一、概念

在了解operator之前，我也是一臉蒙蔽。這玩意是啥，沒見書上提到過。后來知道了 就是一個腳手架，在我們開發自定義資源的時候，operator能夠幫我們把我們需要的一些文件都準備好，包括CRD的yaml文件、ControllerManager的go文件等等。再詳細的原理，我就不貼圖片了，大家自己去找吧，反正網上很多相關資料。

二、安裝operator

我的本地環境是windows，一開始是嘗試的clone代碼到本地編譯的，后來試了幾次都有問題，官方也說他們沒有嘗試過windows環境的編譯，所以也不知道出了什么問題。所以跑了一個新的虛擬機。

https://blog.csdn.net/leehomjan/article/details/90735103

參考這篇文章吧環境搭好了。文章中的operator-sdk版本是RELEASE_VERSION=v0.8.0。我建議用RELEASE_VERSION=v0.15.0，不要用最新的v1.0也不要用什么v0.19.0之類的。因為這東西一直在更新，差一個版本差別好大。然后開發的流程是參考的這個。

https://www.bilibili.com/video/BV1zE411j7ky

這個視頻中就是v0.15.0，如果不是這個版本到時候會昏頭轉向。

三、創建項目和創建CRD

創建項目：

operator-sdk new imoocpod-operator --skip-validation=true --repo=github.com/imooc-com/imoocpod-operator

新增api

operator-sdk add api --api-version=k8s.imooc.com/v1alpha1 --kind=ImoocPod

新增controller

operator-sdk add controller --api-version=k8s.imooc.com/v1alpha1 --kind=ImoocPod

完成后代碼如下

.
|-- build
|   |-- bin
|   |   |-- entrypoint
|   |   `-- user_setup
|   |-- Dockerfile
|   `-- _output
|       `-- bin
|           `-- imoocpod-operator
|-- cmd
|   `-- manager
|       `-- main.go
|-- deploy
|   |-- crds
|   |   |-- k8s.imooc.com_imoocpods_crd.yaml
|   |   `-- k8s.imooc.com_v1alpha1_imoocpod_cr.yaml
|   |-- operator.yaml
|   |-- role_binding.yaml
|   |-- role.yaml
|   `-- service_account.yaml
|-- go.mod
|-- go.sum
|-- pkg
|   |-- apis
|   |   |-- addtoscheme_k8s_v1alpha1.go
|   |   |-- apis.go
|   |   `-- k8s
|   |       |-- group.go
|   |       `-- v1alpha1
|   |           |-- doc.go
|   |           |-- imoocpod_types.go
|   |           |-- register.go
|   |           `-- zz_generated.deepcopy.go
|   `-- controller
|       |-- add_imoocpod.go
|       |-- controller.go
|       `-- imoocpod
|           `-- imoocpod_controller.go
|-- tools.go
`-- version
    `-- version.go

15 directories, 25 files

部署operator

kubectl apply -f deploy/service_account.yaml

kubectl apply -f deploy/role.yaml

kubectl apply -f deploy/role_binding.yaml

kubectl apply -f deploy/operator.yaml

（這里需要修改一個operator.yaml里面的鏡像我填的是we8015/imooc-operator，大家可以自己找還有很多。）

 

部署CRD 部署CR

kubectl apply -f deploy/crds/k8s.imooc.com_imoocpods_crd.yaml

(需要先部署crd再部署operator 不然pod起不來)

kubectl apply -f deploy/crds/k8s.imooc.com_v1alpha1_imoocpod_cr.yaml

更新imoocpod_type.go文件

 

然后更新k8s.imooc.com_v1alpha1_imoocpod_cr.yaml

每次修改都需要更新一下相關的資源 如下

operator-sdk generate k8s

operator-sdk generate crds

然后就可以用新的yaml文件部署到k8s中了，這個時候會發現，crd是部署成功了，但是沒有生效，那是因為咱們還沒有編寫controller。

四、編寫controller

只需要編寫imoocpod_controller.go文件

package imoocpod

import (
	"context"
	"k8s.io/apimachinery/pkg/labels"
	"reflect"

	k8sv1alpha1 "github.com/imooc-com/imoocpod-operator/pkg/apis/k8s/v1alpha1"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	logf "sigs.k8s.io/controller-runtime/pkg/log"
	"sigs.k8s.io/controller-runtime/pkg/manager"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"
)

var log = logf.Log.WithName("controller_imoocpod")

