Kubernetes进阶 -- 编写资源清单（一）

k8s的资源清单采用标记性语言，写起来是有一定格式的，所以只要记住了格式，写起来是很easy的。

生命热力٩( 'ω' )و

544人浏览 · 2020-06-19 16:01:33

生命热力٩( 'ω' )و · 2020-06-19 16:01:33 发布

资源清单格式：

采用标记性语言.

格式如下:
• apiVersion: group/version ：指明api资源属于哪个群组和版本,同一个组可以有多个版本

[root@server2 manifest]# kubectl api-versions		//查询命令
admissionregistration.k8s.io/v1			//前面是群组，后面是版本
admissionregistration.k8s.io/v1beta1
apiextensions.k8s.io/v1
apiextensions.k8s.io/v1beta1
apiregistration.k8s.io/v1
apiregistration.k8s.io/v1beta1
apps/v1
。。。	
v1				里面有很多，一般情况下，我们写v1 就行了

kind ：标记创建的资源类型,k8s主要支持以下资源类别
- Pod,ReplicaSet,Deployment,StatefulSet,DaemonSet,Job,Cronjob
metadata: 元数据
- name: 对像名称
- namespace: 对象属于哪个命名空间,默认是default
- labels: 指定资源标签,标签是一种键值数据
spec: 定义目标资源的期望状态

我们可以使用 kubectl explain 来查询帮助文档：
例如：

[root@server2 manifest]# kubectl explain pod
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

FIELDS:
   apiVersion	<string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind	<string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata	<Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   spec	<Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

   status	<Object>
     Most recently observed status of the pod. This data may not be up to date.
     Populated by the system. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

更具体的：
[root@server2 manifest]# kubectl explain pod.spec
KIND:     Pod
VERSION:  v1

RESOURCE: spec <Object>

DESCRIPTION:
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

     PodSpec is a description of a pod.

FIELDS:
   automountServiceAccountToken	<boolean>
     AutomountServiceAccountToken indicates whether a service account token
     should be automatically mounted.

   containers	<[]Object> -required-		# 加required的是必须要有的
     List of containers belonging to the pod. Containers cannot currently be
     added or removed. There must be at least one container in a Pod. Cannot be
     updated.

资源清单中必须存在字段
k8s主要对象

在这里插入图片描述

k8s 常用的额外参数

在这里插入图片描述

我们先清除之前的一些操作数据：

[root@server2 manifest]# kubectl delete svc myapp 
service "myapp" deleted
[root@server2 manifest]# kubectl delete pod demo 
pod "demo" deleted
[root@server2 manifest]# kubectl delete deployments.apps myapp 
deployment.apps "myapp" deleted

[root@server2 ~]# cd manifest/		# 创建清单目录
[root@server2 manifest]# cd ..
[root@server2 manifest]#

创建自主式pod清单

[root@server2 manifest]# vim pod.yml 
[root@server2 manifest]# cat pod.yml 
apiVersion: v1
kind: Pod
metadata:
  name: myapp
#  namespace: default		# 可以不写，默认指定default 命名空间
#  labels:			# 标签页可以不写
spec:
  containers:
    - name: myapp
      image: myapp:v1
[root@server2 manifest]# kubectl create -f pod.yml 
pod/myapp created
[root@server2 manifest]# kubectl get pod -o wide
NAME    READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
myapp   1/1     Running   0          67s   10.244.1.31   server3   <none>           <none>
[root@server2 manifest]# curl 10.244.1.31
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>

最简单的一个pod资源清单就创建好了。

删除：

[root@server2 manifest]# kubectl delete -f pod.yml 
pod "myapp" deleted
[root@server2 manifest]# kubectl get pod -o wide
No resources found in default namespace.

