### 歡迎訪問我的GitHub
> 這裡分類和彙總了欣宸的全部原創(含配套原始碼)：[https://github.com/zq2599/blog_demos](https://github.com/zq2599/blog_demos)

### 本篇概覽
- 本文是《k8s自定義controller三部曲》的終篇，前面的章節中，我們建立了CRD，再透過自動生成程式碼的工具將controller所需的informer、client等依賴全部準備好，到了本章，就該編寫controller的程式碼了，也就是說，現在已經能監聽到Student物件的增刪改等事件，接下來就是根據這些事件來做不同的事情，滿足個性化的業務需求；

### 三部曲所有文章連結
1. [《k8s自定義controller三部曲之一:建立CRD（Custom Resource Definition）》](https://blog.csdn.net/boling_cavalry/article/details/88917818)；
2. [《k8s自定義controller三部曲之二:自動生成程式碼》](https://blog.csdn.net/boling_cavalry/article/details/88924194)；
3. [《k8s自定義controller三部曲之三：編寫controller程式碼》](https://blog.csdn.net/boling_cavalry/article/details/88934063)；

### 原始碼下載
- 接下來詳細講述應用的編碼過程，如果您不想自己寫程式碼，也可以在GitHub下載完整的應用原始碼，地址和連結資訊如下表所示：

| 名稱      |   連結 |   備註|
| :-------- | :----| :----|
| 專案主頁| https://github.com/zq2599/blog_demos | 該專案在GitHub上的主頁 |
| git倉庫地址(https)| https://github.com/zq2599/blog_demos.git | 該專案原始碼的倉庫地址，https協議 |
| git倉庫地址(ssh)| git@github.com:zq2599/blog_demos.git | 該專案原始碼的倉庫地址，ssh協議 |

- 這個git專案中有多個資料夾，本章原始碼在k8s_customize_controller這個資料夾下，如下圖紅框所示：
![在這裡插入圖片描述](https://img-blog.csdnimg.cn/20190401000525549.jpg?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly94aW5jaGVuLmJsb2cuY3Nkbi5uZXQ=,size_16,color_FFFFFF,t_70)

### 開始實戰
- 回顧一下，上一章透過自動程式碼生成工具生成程式碼後，原始碼目錄的內容如下：

```shell
[root@golang k8s_customize_controller]# tree
.
└── pkg
    ├── apis
    │   └── bolingcavalry
    │       ├── register.go
    │       └── v1
    │           ├── doc.go
    │           ├── register.go
    │           ├── types.go
    │           └── zz_generated.deepcopy.go
    └── client
        ├── clientset
        │   └── versioned
        │       ├── clientset.go
        │       ├── doc.go
        │       ├── fake
        │       │   ├── clientset_generated.go
        │       │   ├── doc.go
        │       │   └── register.go
        │       ├── scheme
        │       │   ├── doc.go
        │       │   └── register.go
        │       └── typed
        │           └── bolingcavalry
        │               └── v1
        │                   ├── bolingcavalry_client.go
        │                   ├── doc.go
        │                   ├── fake
        │                   │   ├── doc.go
        │                   │   ├── fake_bolingcavalry_client.go
        │                   │   └── fake_student.go
        │                   ├── generated_expansion.go
        │                   └── student.go
        ├── informers
        │   └── externalversions
        │       ├── bolingcavalry
        │       │   ├── interface.go
        │       │   └── v1
        │       │       ├── interface.go
        │       │       └── student.go
        │       ├── factory.go
        │       ├── generic.go
        │       └── internalinterfaces
        │           └── factory_interfaces.go
        └── listers
            └── bolingcavalry
                └── v1
                    ├── expansion_generated.go
                    └── student.go

21 directories, 27 files
```

- 本章要編寫的第一個go檔案就是controller.go，在k8s_customize_controller目錄下建立controller.go，程式碼內容如下：

```go
package main

import (
	"fmt"
	"time"

"github.com/golang/glog"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/util/runtime"
	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
	"k8s.io/apimachinery/pkg/util/wait"
	"k8s.io/client-go/kubernetes"
	"k8s.io/client-go/kubernetes/scheme"
	typedcorev1 "k8s.io/client-go/kubernetes/typed/core/v1"
	"k8s.io/client-go/tools/cache"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/workqueue"

bolingcavalryv1 "github.com/zq2599/k8s-controller-custom-resource/pkg/apis/bolingcavalry/v1"
	clientset "github.com/zq2599/k8s-controller-custom-resource/pkg/client/clientset/versioned"
	studentscheme "github.com/zq2599/k8s-controller-custom-resource/pkg/client/clientset/versioned/scheme"
	informers "github.com/zq2599/k8s-controller-custom-resource/pkg/client/informers/externalversions/bolingcavalry/v1"
	listers "github.com/zq2599/k8s-controller-custom-resource/pkg/client/listers/bolingcavalry/v1"
)

const controllerAgentName = "student-controller"

const (
	SuccessSynced = "Synced"

MessageResourceSynced = "Student synced successfully"
)

// Controller is the controller implementation for Student resources
type Controller struct {
	// kubeclientset is a standard kubernetes clientset
	kubeclientset kubernetes.Interface
	// studentclientset is a clientset for our own API group
	studentclientset clientset.Interface

studentsLister listers.StudentLister
	studentsSynced cache.InformerSynced

workqueue workqueue.RateLimitingInterface

recorder record.EventRecorder
}

// NewController returns a new student controller
func NewController(
	kubeclientset kubernetes.Interface,
	studentclientset clientset.Interface,
	studentInformer informers.StudentInformer) *Controller {

utilruntime.Must(studentscheme.AddToScheme(scheme.Scheme))
	glog.V(4).Info("Creating event broadcaster")
	eventBroadcaster := record.NewBroadcaster()
	eventBroadcaster.StartLogging(glog.Infof)
	eventBroadcaster.StartRecordingToSink(&typedcorev1.EventSinkImpl{Interface: kubeclientset.CoreV1().Events("")})
	recorder := eventBroadcaster.NewRecorder(scheme.Scheme, corev1.EventSource{Component: controllerAgentName})

controller := &Controller{
		kubeclientset:    kubeclientset,
		studentclientset: studentclientset,
		studentsLister:   studentInformer.Lister(),
		studentsSynced:   studentInformer.Informer().HasSynced,
		workqueue:        workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), "Students"),
		recorder:         recorder,
	}

glog.Info("Setting up event handlers")
	// Set up an event handler for when Student resources change
	studentInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
		AddFunc: controller.enqueueStudent,
		UpdateFunc: func(old, new interface{}) {
			oldStudent := old.(*bolingcavalryv1.Student)
			newStudent := new.(*bolingcavalryv1.Student)
			if oldStudent.ResourceVersion == newStudent.ResourceVersion {
                //版本一致，就表示沒有實際更新的操作，立即返回
				return
			}
			controller.enqueueStudent(new)
		},
		DeleteFunc: controller.enqueueStudentForDelete,
	})

return controller
}

//在此處開始controller的業務
func (c *Controller) Run(threadiness int, stopCh  [學習路上，你不孤單，欣宸原創一路相伴...](http://blog.itpub.net/70017844/)

k8s自定義controller三部曲之三：編寫controller程式碼

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