Kubenetes 资源清单定义入门

Kubernetes 常用资源:

我将它们简单的分类为以下几种资源对象：

类别	名称
工作负载型资源对象	Pod、ReplicaSet、Replication Controller、Deployment、StatefulSet、DaemonSet、Job、CronJob
服务发现及负载均衡	Service、Ingress
配置与存储	Volume、Persistent Volume、CSl 、 configmap、secret 、DownwardAPI
集群资源	Namespace、Node、Role、ClusterRole、RoleBinding、ClusterRoleBinding
元数据资源	HPA、PodTemplate、LimitRange

利用命令获取一个Pod的资源清单内容并输出为yaml格式：

[root@master app]# kubectl get pods nginx-deployment-67594d6bf6-8w947 -n kube-system -o yaml

apiVersion: v1     # K8S API版本，应该由两部分组成：group/version，group省略表示默认为core 
kind: Pod           # 资源类别： Pod、Deployment、Service等等
metadata:          # 资源元数据
  creationTimestamp: 2018-09-27T06:29:25Z
  generateName: nginx-deployment-67594d6bf6-
  labels:
    app: nginx
    pod-template-hash: "2315082692"
  name: nginx-deployment-67594d6bf6-8w947
  namespace: kube-system
  ownerReferences:
  - apiVersion: apps/v1
    blockOwnerDeletion: true
    controller: true
    kind: ReplicaSet
    name: nginx-deployment-67594d6bf6
    uid: ceebf775-acef-11e8-b183-d8490b8af3ae
  resourceVersion: "5070139"
  selfLink: /api/v1/namespaces/kube-system/pods/nginx-deployment-67594d6bf6-8w947
  uid: adca27df-c21e-11e8-8dd6-d8490b8af3ae
spec:     # specifications, 资源规格。（定义资源对象期望的状态），这个是最重要的字段，用于规定接下来要创建的资源对象应该拥有的特性。然后依靠控制器确保这些特性能够被满足。
  containers:
  - image: nginx:1.7.9
    imagePullPolicy: IfNotPresent
    name: nginx
    ports:
    - containerPort: 80
      protocol: TCP
    resources: {}
    terminationMessagePath: /dev/termination-log
    terminationMessagePolicy: File
  dnsPolicy: ClusterFirst
  nodeName: node1
  restartPolicy: Always
  schedulerName: default-scheduler
  securityContext: {}
  terminationGracePeriodSeconds: 30
status:       # 用于显示这个资源对象当前的状态，这个字段是只读的。
  conditions:
  - lastProbeTime: null
    lastTransitionTime: 2018-09-27T06:30:35Z
    status: "True"
    type: Initialized
  - lastProbeTime: null
    lastTransitionTime: 2018-09-27T06:30:37Z
    status: "True"
    type: Ready
  - lastProbeTime: null
    lastTransitionTime: null
    status: "True"
    type: ContainersReady
  - lastProbeTime: null
    lastTransitionTime: 2018-09-27T06:29:25Z
    status: "True"
    type: PodScheduled
  containerStatuses:
  - containerID: docker://3e1b5e5f2590bf50d04c98540c937b3d3bf9ea4ffb6a5a08979ac0914f161e49
    image: nginx:1.7.9
    imageID: docker-pullable://nginx@sha256:e3456c851a152494c3e4ff5fcc26f240206abac0c9d794affb40e0714846c451
    lastState: {}
    name: nginx
    ready: true
    restartCount: 0
    state:
      running:
        startedAt: 2018-09-27T06:30:36Z
  hostIP: 172.19.0.204
  phase: Running
  podIP: 10.1.35.2
  qosClass: BestEffort
  startTime: 2018-09-27T06:30:35Z

缺少部分：

tolerations:        # 容忍度，能够容忍哪些污点
- 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-rqmtb
  secret:
    defaultMode: 420
    secretName: default-token-rqmtb

创建资源清单的方法：

1 2	`apiserver 仅接受JOSN格式的资源定义 yaml格式提供配置清单，apiserver自动转成json格式，然后在提交`

大部分资源的配置清单：

apiVersion: 格式：group/version 查看 kubectl apiversion
kind: Pod Replicaset Deployments ...
metadata: name namespace labels annotations
spec: 定义用户期望状态 disired state
status: 定义当前状态 current state 该字段由kubenetes集群维护；

配置清单格式：

apiVersion: v1     # kubectl api-versions（查看命令）

kind: 资源类别（Pod Replicaset Deployments ...）

metadata: 元数据
    name: 资源名称
    namespace: 名称空间
    labels: 标签，键值数据。数据大小有限制。
    annotations: 注解，也是键值数据，但是它的数据没有大小限制。

spec: 期望的状态，disired state，由用户定义，最重要。每种资源支持的字段不一样。
status: 当前状态，current state, 本字段由K8S集群维护。

通过命令查看如何定义资源 (标有 required 意味是必填项)

kubectl explain 命令语法：

1	`kubectl explain RESOURCE [options]`

示例：

#获取pods资源及其字段的文档
kubectl explain pods

#获取pods资源的特定字段的文档（只要字段后面有<Object>关键字就表示有二级字段）
kubectl explain pods.spec.containers

[root@master app]# kubectl explain pod             查看如何定义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/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/api-conventions.md#types-kinds

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

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

注释：map类型的不需要在前面加“-”线，list类型的需要在前面加“-”线

定义一个简单的资源清单：

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ye
  namespace: kube-system
  labels:
    app: myapp              #deployment的labels
spec:
    replicas: 5
    selector:
      matchLabels:
        app: frontend
    template:
      metadata:
        labels:
          app: frontend      #pods的labels
      spec:
        containers:
        - name: nginx
          image: nginx:1.7.9

kubectl create 命令:

描述：

通过配置文件名或stdin创建一个集群资源对象。支持JSON和YAML格式的文件。

语法：

1	`kubectl create -f FILENAME [options]`

示例:

通过pod.json文件创建资源。
kubectl create -f pod.json

根据docker-registry.yaml文件创建资源。
kubectl create -f docker-registry.yaml

Kubenetes 资源清单定义入门

https://system51.github.io/2019/08/23/Kubenetes-Resource/

作者

Mr.Ye

发布于

2019年8月23日

许可协议

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