更新：

[root@server2 manifest]# vim pod.yml 
spec:
  containers:
    - name: myapp
      image: myapp:v2		//这里替换为v2
[root@server2 manifest]# kubectl create -f pod.yml 
pod/myapp created
[root@server2 manifest]# kubectl get pod -o wide
NAME    READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
myapp   1/1     Running   0          9s    10.244.1.32   server3   <none>           <none>
[root@server2 manifest]# curl 10.244.1.32
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>
[root@server2 manifest]# kubectl delete -f pod.yml 
pod "myapp" deleted

生产环境中不加控制器的pod 很少见

加控制器的清单

[root@server2 manifest]# vim pod2.yml
[root@server2 manifest]# cat pod2.yml 
apiVersion: apps/v1
kind: Deployment
metadata:
  # Unique key of the Deployment instance
  name: deployment-example
spec:
  # 3 Pods should exist at all times.
  replicas: 3		//加了控制器，三个副本
  selector:			//选择器，控制器选择指定的pod进行控管
    matchLabels:	//通过匹配标签控管
      app: nginx	
  template:			//模板，通过模板创建容器，因为我们有三个副本
    metadata:
      labels:
        # Apply this label to pods and default
        # the Deployment label selector to this value
        app: nginx		//创建一个标签
    spec:
      containers:
      - name: nginx		
        # Run this image
        image: myapp:v1

带控制器的清单我们建议用apply 运行：
[root@server2 manifest]# kubectl apply -f pod2.yml 
get podeployment.apps/deployment-example created
[root@server2 manifest]# kubectl get pods --show-labels 
NAME                                  READY   STATUS    RESTARTS   AGE   LABELS
deployment-example-7d5c95894c-8wmp6   1/1     Running   0          31s   app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-kjm48   1/1     Running   0          31s   app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-rwlmf   1/1     Running   0          31s   app=nginx,pod-template-hash=7d5c95894c

拉伸

[root@server2 manifest]# vim pod2.yml 
spec:
  # 3 Pods should exist at all times.
  replicas: 6		// 改为6
[root@server2 manifest]# kubectl apply -f pod2.yml 
deployment.apps/deployment-example configured
[root@server2 manifest]# kubectl get pods --show-labels 
NAME                                  READY   STATUS              RESTARTS   AGE   LABELS
deployment-example-7d5c95894c-7wmwl   0/1     ContainerCreating   0          1s    app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-88cqt   0/1     ContainerCreating   0          1s    app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-8wmp6   1/1     Running             0          86s   app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-kjm48   1/1     Running             0          86s   app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-q4vfw   0/1     ContainerCreating   0          1s    app=nginx,pod-template-hash=7d5c95894c
deployment-example-7d5c95894c-rwlmf   1/1     Running             0          86s   app=nginx,pod-template-hash=7d5c95894c

滚动更新

[root@server2 manifest]# kubectl get pods -o wide
NAME                                  READY   STATUS    RESTARTS   AGE     IP            NODE      NOMINATED NODE   READINESS GATES
deployment-example-7d5c95894c-7wmwl   1/1     Running   0          88s     10.244.1.37   server3   <none>           <none>
...
[root@server2 manifest]# curl 10.244.1.37
Hello MyApp | Version: v1 | <a href="hostname.html">Pod Name</a>

[root@server2 manifest]# vim pod2.yml 
      - name: nginx		
        # Run this image
        image: myapp:v2			//镜像换成v2
[root@server2 manifest]# kubectl apply -f pod2.yml 
deployment.apps/deployment-example configured 
[root@server2 manifest]# kubectl get pods -o wide
NAME                                 READY   STATUS    RESTARTS   AGE   IP            NODE      NOMINATED NODE   READINESS GATES
deployment-example-86774dbbb-27mvb   1/1     Running   0          41s   10.244.2.15   server4   <none>           <none>
deployment-example-86774dbbb-5tpvf   1/1     Running   0          48s   10.244.2.12   server4   <none>           <none>
deployment-example-86774dbbb-b65c2   1/1     Running   0          47s   10.244.2.13   server4   <none>           <none>
deployment-example-86774dbbb-mx7kz   1/1     Running   0          41s   10.244.2.14   server4   <none>           <none>
deployment-example-86774dbbb-pwwmm   1/1     Running   0          48s   10.244.1.38   server3   <none>           <none>
deployment-example-86774dbbb-tjcd4   1/1     Running   0          43s   10.244.1.39   server3   <none>           <none>
[root@server2 manifest]# curl 10.244.2.15
Hello MyApp | Version: v2 | <a href="hostname.html">Pod Name</a>

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