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5.4.2.4. 实现控制器

在创建新 API 和控制器后,您可以实现控制器逻辑。

流程

  • 在本例中,将生成的控制器文件 controllers/memcached_controller.go 替换为以下示例实现:

    例 5.28. memcached_controller.go示例

    /*
    Copyright 2020.
    
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at
    
        http://www.apache.org/licenses/LICENSE-2.0
    
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
    */
    
    package controllers
    
    import (
    	appsv1 "k8s.io/api/apps/v1"
    	corev1 "k8s.io/api/core/v1"
    	"k8s.io/apimachinery/pkg/api/errors"
    	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
    	"k8s.io/apimachinery/pkg/types"
    	"reflect"
    
    	"context"
    
    	"github.com/go-logr/logr"
    	"k8s.io/apimachinery/pkg/runtime"
    	ctrl "sigs.k8s.io/controller-runtime"
    	"sigs.k8s.io/controller-runtime/pkg/client"
    
    	cachev1alpha1 "github.com/example/memcached-operator/api/v1alpha1"
    )
    
    // MemcachedReconciler reconciles a Memcached object
    type MemcachedReconciler struct {
    	client.Client
    	Log    logr.Logger
    	Scheme *runtime.Scheme
    }
    
    // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds,verbs=get;list;watch;create;update;patch;delete
    // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds/status,verbs=get;update;patch
    // +kubebuilder:rbac:groups=cache.example.com,resources=memcacheds/finalizers,verbs=update
    // +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;patch;delete
    // +kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;
    
    // Reconcile is part of the main kubernetes reconciliation loop which aims to
    // move the current state of the cluster closer to the desired state.
    // TODO(user): Modify the Reconcile function to compare the state specified by
    // the Memcached object against the actual cluster state, and then
    // perform operations to make the cluster state reflect the state specified by
    // the user.
    //
    // For more details, check Reconcile and its Result here:
    // - https://pkg.go.dev/sigs.k8s.io/controller-runtime@v0.7.0/pkg/reconcile
    func (r *MemcachedReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
    	log := r.Log.WithValues("memcached", req.NamespacedName)
    
    	// Fetch the Memcached instance
    	memcached := &cachev1alpha1.Memcached{}
    	err := r.Get(ctx, req.NamespacedName, memcached)
    	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
    			log.Info("Memcached resource not found. Ignoring since object must be deleted")
    			return ctrl.Result{}, nil
    		}
    		// Error reading the object - requeue the request.
    		log.Error(err, "Failed to get Memcached")
    		return ctrl.Result{}, err
    	}
    
    	// Check if the deployment already exists, if not create a new one
    	found := &appsv1.Deployment{}
    	err = r.Get(ctx, types.NamespacedName{Name: memcached.Name, Namespace: memcached.Namespace}, found)
    	if err != nil && errors.IsNotFound(err) {
    		// Define a new deployment
    		dep := r.deploymentForMemcached(memcached)
    		log.Info("Creating a new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
    		err = r.Create(ctx, dep)
    		if err != nil {
    			log.Error(err, "Failed to create new Deployment", "Deployment.Namespace", dep.Namespace, "Deployment.Name", dep.Name)
    			return ctrl.Result{}, err
    		}
    		// Deployment created successfully - return and requeue
    		return ctrl.Result{Requeue: true}, nil
    	} else if err != nil {
    		log.Error(err, "Failed to get Deployment")
    		return ctrl.Result{}, err
    	}
    
    	// Ensure the deployment size is the same as the spec
    	size := memcached.Spec.Size
    	if *found.Spec.Replicas != size {
    		found.Spec.Replicas = &size
    		err = r.Update(ctx, found)
    		if err != nil {
    			log.Error(err, "Failed to update Deployment", "Deployment.Namespace", found.Namespace, "Deployment.Name", found.Name)
    			return ctrl.Result{}, err
    		}
    		// Spec updated - return and requeue
    		return ctrl.Result{Requeue: true}, nil
    	}
    
    	// Update the Memcached status with the pod names
    	// List the pods for this memcached's deployment
    	podList := &corev1.PodList{}
    	listOpts := []client.ListOption{
    		client.InNamespace(memcached.Namespace),
    		client.MatchingLabels(labelsForMemcached(memcached.Name)),
    	}
    	if err = r.List(ctx, podList, listOpts...); err != nil {
    		log.Error(err, "Failed to list pods", "Memcached.Namespace", memcached.Namespace, "Memcached.Name", memcached.Name)
    		return ctrl.Result{}, err
    	}
    	podNames := getPodNames(podList.Items)
    
