最大化CustomResourceDefinition可以拥有的CustomResources数量 | kubebuilder和operator-sdk

huangapple
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英文:

Maximize the number of CustomResources that a CustomResourceDefinition can have | kubebuilder & operator-sdk

问题

我正在开发一个 Kubernetes Operator，它代表了一个非常简单的 API 和一个控制器。
我想要最大化属于操作员定义的特定 CustomResourceDefinition 的 CustomResources 的数量。（特别是，如果已经定义了一个 CR，操作员应该抛出一个错误消息并跳过对其进行调和。）
如果我生成了 API，会默认生成一个 KindList 结构体，并且如果我理解正确的话，它应该跟踪已为我的 CRD 定义的 CR。它也会默认添加到 scheme 中。请参考 kubebuilder 文档中的示例：

  1. //+kubebuilder:object:root=true
  2. //+kubebuilder:subresource:status
  4. // CronJob is the Schema for the cronjobs API
  5. type CronJob struct {
  6.     metav1.TypeMeta   `json:",inline"`
  7.     metav1.ObjectMeta `json:"metadata,omitempty"`
  9.     Spec   CronJobSpec   `json:"spec,omitempty"`
  10.     Status CronJobStatus `json:"status,omitempty"`
  11. }
  13. //+kubebuilder:object:root=true
  15. // CronJobList contains a list of CronJob
  16. type CronJobList struct {
  17.     metav1.TypeMeta `json:",inline"`
  18.     metav1.ListMeta `json:"metadata,omitempty"`
  19.     Items           []CronJob `json:"items"`
  20. }
  22. func init() {
  23.     SchemeBuilder.Register(&CronJob{}, &CronJobList{})
  24. }

不幸的是，我找不到如何从控制器中访问这个 List。我尝试过这样，但是 r.Get 无法接受 cacheList：

  1. cronjob/cronjob_controller.go
  3. package controllers
  5. import (
  6. 	"context"
  8. 	"k8s.io/apimachinery/pkg/runtime"
  9. 	ctrl "sigs.k8s.io/controller-runtime"
  10. 	"sigs.k8s.io/controller-runtime/pkg/client"
  11. 	"sigs.k8s.io/controller-runtime/pkg/log"
  13. 	cronjobv1alpha1 "github.com/example/cronjob-operator/api/v1alpha1"
  14. )
  16. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  17. 	_ = log.FromContext(ctx)
  19. 	// TODO(user): your logic here
  21. 	cronjob := cronjobv1alpha1.Memcached{}
  22. 	if err := r.Get(ctx, req.NamespacedName, &cronjob); err != nil {
  23. 		return ctrl.Result{}, err
  24. 	}
  26. 	cronjobList := cachev1alpha1.MemcachedList{}
  27. 	if err := r.Get(ctx, req.NamespacedName, &cronjobList); err != nil {
  28. 		return ctrl.Result{}, err
  29. 	}
  31. 	return ctrl.Result{}, nil
  32. }

如果我获取了这个列表，我可以验证它的长度，并根据需要执行或跳过调和。

这种方法是否正确？是否有更好的方法来实现我的目标？我应该创建一个 webhook 吗？

英文:

I'm developing a kubernetes operator that represents a very simple api and a controller.
I would like to maximize the number of the CustomResources those could belonging to the specific CustomResourceDefinition that the operator defines. (As specially I would like to allow just one CR, if it is already defined, the operator should throw an error message and skip reconciling it.)
If I generate the api, there is a KindList struct default generated, and if I understand correctly, it should keep track of the CRs already defined for my CRD. It is also added to the scheme by default. See the example from kubebuilder documentation:

  1. //+kubebuilder:object:root=true
  2. //+kubebuilder:subresource:status
  4. // CronJob is the Schema for the cronjobs API
  5. type CronJob struct {
  6.     metav1.TypeMeta   `json:",inline"`
  7.     metav1.ObjectMeta `json:"metadata,omitempty"`
  9.     Spec   CronJobSpec   `json:"spec,omitempty"`
  10.     Status CronJobStatus `json:"status,omitempty"`
  11. }
  13. //+kubebuilder:object:root=true
  15. // CronJobList contains a list of CronJob
  16. type CronJobList struct {
  17.     metav1.TypeMeta `json:",inline"`
  18.     metav1.ListMeta `json:"metadata,omitempty"`
  19.     Items           []CronJob `json:"items"`
  20. }
  22. func init() {
  23.     SchemeBuilder.Register(&CronJob{}, &CronJobList{})
  24. }

Unfortunately, I can not find out how to access this List from the controller. I have tried like this, but r.Get can not accept cacheList:

