sigs.k8s.io/cluster-api@v1.7.1/controllers/external/tracker.go (about)

     1  /*
     2  Copyright 2020 The Kubernetes Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package external
    18  
    19  import (
    20  	"fmt"
    21  	"sync"
    22  
    23  	"github.com/go-logr/logr"
    24  	"github.com/pkg/errors"
    25  	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
    26  	"k8s.io/apimachinery/pkg/runtime"
    27  	"sigs.k8s.io/controller-runtime/pkg/cache"
    28  	"sigs.k8s.io/controller-runtime/pkg/controller"
    29  	"sigs.k8s.io/controller-runtime/pkg/handler"
    30  	"sigs.k8s.io/controller-runtime/pkg/predicate"
    31  	"sigs.k8s.io/controller-runtime/pkg/source"
    32  
    33  	"sigs.k8s.io/cluster-api/util/predicates"
    34  )
    35  
    36  // ObjectTracker is a helper struct to deal when watching external unstructured objects.
    37  type ObjectTracker struct {
    38  	m sync.Map
    39  
    40  	Controller controller.Controller
    41  	Cache      cache.Cache
    42  }
    43  
    44  // Watch uses the controller to issue a Watch only if the object hasn't been seen before.
    45  func (o *ObjectTracker) Watch(log logr.Logger, obj runtime.Object, handler handler.EventHandler, p ...predicate.Predicate) error {
    46  	// Consider this a no-op if the controller isn't present.
    47  	if o.Controller == nil {
    48  		return nil
    49  	}
    50  
    51  	gvk := obj.GetObjectKind().GroupVersionKind()
    52  	key := gvk.GroupKind().String()
    53  	if _, loaded := o.m.LoadOrStore(key, struct{}{}); loaded {
    54  		return nil
    55  	}
    56  
    57  	u := &unstructured.Unstructured{}
    58  	u.SetGroupVersionKind(gvk)
    59  
    60  	log.Info(fmt.Sprintf("Adding watch on external object %q", gvk.String()))
    61  	err := o.Controller.Watch(
    62  		source.Kind(o.Cache, u),
    63  		handler,
    64  		append(p, predicates.ResourceNotPaused(log))...,
    65  	)
    66  	if err != nil {
    67  		o.m.Delete(key)
    68  		return errors.Wrapf(err, "failed to add watch on external object %q", gvk.String())
    69  	}
    70  	return nil
    71  }