    	// Update status.Nodes if needed
    	if !reflect.DeepEqual(podNames, memcached.Status.Nodes) {
    		memcached.Status.Nodes = podNames
    		err := r.Status().Update(ctx, memcached)
    		if err != nil {
    			log.Error(err, "Failed to update Memcached status")
    			return ctrl.Result{}, err
    		}
    	}
    
    	return ctrl.Result{}, nil
    }
    
    // deploymentForMemcached returns a memcached Deployment object
    func (r *MemcachedReconciler) deploymentForMemcached(m *cachev1alpha1.Memcached) *appsv1.Deployment {
    	ls := labelsForMemcached(m.Name)
    	replicas := m.Spec.Size
    
    	dep := &appsv1.Deployment{
    		ObjectMeta: metav1.ObjectMeta{
    			Name:      m.Name,
    			Namespace: m.Namespace,
    		},
    		Spec: appsv1.DeploymentSpec{
    			Replicas: &replicas,
    			Selector: &metav1.LabelSelector{
    				MatchLabels: ls,
    			},
    			Template: corev1.PodTemplateSpec{
    				ObjectMeta: metav1.ObjectMeta{
    					Labels: ls,
    				},
    				Spec: corev1.PodSpec{
    					Containers: []corev1.Container{{
    						Image:   "memcached:1.4.36-alpine",
    						Name:    "memcached",
    						Command: []string{"memcached", "-m=64", "-o", "modern", "-v"},
    						Ports: []corev1.ContainerPort{{
    							ContainerPort: 11211,
    							Name:          "memcached",
    						}},
    					}},
    				},
    			},
    		},
    	}
    	// Set Memcached instance as the owner and controller
    	ctrl.SetControllerReference(m, dep, r.Scheme)
    	return dep
    }
    
    // labelsForMemcached returns the labels for selecting the resources
    // belonging to the given memcached CR name.
    func labelsForMemcached(name string) map[string]string {
    	return map[string]string{"app": "memcached", "memcached_cr": name}
    }
    
    // getPodNames returns the pod names of the array of pods passed in
    func getPodNames(pods []corev1.Pod) []string {
    	var podNames []string
    	for _, pod := range pods {
    		podNames = append(podNames, pod.Name)
    	}
    	return podNames
    }
    
    // SetupWithManager sets up the controller with the Manager.
    func (r *MemcachedReconciler) SetupWithManager(mgr ctrl.Manager) error {
    	return ctrl.NewControllerManagedBy(mgr).
    		For(&cachev1alpha1.Memcached{}).
    		Owns(&appsv1.Deployment{}).
    		Complete(r)
    }

    示例控制器为每个 Memcached 自定义资源(CR)运行以下协调逻辑:

    • 如果尚无 Memcached 部署,创建一个。
    • 确保部署大小与 Memcached CR spec 指定的大小相同。
    • 使用 memcached Pod 的名称更新 Memcached CR 状态。

下面的小节解释了示例中的控制器如何监视资源以及如何触发协调循环。您可以跳过这些小节以,直接进入运行 Operator

5.4.2.4.1. 控制器监视的资源

controllers/memcached_controller.go 中的 SetupWithManager() 功能指定如何构建控制器来监视 CR 和其他控制器拥有和管理的资源。

import (
	...
	appsv1 "k8s.io/api/apps/v1"
	...
)

func (r *MemcachedReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).
		For(&cachev1.Memcached{}).
		Owns(&appsv1.Deployment{}).
		Complete(r)
}

NewControllerManagedBy() 提供了一个控制器构建器,它允许各种控制器配置。

for(&cachev1.Memcached{})Memcached 类型指定为要监视的主要资源。对于 Memcached 类型的每个 Add、Update 或 Delete 事件,协调循环都会为该 Memcached 对象发送一个协调 Request 参数,其中包括命名空间和名称键。

owns(&appsv1.Deployment{})Deployment 类型指定为要监视的辅助资源。对于 Deployment 类型的每个 Add、Update 或 Delete 事件,事件处理程序会将每个事件映射到部署所有者的协调请求。在本例中,所有者是创建部署的 Memcached 对象。