  1. cronjob/cronjob_controller.go
  3. package controllers
  5. import (
  6. 	"context"
  8. 	"k8s.io/apimachinery/pkg/runtime"
  9. 	ctrl "sigs.k8s.io/controller-runtime"
  10. 	"sigs.k8s.io/controller-runtime/pkg/client"
  11. 	"sigs.k8s.io/controller-runtime/pkg/log"
  13. 	cronjobv1alpha1 "github.com/example/cronjob-operator/api/v1alpha1"
  14. )
  16. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  17. 	_ = log.FromContext(ctx)
  19. 	// TODO(user): your logic here
  21. 	cronjob := cronjobv1alpha1.Memcached{}
  22. 	if err := r.Get(ctx, req.NamespacedName, &cronjob); err != nil {
  23. 		return ctrl.Result{}, err
  24. 	}
  26. 	cronjobList := cachev1alpha1.MemcachedList{}
  27. 	if err := r.Get(ctx, req.NamespacedName, &cronjobList); err != nil {
  28. 		return ctrl.Result{}, err
  29. 	}
  31. 	return ctrl.Result{}, nil
  32. }

If I get the list, I could validate the length of it, and do or skip the reconcile.

Is it even a correct approach? Is there a better way to achieve my goal? Should I create a webhook instead?

答案1

得分: 2

假设您正在使用默认的sigs.k8s.io/controller-runtime/pkg/client的client.Client，您可以访问List()函数。

在您的情况下，使用r.List(...)。

用法如下：

情况1：按标签列出

  1. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  2.     cronjobList := cronjobv1alpha1.CronJobList{}
  3. 	err = r.List(ctx, &cronjobList, client.MatchingLabels{"foo": "bar"})
  4. 	if err != nil {
  5. 		return ctrl.Result{}, err
  6. 	}
  7. }

情况2：列出命名空间中的所有对象

  1. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  2.     cronjobList := cronjobv1alpha1.CronJobList{}
  3. 	err = r.List(ctx, &cronjobList, client.InNamespace("default"))
  4. 	if err != nil {
  5. 		return ctrl.Result{}, err
  6. 	}
  7. }

情况3：按字段（例如metadata.name）列出

  1. // 在您的Reconciler Setup函数中创建一个索引
  2. func SetupWithManager(mgr ctrl.Manager) error {
  3. 	r := &CronJobReconciler{
  4. 		Client:   mgr.GetClient(),
  5. 	}
  6. 	mgr.GetFieldIndexer().IndexField(context.TODO(), &cronjobv1alpha1.CronJob{}, "metadata.name", NameIndexer)
  8.     return ctrl.NewControllerManagedBy(mgr).
  9.         For(&cronjobv1alpha1.CronJob{}).
  10.         Complete(r)
  11. }    
  13. func NameIndexer(o client.Object) []string {
  14. 	m := o.(*cronjobv1alpha1.CronJob)
  15. 	return []string{m.ObjectMeta.Name}
  16. }
  18. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  19.     cronjobList := cronjobv1alpha1.CronJobList{}
  20. 	err = r.List(ctx, &cronjobList, client.MatchingFields{"metadata.name": "test"})
  21. 	if err != nil {
  22. 		return ctrl.Result{}, err
  23. 	}
  24. }
英文:

Assuming you are using the default sigs.k8s.io/controller-runtime/pkg/client's client.Client, you get access to the List() function.

In your case r.List(...).

Usage:

case 1: list by label

  1. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  2.     cronjobList := cronjobv1alpha1.CronJobList{}
  3. 	err = r.List(ctx, &cronjobList, client.MatchingLabels{"foo": "bar"})
  4. 	if err != nil {
  5. 		return ctrl.Result{}, err
  6. 	}
  7. }

case 2: list all in namespace

  1. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  2.     cronjobList := cronjobv1alpha1.CronJobList{}
  3. 	err = r.List(ctx, &cronjobList, client.InNamespace("default"))
  4. 	if err != nil {
  5. 		return ctrl.Result{}, err
  6. 	}
  7. }

case 3: list by field i.e. metadata.name

  1. // in your Reconciler Setup function create an index
  2. func SetupWithManager(mgr ctrl.Manager) error {
  3. 	r := &CronJobReconciler{
  4. 		Client:   mgr.GetClient(),
  5. 	}
  6. 	mgr.GetFieldIndexer().IndexField(context.TODO(), &cronjobv1alpha1.CronJob{}, "metadata.name", NameIndexer)
  8.     return ctrl.NewControllerManagedBy(mgr).
  9.         For(&cronjobv1alpha1.CronJob{}).
  10.         Complete(r)
  11. }    
  13. func NameIndexer(o client.Object) []string {
  14. 	m := o.(*cronjobv1alpha1.CronJob)
  15. 	return []string{m.ObjectMeta.Name}
  16. }
  18. func (r *CronJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  19.     cronjobList := cronjobv1alpha1.CronJobList{}
  20. 	err = r.List(ctx, &cronjobList, client.MatchingFields{"metadata.name": "test"})
  21. 	if err != nil {
  22. 		return ctrl.Result{}, err
  23. 	}
  24. }

huangapple
  • 本文由 发表于 2022年10月21日 03:11:18
  • 转载请务必保留本文链接：https://go.coder-hub.com/74145169.html
  • go
  • kubebuilder
  • kubernetes
  • operator-sdk
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