kubebuilder operator的运行逻辑

mgr, err := ctrl.NewManager(ctrl.GetConfigOrDie(), ctrl.Options{
    Scheme:                 scheme,
    MetricsBindAddress:     metricsAddr,
    Port:                   9443,
    HealthProbeBindAddress: probeAddr,
    LeaderElection:         enableLeaderElection,
    LeaderElectionID:       "3b9f5c61.com.bolingcavalry",
  })

func New(name string, mgr manager.Manager, options Options) (Controller, error) {
  c, err := NewUnmanaged(name, mgr, options)
  if err != nil {
    return nil, err
  }
  // Add the controller as a Manager components
  return c, mgr.Add(c) // 将controller添加到manager中
}

func (r *GuestbookReconciler) SetupWithManager(mgr ctrl.Manager) error {
  return ctrl.NewControllerManagedBy(mgr).
    For(&webappv1.Guestbook{}).
    Complete(r)
}

mgr.Start(ctrl.SetupSignalHandler())

// Request contains the information necessary to reconcile a Kubernetes object.  This includes the
// information to uniquely identify the object - its Name and Namespace.  It does NOT contain information about
// any specific Event or the object contents itself.
type Request struct {
  // NamespacedName is the name and namespace of the object to reconcile.
  types.NamespacedName
}

// NamespacedName comprises a resource name, with a mandatory namespace,
// rendered as "<namespace>/<name>".  Being a type captures intent and
// helps make sure that UIDs, namespaced names and non-namespaced names
// do not get conflated in code.  For most use cases, namespace and name
// will already have been format validated at the API entry point, so we
// don't do that here.  Where that's not the case (e.g. in testing),
// consider using NamespacedNameOrDie() in testing.go in this package.
type NamespacedName struct {
  Namespace string
  Name      string
}

/*
Reconciler implements a Kubernetes API for a specific Resource by Creating, Updating or Deleting Kubernetes
objects, or by making changes to systems external to the cluster (e.g. cloudproviders, github, etc).
 
reconcile implementations compare the state specified in an object by a user against the actual cluster state,
and then perform operations to make the actual cluster state reflect the state specified by the user.
 
Typically, reconcile is triggered by a Controller in response to cluster Events (e.g. Creating, Updating,
Deleting Kubernetes objects) or external Events (GitHub Webhooks, polling external sources, etc).
 
Example reconcile Logic:
 
  * Read an object and all the Pods it owns.
  * Observe that the object spec specifies 5 replicas but actual cluster contains only 1 Pod replica.
  * Create 4 Pods and set their OwnerReferences to the object.
 
reconcile may be implemented as either a type:
 
  type reconcile struct {}
 
  func (reconcile) reconcile(controller.Request) (controller.Result, error) {
    // Implement business logic of reading and writing objects here
    return controller.Result{}, nil
  }
 
Or as a function:
 
  controller.Func(func(o controller.Request) (controller.Result, error) {
    // Implement business logic of reading and writing objects here
    return controller.Result{}, nil
  })
 
Reconciliation is level-based, meaning action isn't driven off changes in individual Events, but instead is
driven by actual cluster state read from the apiserver or a local cache.
For example if responding to a Pod Delete Event, the Request won't contain that a Pod was deleted,
instead the reconcile function observes this when reading the cluster state and seeing the Pod as missing.
*/
type Reconciler interface {
  // Reconcile performs a full reconciliation for the object referred to by the Request.
  // The Controller will requeue the Request to be processed again if an error is non-nil or
  // Result.Requeue is true, otherwise upon completion it will remove the work from the queue.
  Reconcile(context.Context, Request) (Result, error)
}

case err != nil:
    if errors.Is(err, reconcile.TerminalError(nil)) {
      ctrlmetrics.TerminalReconcileErrors.WithLabelValues(c.Name).Inc()
    } else {
      c.Queue.AddRateLimited(req)
    }
    ...
  case result.RequeueAfter > 0: //超时方式重新调用
    log.V(5).Info(fmt.Sprintf("Reconcile done, requeueing after %s", result.RequeueAfter))
    // The result.RequeueAfter request will be lost, if it is returned
    // along with a non-nil error. But this is intended as
    // We need to drive to stable reconcile loops before queuing due
    // to result.RequestAfter
    c.Queue.Forget(obj)
    c.Queue.AddAfter(req, result.RequeueAfter)
    ctrlmetrics.ReconcileTotal.WithLabelValues(c.Name, labelRequeueAfter).Inc()
  case result.Requeue: //非周期性方式调用
    log.V(5).Info("Reconcile done, requeueing")
    c.Queue.AddRateLimited(req)
    ctrlmetrics.ReconcileTotal.WithLabelValues(c.Name, labelRequeue).Inc()

func (r *GuestbookReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
  _ = log.FromContext(ctx)
  // TODO(user): your logic here
  return ctrl.Result{}, nil
}

// Complete builds the Application Controller.
func (blder *Builder) Complete(r reconcile.Reconciler) error {
  _, err := blder.Build(r)
  return err
}

