Kerbernetes的Pod资源清单配置基础
作者：尹正杰
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一.资源对象管理方式
kubectl的命令可分为三类:
陈述式命令(Imperative Commands)
陈述式对象配置(Imperative Object Configuration)
声明式对象配置(Declarative Object Configuration)
第一种方式即此前用到的run,expose,delete和get等命令，它们直接作用于kubernetes系统上的活动对象，简单易用,但不是支持代码复用，修改复审及审计日志等功能，这些功能的实现通常要依赖于资源配置文件中，这些文件也被称为资源清单。
1>.陈述式命令创建名称空间案例(执行命令的方式缺点就是每次都得去敲,复用性极差,因此它相比陈述式，声明式对象配置压根就没有复用性)
[root@master200.yinzhengjie.org.cn ~]# kubectl get namespace #查看名称空间 NAME STATUS AGE default Active 9h kube-node-lease Active 9h kube-public Active 9h kube-system Active 9h [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl get ns #也是查看名称空间，只不过这里是简写形式而已 NAME STATUS AGE default Active 9h kube-node-lease Active 9h kube-public Active 9h kube-system Active 9h [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl create namespace operation #创建一个叫做"operation"的名称空间 namespace/operation created [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl create ns development namespace/development created [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl create ns testing namespace/testing created [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl get ns NAME STATUS AGE default Active 9h development Active 38s kube-node-lease Active 9h kube-public Active 9h kube-system Active 9h operation Active 65s testing Active 3s [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]#
2>.陈述式对象配置创建名称空间案例(重复创建时会报错,生产环境不推荐使用)
[root@master200.yinzhengjie.org.cn ~]# mkdir -pv /yinzhengjie/data/k8s/manifests/basic mkdir: created directory ‘/yinzhengjie/data’ mkdir: created directory ‘/yinzhengjie/data/k8s’ mkdir: created directory ‘/yinzhengjie/data/k8s/manifests’ mkdir: created directory ‘/yinzhengjie/data/k8s/manifests/basic’ [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# cd /yinzhengjie/data/k8s/manifests/basic/ [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# vim develop-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# cat develop-ns.yaml apiVersion: v1 kind: Namespace metadata: name: develop [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl get ns NAME STATUS AGE default Active 17h kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# ll total 4 -rw-r--r-- 1 root root 59 Feb 5 12:53 develop-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl create -f develop-ns.yaml #使用陈述式对象配置创建名称空间 namespace/develop created [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# ll total 4 -rw-r--r-- 1 root root 59 Feb 5 12:53 develop-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl get ns NAME STATUS AGE default Active 17h develop Active 8s kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl create -f develop-ns.yaml #由于咱们定义的"develop"名称空间已经存在，因此给咱们抛出异常 Error from server (AlreadyExists): error when creating "develop-ns.yaml": namespaces "develop" already exists [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]#
3>.声明式对象配置创建名称空间案例(重复创建时并不会报错)
[root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# cp develop-ns.yaml production-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# vim production-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# cat production-ns.yaml apiVersion: v1 kind: Namespace metadata: name: production [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# ll total 8 -rw-r--r-- 1 root root 59 Feb 5 12:53 develop-ns.yaml -rw-r--r-- 1 root root 62 Feb 5 12:55 production-ns.yaml [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl get ns NAME STATUS AGE default Active 17h develop Active 2m26s kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl get namespace NAME STATUS AGE default Active 17h develop Active 2m35s kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl apply -f production-ns.yaml #使用声明式对象配置创建名称空间 namespace/production created [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl get namespace NAME STATUS AGE default Active 17h develop Active 2m57s kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h production Active 2s [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]# kubectl apply -f production-ns.yaml #重复创建同一个名称空间时并不会报错，而是友好的提示咱们没有发生任何改变。 namespace/production unchanged [root@master200.yinzhengjie.org.cn /yinzhengjie/data/k8s/manifests/basic]#
二.使用声明式对象配置创建pod(在一个pod中创建一个容器)
查看官方的参数参考文档: https://kubernetes.io/docs/reference/generated/kubernetes-api/v1.17/#pod-v1-core
1>.使用"--export"选项将一个容器的创建作为模板导出(注意，该参数已经被废弃了，生产环境中尽量避免使用它，推荐大家使用Helm去管理)
[root@master200.yinzhengjie.org.cn ~]# kubectl get pods NAME READY STATUS RESTARTS AGE mynginx-677d85dbd5-gkdb6 1/1 Running 0 5h12m mynginx-677d85dbd5-vk5p5 1/1 Running 0 5h39m [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]# kubectl get pods mynginx-677d85dbd5-gkdb6 -o yaml --export > /yinzhengjie/data/k8s/manifests/basic/pod-demo.yaml Flag --export has been deprecated, This flag is deprecated and will be removed in future. [root@master200.yinzhengjie.org.cn ~]# [root@master200.yinzhengjie.org.cn ~]#
[root@master200.yinzhengjie.org.cn ~]# cat /yinzhengjie/data/k8s/manifests/basic/pod-demo.yaml apiVersion: v1 kind: Pod metadata: creationTimestamp: null generateName: mynginx-677d85dbd5- labels: app: mynginx pod-template-hash: 677d85dbd5 ownerReferences: - apiVersion: apps/v1 blockOwnerDeletion: true controller: true kind: ReplicaSet name: mynginx-677d85dbd5 uid: c5ff8e76-768b-4673-8df3-b5d3246a929d selfLink: /api/v1/namespaces/default/pods/mynginx-677d85dbd5-gkdb6 spec: containers: - image: nginx:1.14-alpine imagePullPolicy: IfNotPresent name: nginx resources: {} terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-4jpjf readOnly: true dnsPolicy: ClusterFirst enableServiceLinks: true nodeName: node201.yinzhengjie.org.cn priority: 0 restartPolicy: Always schedulerName: default-scheduler securityContext: {} serviceAccount: default serviceAccountName: default terminationGracePeriodSeconds: 30 tolerations: - effect: NoExecute key: node.kubernetes.io/not-ready operator: Exists tolerationSeconds: 300 - effect: NoExecute key: node.kubernetes.io/unreachable operator: Exists tolerationSeconds: 300 volumes: - name: default-token-4jpjf secret: defaultMode: 420 secretName: default-token-4jpjf status: phase: Pending qosClass: BestEffort [root@master200.yinzhengjie.org.cn ~]#