Kubenetes 资源清单定义入门

Kubernetes 常用资源

• 资源  对象

1. 工作负载型资源对象（workload）: Pod  Replicaset  ReplicationController  Deployments StatefulSets Daemonset Job CronJob
2. 服务发现及负载均衡： Service  Ingress
3. 配置与存储：Volumes CSl  configmap  secret
4. 集群资源：Namespace Node Role ClusterRole  RoleBinding  ClusterRoleBinding
5. 元数据资源：HPA PodTemplate LimitRang

创建资源清单的方法

• 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；

通过 yaml写一个简单的 pod应用

$ vim my-demo.yaml 

apiVersion: v1
kind: Pod
metadata:
  name: my-demo
  namespace: default
  labels:
    name: myapp
    tier: appfront
spec:
  containers:
  - name: myapp
    image: ikubernetes/myapp:v1
  - name: busybox
    image: busybox
    command:
    - "/bin/sh"
    - "-c"
    - "sleep 3600"

$ kubectl apply -f my-demo.yaml

通过 kubectl  describe pods my-demo 查看集群信息

通过命令查看如何定义资源  (标有 required  意味是必填项)

$ kubectl  explain deployment
DESCRIPTION:
DEPRECATED - This group version of Deployment is deprecated by apps/v1beta2/Deployment. See the release notes for more information. Deployment enables declarative updates for Pods and ReplicaSets.

FIELDS:
   status       <Object>
     Most recently observed status of the Deployment.

   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 metadata.

   spec <Object>
     Specification of the desired behavior of the Deployment.

$  kubectl  explain deployment.spec

RESOURCE: spec <Object>

DESCRIPTION:
     Specification of the desired behavior of the Deployment.

    DeploymentSpec is the specification of the desired behavior of the Deployment.

FIELDS:
   paused       <boolean>
     Indicates that the deployment is paused and will not be processed by the
     deployment controller.

   revisionHistoryLimit <integer>
     The number of old ReplicaSets to retain to allow rollback. This is a
     pointer to distinguish between explicit zero and not specified.

   template     <Object> -required-
     Template describes the pods that will be created.

   rollbackTo   <Object>
     DEPRECATED. The config this deployment is rolling back to. Will be cleared
     after rollback is done.

   selector     <Object>
     Label selector for pods. Existing ReplicaSets whose pods are selected by
     this will be the ones affected by this deployment.

   strategy     <Object>
     The deployment strategy to use to replace existing pods with new ones.
......