/**
* USER ACTION REQUIRED: This is a scaffold file intended for the user to modify with their own Controller
* business logic.  Delete these comments after modifying this file.*
 */

// Add creates a new ImoocPod Controller and adds it to the Manager. The Manager will set fields on the Controller
// and Start it when the Manager is Started.
func Add(mgr manager.Manager) error {
	return add(mgr, newReconciler(mgr))
}

// newReconciler returns a new reconcile.Reconciler
func newReconciler(mgr manager.Manager) reconcile.Reconciler {
	return &ReconcileImoocPod{client: mgr.GetClient(), scheme: mgr.GetScheme()}
}

// add adds a new Controller to mgr with r as the reconcile.Reconciler
func add(mgr manager.Manager, r reconcile.Reconciler) error {
	// Create a new controller
	c, err := controller.New("imoocpod-controller", mgr, controller.Options{Reconciler: r})
	if err != nil {
		return err
	}

	// Watch for changes to primary resource ImoocPod
	err = c.Watch(&source.Kind{Type: &k8sv1alpha1.ImoocPod{}}, &handler.EnqueueRequestForObject{})
	if err != nil {
		return err
	}

	// TODO(user): Modify this to be the types you create that are owned by the primary resource
	// Watch for changes to secondary resource Pods and requeue the owner ImoocPod
	err = c.Watch(&source.Kind{Type: &corev1.Pod{}}, &handler.EnqueueRequestForOwner{
		IsController: true,
		OwnerType:    &k8sv1alpha1.ImoocPod{},
	})
	if err != nil {
		return err
	}

	return nil
}

// blank assignment to verify that ReconcileImoocPod implements reconcile.Reconciler
var _ reconcile.Reconciler = &ReconcileImoocPod{}

// ReconcileImoocPod reconciles a ImoocPod object
type ReconcileImoocPod struct {
	// This client, initialized using mgr.Client() above, is a split client
	// that reads objects from the cache and writes to the apiserver
	client client.Client
	scheme *runtime.Scheme
}

// Reconcile reads that state of the cluster for a ImoocPod object and makes changes based on the state read
// and what is in the ImoocPod.Spec
// TODO(user): Modify this Reconcile function to implement your Controller logic.  This example creates
// a Pod as an example
// Note:
// The Controller will requeue the Request to be processed again if the returned error is non-nil or
// Result.Requeue is true, otherwise upon completion it will remove the work from the queue.
func (r *ReconcileImoocPod) Reconcile(request reconcile.Request) (reconcile.Result, error) {
	reqLogger := log.WithValues("Request.Namespace", request.Namespace, "Request.Name", request.Name)
	reqLogger.Info("Reconciling ImoocPod")

	// Fetch the ImoocPod instance
	instance := &k8sv1alpha1.ImoocPod{}
	err := r.client.Get(context.TODO(), request.NamespacedName, instance)
	if err != nil {
		if errors.IsNotFound(err) {
			// Request object not found, could have been deleted after reconcile request.
			// Owned objects are automatically garbage collected. For additional cleanup logic use finalizers.
			// Return and don't requeue
			return reconcile.Result{}, nil
		}
		// Error reading the object - requeue the request.
		return reconcile.Result{}, err
	}

	lbls := labels.Set{
		"app": instance.Name,
	}
	existingPods := &corev1.PodList{}
	//1:獲取name對應的所以的pod列表
	err = r.client.List(context.TODO(), existingPods, &client.ListOptions{
		Namespace:     request.Namespace,
		LabelSelector: labels.SelectorFromSet(lbls),
	})
	if err != nil {
		reqLogger.Error(err, "取已經存在的pod失敗")
		return reconcile.Result{}, err
	}

	//2:取到pod列表中的pod name
	var existingPodNames []string
	for _, pod := range existingPods.Items {
		if pod.GetObjectMeta().GetDeletionTimestamp() != nil {
			continue
		}

		if pod.Status.Phase == corev1.PodPending || pod.Status.Phase == corev1.PodRunning {
			existingPodNames = append(existingPodNames, pod.GetObjectMeta().GetName())
		}