// Create controller with dependencies set
  return &controller.Controller{
    Do: options.Reconciler,
    MakeQueue: func() workqueue.RateLimitingInterface {
      return workqueue.NewRateLimitingQueueWithConfig(options.RateLimiter, workqueue.RateLimitingQueueConfig{
        Name: name,
      })
    },
    MaxConcurrentReconciles: options.MaxConcurrentReconciles,
    CacheSyncTimeout:        options.CacheSyncTimeout,
    Name:                    name,
    LogConstructor:          options.LogConstructor,
    RecoverPanic:            options.RecoverPanic,
    LeaderElected:           options.NeedLeaderElection,
  }, nil

func (c *Controller) Start(ctx context.Context) error {
  ...
  c.Queue = c.MakeQueue() //通过MakeQueue初始化一个workqueue
  ...
  wg := &sync.WaitGroup{}
  err := func() error {
    ...
    for _, watch := range c.startWatches { //启动watch object
      ...
      if err := watch.src.Start(ctx, watch.handler, c.Queue, watch.predicates...); err != nil {
        return err
      }
    }
    ...
    wg.Add(c.MaxConcurrentReconciles)
    for i := 0; i < c.MaxConcurrentReconciles; i++ { //并发处理时间
      go func() {
        defer wg.Done()
        for c.processNextWorkItem(ctx) {
        }
      }()
    }
    ...
  }()
  ...
}

func (c *Controller) processNextWorkItem(ctx context.Context) bool {
  obj, shutdown := c.Queue.Get() //获取workqueue中的对象
  if shutdown {
    // Stop working
    return false
  }
  defer c.Queue.Done(obj)
  ctrlmetrics.ActiveWorkers.WithLabelValues(c.Name).Add(1)
  defer ctrlmetrics.ActiveWorkers.WithLabelValues(c.Name).Add(-1)
  c.reconcileHandler(ctx, obj)
  return true
}

func (blder *Builder) Build(r reconcile.Reconciler) (controller.Controller, error) {
  ...
  // Set the ControllerManagedBy
  if err := blder.doController(r); err != nil {//初始化controller
    return nil, err
  }
  // Set the Watch
  if err := blder.doWatch(); err != nil {
    return nil, err
  }
  return blder.ctrl, nil
}

func (blder *Builder) doWatch() error {
  // Reconcile type
if blder.forInput.object != nil { // watch For()方式引入的对象
    obj, err := blder.project(blder.forInput.object, blder.forInput.objectProjection)//格式化资源类型
    if err != nil {
      return err
    }
    src := source.Kind(blder.mgr.GetCache(), obj) //初始化资源类型
    hdler := &handler.EnqueueRequestForObject{}   //初始化eventHandler
    allPredicates := append(blder.globalPredicates, blder.forInput.predicates...)
    if err := blder.ctrl.Watch(src, hdler, allPredicates...); err != nil { //启动对资源的监控
      return err
    }
  }
  ...
  for _, own := range blder.ownsInput { // watch Owns()方式引入的对象
    ...
    if err := blder.ctrl.Watch(src, hdler, allPredicates...); err != nil { //启动对资源的监控
      return err
    }
  ...
  }
  ...
  for _, w := range blder.watchesInput { // watch Watches()方式引入的对象
  ...
    if err := blder.ctrl.Watch(w.src, w.eventHandler, allPredicates...); err != nil { //启动对资源的监控
      return err
    }
  ...
  }
    ...
}

_ = ctrl.NewControllerManagedBy(mgr).
    For(&appsv1.ReplicaSet{}).       // ReplicaSet is the Application API
    Owns(&corev1.Pod{}).             // ReplicaSet owns Pods created by it.
    Complete(&ReplicaSetReconciler{Client: manager.GetClient()})

_ = ctrl.NewControllerManagedBy(mgr).
    Watches(
        &source.Kind{Type: &v1core.Node{}},
        handler.EnqueueRequestsFromMapFunc(myNodeFilterFunc),
        builder.WithPredicates(predicate.ResourceVersionChangedPredicate{}),
    ).
    Complete(r)

func (c *Controller) Watch(src source.Source, evthdler handler.EventHandler, prct ...predicate.Predicate) error {
   ...
return src.Start(c.ctx, evthdler, c.Queue, prct...)
}

func (ks *Kind) Start(ctx context.Context, handler handler.EventHandler, queue workqueue.RateLimitingInterface,
  prct ...predicate.Predicate) error {
  ...
  go func() {
    ...
    if err := wait.PollImmediateUntilWithContext(ctx, 10*time.Second, func(ctx context.Context) (bool, error) {
      // Lookup the Informer from the Cache and add an EventHandler which populates the Queue
      i, lastErr = ks.cache.GetInformer(ctx, ks.Type)
      ...
      return true, nil
    }); 
        ...
    _, err := i.AddEventHandler(NewEventHandler(ctx, queue, handler, prct).HandlerFuncs())  
    ...
  }()
  return nil
}

type ResourceEventHandler interface {
  OnAdd(obj interface{})
  OnUpdate(oldObj, newObj interface{})
  OnDelete(obj interface{})
}

func (e EventHandler) OnAdd(obj interface{}) {
  ...
  e.handler.Create(ctx, c, e.queue)
}

func (e *EnqueueRequestForObject) Create(ctx context.Context, evt event.CreateEvent, q workqueue.RateLimitingInterface) {
  ...
  q.Add(reconcile.Request{NamespacedName: types.NamespacedName{
    Name:      evt.Object.GetName(),
    Namespace: evt.Object.GetNamespace(),
  }})
}

package main
import (
  "context"
  corev1 "k8s.io/api/core/v1"
  "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
  "k8s.io/apimachinery/pkg/runtime/schema"
  "sigs.k8s.io/controller-runtime/pkg/client"
)
var c client.Client
func main() {
  // Using a typed object.
  pod := &corev1.Pod{}
  // c is a created client.
  _ = c.Get(context.Background(), client.ObjectKey{
    Namespace: "namespace",
    Name:      "name",
  }, pod)
  // Using a unstructured object.
  u := &unstructured.Unstructured{}
  u.SetGroupVersionKind(schema.GroupVersionKind{
    Group:   "apps",
    Kind:    "Deployment",
    Version: "v1",
  })
  _ = c.Get(context.Background(), client.ObjectKey{
    Namespace: "namespace",
    Name:      "name",
  }, u)
}