Kubernetes CRD Operator 开发 系列一: client-go框架介绍

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# crd-demo.yaml
apiVersion: apiextensions.k8s.io/v1
kind: CustomResourceDefinition
metadata:
  # name 必须匹配下面的spec字段：<plural>.<group>  
  name: crontabs.stable.example.com
spec:
  # group 名用于 REST API 中的定义：/apis/<group>/<version>  
  group: stable.example.com
  # 列出自定义资源的所有 API 版本  
  versions:
  - name: v1beta1  # 版本名称，比如 v1、v2beta1 等等    
    served: true  # 是否开启通过 REST APIs 访问 `/apis/<group>/<version>/...`    
    storage: true # 必须将一个且只有一个版本标记为存储版本    
    schema:  # 定义自定义对象的声明规范      
      openAPIV3Schema:
        description: Define CronTab YAML Spec
        type: object
        properties:
          spec:
            type: object
            properties:
              cronSpec:
                type: string
              image:
                type: string
              replicas:
                type: integer
  # 定义作用范围：Namespaced（命名空间级别）或者 Cluster（整个集群）  
  scope: Namespaced
  names:
    # kind 是 singular 的一个驼峰形式定义，在资源清单中会使用    
    kind: CronTab
    # plural 名字用于 REST API 中的定义：/apis/<group>/<version>/<plural>    
    plural: crontabs
    # singular 名称用于 CLI 操作或显示的一个别名    
    singular: crontab
    # shortNames 相当于缩写形式    
    shortNames:
    - ct

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[root@master ~]# kubectl apply -f crd-demo.yaml
customresourcedefinition.apiextensions.k8s.io/crontabs.stable.example.com created

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# crd-crontab-demo.yaml
apiVersion: "stable.example.com/v1beta1"
kind: CronTab
metadata:
  name: my-new-cron-object
spec:
  cronSpec: "* * * * */5"
  image: my-awesome-cron-image

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[root@master ~]# kubectl apply -f crd-crontab-demo.yaml
crontab.stable.example.com/my-new-cron-object created

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$ cd go/src/github.com/peterliao96
$ mkdir builder-demo
$ cd builder-demo
# 开启 go modules
$ export GO111MODULE=on
$ export GOPROXY=https://goproxy.cn
$ kubebuilder init --domain ydzs.io --owner peterliao96 --repo github.com/peterliao96/builder-demo
# 创建一个新的 API（组/版本）为 “webapp/v1”，并在上面创建新的 Kind(CRD) “Guestbook”
$ kubebuilder create api --group webapp --version v1 --kind Guestbook

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// api/v1/guestbook_types.go
package v1

import (
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
)

// EDIT THIS FILE!  THIS IS SCAFFOLDING FOR YOU TO OWN!
// NOTE: json tags are required.  Any new fields you add must have json tags for the fields to be serialized.

// GuestbookSpec defines the desired state of Guestbook
type GuestbookSpec struct {
	// INSERT ADDITIONAL SPEC FIELDS - desired state of cluster
	// Important: Run "make" to regenerate code after modifying this file

	// Foo is an example field of Guestbook. Edit guestbook_types.go to remove/update
	Foo string `json:"foo,omitempty"`
}

// GuestbookStatus defines the observed state of Guestbook
type GuestbookStatus struct {
	// INSERT ADDITIONAL STATUS FIELD - define observed state of cluster
	// Important: Run "make" to regenerate code after modifying this file
}

//+kubebuilder:object:root=true
//+kubebuilder:subresource:status

// Guestbook is the Schema for the guestbooks API
type Guestbook struct {
	metav1.TypeMeta   `json:",inline"`
	metav1.ObjectMeta `json:"metadata,omitempty"`

	Spec   GuestbookSpec   `json:"spec,omitempty"`
	Status GuestbookStatus `json:"status,omitempty"`
}

//+kubebuilder:object:root=true

// GuestbookList contains a list of Guestbook
type GuestbookList struct {
	metav1.TypeMeta `json:",inline"`
	metav1.ListMeta `json:"metadata,omitempty"`
	Items           []Guestbook `json:"items"`
}

func init() {
	SchemeBuilder.Register(&Guestbook{}, &GuestbookList{})
}