	}

	//3:update pod.status !=運行中的status
	//比較 DeepEqual
	status := k8sv1alpha1.ImoocPodStatus{ //期望的status
		PodNames: existingPodNames,
		Replicas: len(existingPodNames),
	}
	if !reflect.DeepEqual(instance.Status, status) {
		instance.Status = status //把期望狀態給運行態
		err = r.client.Status().Update(context.TODO(), instance)
		if err != nil {
			reqLogger.Error(err, "更新pod的狀態失敗")
			return reconcile.Result{}, err
		}
	}

	//4:len(pod)>運行中的len(pod.replace)，期望值小，需要scale down
	if len(existingPodNames) > instance.Spec.Replicas {
		//delete
		reqLogger.Info("正在刪除Pod,當前的podnames和期望的Replicas:", existingPodNames, instance.Spec.Replicas)
		pod := existingPods.Items[0]
		err := r.client.Delete(context.TODO(), &pod)
		if err != nil {
			reqLogger.Error(err, "刪除pod失敗")
			return reconcile.Result{}, err
		}
	}

	//5:len(pod)<運行中的len(pod.replace)，期望值大，需要scale up create
	if len(existingPodNames) < instance.Spec.Replicas {
		//create
		reqLogger.Info("正在創建Pod,當前的podnames和期望的Replicas:", existingPodNames, instance.Spec.Replicas)
		// Define a new Pod object
		pod := newPodForCR(instance)

		// Set ImoocPod instance as the owner and controller
		if err := controllerutil.SetControllerReference(instance, pod, r.scheme); err != nil {
			return reconcile.Result{}, err
		}

		err = r.client.Create(context.TODO(), pod)
		if err != nil {
			reqLogger.Error(err, "創建pod失敗")
			return reconcile.Result{}, err
		}
	}

	 Define a new Pod object
	//pod := newPodForCR(instance)
	//
	 Set ImoocPod instance as the owner and controller
	//if err := controllerutil.SetControllerReference(instance, pod, r.scheme); err != nil {
	//	return reconcile.Result{}, err
	//}
	//
	 Check if this Pod already exists
	//found := &corev1.Pod{}
	//err = r.client.Get(context.TODO(), types.NamespacedName{Name: pod.Name, Namespace: pod.Namespace}, found)
	//if err != nil && errors.IsNotFound(err) {
	//	reqLogger.Info("Creating a new Pod", "Pod.Namespace", pod.Namespace, "Pod.Name", pod.Name)
	//	err = r.client.Create(context.TODO(), pod)
	//	if err != nil {
	//		return reconcile.Result{}, err
	//	}
	//
	//	// Pod created successfully - don't requeue
	//	return reconcile.Result{}, nil
	//} else if err != nil {
	//	return reconcile.Result{}, err
	//}
	//
	 Pod already exists - don't requeue
	//reqLogger.Info("Skip reconcile: Pod already exists", "Pod.Namespace", found.Namespace, "Pod.Name", found.Name)
	//return reconcile.Result{}, nil
	return reconcile.Result{Requeue: true}, nil
}

// newPodForCR returns a busybox pod with the same name/namespace as the cr
func newPodForCR(cr *k8sv1alpha1.ImoocPod) *corev1.Pod {
	labels := map[string]string{
		"app": cr.Name,
	}
	return &corev1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			GenerateName:      cr.Name + "-pod",
			Namespace: cr.Namespace,
			Labels:    labels,
		},
		Spec: corev1.PodSpec{
			Containers: []corev1.Container{
				{
					Name:    "busybox",
					Image:   "busybox",
					Command: []string{"sleep", "3600"},
				},
			},
		},
	}
}

同意的需要更新一下相關的配置

operator-sdk generate k8s

operator-sdk generate crds

然后是推送鏡像，operator build we8105/imooc-operator (we8105這里是鏡像的名稱)

推送到遠端  docker push we8105/imooc-operator

然后更新一下operator中的鏡像就行。

最后就是測試了，可以查看日志和get pod查看pod數量發現生效了。

 

完。