume挂载的宿主机目录
      
      //隐式定义，我们没有用到
      volumes: 定义这个Pod声明的所有卷
        - name: Nginx-vol
          emptyDir: {} 隐式定义

3.操作YAML文件

1.运行这个YAML文件
kubelctl create -f Nginx-staticwebsite.yaml

2.GET指定的API对象
[root@kubernetes01 ~]# kubectl  get pods -l app=Nginx
NAME                                READY   STATUS    RESTARTS   AGE
Nginx-staticwebsite-8479f8997f-2mh4j   1/1     Running   0          153m
Nginx-staticwebsite-8479f8997f-s526z   1/1     Running   0          153m

3.查看API对象的细节
[root@kubernetes01 ~]# kubectl describe pod Nginx-staticwebsite-8479f8997f-2mh4j
Name:               Nginx-staticwebsite-8479f8997f-2mh4j
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kubernetes09/10.5.0.219
Start Time:         Mon, 11 Mar 2019 11:35:53 +0800
Labels:             app=Nginx
                    pod-template-hash=8479f8997f
Annotations:        <none>
Status:             Running
IP:                 10.39.0.2
Controlled By:      replicaset/Nginx-staticwebsite-8479f8997f
Containers:
  Nginx:
    Container ID:   docker://08e49e4a3f253e317b7e4a9603e9398bca9f1762daa7dd10ddf885e4e20f2078
    Image:          Nginx:1.9.1
    Image ID:       docker-pullable://Nginx@sha256:2f68b99bc0d6d25d0c56876b924ec20418544ff28e1fb89a4c27679a40da811b
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Mon, 11 Mar 2019 11:36:09 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /usr/share/Nginx/html from Nginx-staticwebsite-vol (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-8j8dl (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  Nginx-staticwebsite-vol:
    Type:          HostPath (bare host directory volume)
    Path:          /home/data/kubernetes/Nginx-staticwebsite
    HostPathType:  
  default-token-8j8dl:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-8j8dl
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:          <none>

4.尝试更新镜像
修改YAML文件中的Nginx的镜像版本
[root@kubernetes01 ~]# cat Nginx-staticwebsite.yaml  | grep "image"
        image: Nginx:1.9.2
[root@kubernetes01 ~]# kubectl apply -f Nginx-staticwebsite.yaml
[root@kubernetes01 ~]# kubectl get pods  -l app=Nginx
NAME                                   READY   STATUS              RESTARTS   AGE
Nginx-deployment-7f987f7889-8tbbt      1/1     Running             0          3h23m
Nginx-deployment-7f987f7889-rh8xc      1/1     Running             0          3h23m
Nginx-staticwebsite-648bc64544-snjpg   0/1     ContainerCreating   0          23s
Nginx-staticwebsite-8479f8997f-2mh4j   1/1     Running             0          160m
Nginx-staticwebsite-8479f8997f-s526z   1/1     Running             0          160m
[root@kubernetes01 ~]# kubectl describe pod Nginx-staticwebsite-648bc64544-snjpg
Name:               Nginx-staticwebsite-648bc64544-snjpg
Namespace:          default
Priority:           0
PriorityClassName:  <none>
Node:               kubernetes05/10.5.0.210
Start Time:         Mon, 11 Mar 2019 14:15:36 +0800
Labels:             app=Nginx
                    pod-template-hash=648bc64544
Annotations:        <none>
Status:             Running
IP:                 10.45.0.3
Controlled By:      replicaset/Nginx-staticwebsite-648bc64544
Containers:
  Nginx:
    Container ID:   docker://b3fb6b0aa095990482027158c4bce84dbe023f2ae7f2ccb6b4d521d3274a93cf
    Image:          Nginx:1.9.2
    Image ID:       docker-pullable://Nginx@sha256:7ffb2ccf2de82b0afeee46ae9d7542e9643587a8d4dbe2901cf466369e3c10f5
    Port:           80/TCP
    Host Port:      0/TCP
    State:          Running
      Started:      Mon, 11 Mar 2019 14:16:00 +0800
    Ready:          True
    Restart Count:  0
    Environment:    <none>
    Mounts:
      /usr/share/Nginx/html from Nginx-staticwebsite-vol (rw)
      /var/run/secrets/kubernetes.io/serviceaccount from default-token-8j8dl (ro)
Conditions:
  Type              Status
  Initialized       True 
  Ready             True 
  ContainersReady   True 
  PodScheduled      True 
Volumes:
  Nginx-staticwebsite-vol:
    Type:          HostPath (bare host directory volume)
    Path:          /home/data/kubernetes/Nginx-staticwebsite
    HostPathType:  
  default-token-8j8dl:
    Type:        Secret (a volume populated by a Secret)
    SecretName:  default-token-8j8dl
    Optional:    false
QoS Class:       BestEffort
Node-Selectors:  <none>
Tolerations:     node.kubernetes.io/not-ready:NoExecute for 300s
                 node.kubernetes.io/unreachable:NoExecute for 300s
Events:
  Type    Reason     Age   From                   Message
  ----    ------     ----  ----                   -------
  normal  Scheduled  70s   default-scheduler      Successfully assigned default/Nginx-staticwebsite-648bc64544-snjpg to kubernetes05
  normal  Pulling    69s   kubelet, kubernetes05  pulling image "Nginx:1.9.2"
  normal  Pulled     46s   kubelet, kubernetes05  Successfully pulled image "Nginx:1.9.2"
  normal  Created    46s   kubelet, kubernetes05  Created container
  normal  Started    46s   kubelet, kubernetes05  Started container
可以看到Events中的信息！这块信息很重要因为我们可以用来排错！

5.静态网站访问
[root@kubernetes01 ~]# curl 10.35.0.3
Nginx static website!
[root@kubernetes01 ~]# curl 10.39.0.2
Nginx static website!

4.总结

通过对Kubenetes的基本操作和体验，不难发现，YAML文件我们可以做版本化管理，当热这也是发布应用的最基本操作！你GET到了吗？朋友