✨ Cluster Provider and cluster-aware controllers

Co-authored-by: Vince Prignano <vincepri@redhat.com>
Signed-off-by: Vince Prignano <vincepri@redhat.com>
Signed-off-by: Dr. Stefan Schimanski <stefan.schimanski@gmail.com>

examples/fleet-namespace/cache.go

@@ -0,0 +1,204 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+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 main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	toolscache "k8s.io/client-go/tools/cache"
+	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+const (
+	ClusterNameIndex = "cluster/name"
+	ClusterIndex     = "cluster"
+)
+
+var _ cache.Cache = &NamespacedCache{}
+
+type NamespacedCache struct {
+	clusterName string
+	cache.Cache
+}
+
+func (c *NamespacedCache) Get(ctx context.Context, key client.ObjectKey, obj client.Object, opts ...client.GetOption) error {
+	if key.Namespace != "default" {
+		return apierrors.NewNotFound(schema.GroupResource{}, key.Name)
+	}
+	key.Namespace = c.clusterName
+	if err := c.Cache.Get(ctx, key, obj, opts...); err != nil {
+		return err
+	}
+	obj.SetNamespace("default")
+	return nil
+}
+
+func (c *NamespacedCache) List(ctx context.Context, list client.ObjectList, opts ...client.ListOption) error {
+	var listOpts client.ListOptions
+	for _, o := range opts {
+		o.ApplyToList(&listOpts)
+	}
+
+	switch {
+	case listOpts.FieldSelector != nil:
+		reqs := listOpts.FieldSelector.Requirements()
+		flds := make(map[string]string, len(reqs))
+		for i := range reqs {
+			flds[fmt.Sprintf("cluster/%s", reqs[i].Field)] = fmt.Sprintf("%s/%s", c.clusterName, reqs[i].Value)
+		}
+		opts = append(opts, client.MatchingFields(flds))
+	case listOpts.Namespace != "":
+		opts = append(opts, client.MatchingFields(map[string]string{ClusterIndex: c.clusterName}))
+		if c.clusterName == "*" {
+			listOpts.Namespace = ""
+		} else if listOpts.Namespace == "default" {
+			listOpts.Namespace = c.clusterName
+		}
+	default:
+		opts = append(opts, client.MatchingFields(map[string]string{ClusterIndex: c.clusterName}))
+	}
+
+	if err := c.Cache.List(ctx, list, opts...); err != nil {
+		return err
+	}
+
+	return meta.EachListItem(list, func(obj runtime.Object) error {
+		obj.(client.Object).SetNamespace("default")
+		return nil
+	})
+}
+
+func (c *NamespacedCache) GetInformer(ctx context.Context, obj client.Object, opts ...cache.InformerGetOption) (cache.Informer, error) {
+	inf, err := c.Cache.GetInformer(ctx, obj, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &ScopedInformer{clusterName: c.clusterName, Informer: inf}, nil
+}
+
+func (c *NamespacedCache) GetInformerForKind(ctx context.Context, gvk schema.GroupVersionKind, opts ...cache.InformerGetOption) (cache.Informer, error) {
+	inf, err := c.Cache.GetInformerForKind(ctx, gvk, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return &ScopedInformer{clusterName: c.clusterName, Informer: inf}, nil
+}
+
+func (c *NamespacedCache) RemoveInformer(ctx context.Context, obj client.Object) error {
+	return errors.New("informer cannot be removed from scoped cache")
+}
+
+type ScopedInformer struct {
+	clusterName string
+	cache.Informer
+}
+
+func (i *ScopedInformer) AddEventHandler(handler toolscache.ResourceEventHandler) (toolscache.ResourceEventHandlerRegistration, error) {
+	return i.Informer.AddEventHandler(toolscache.ResourceEventHandlerDetailedFuncs{
+		AddFunc: func(obj interface{}, isInInitialList bool) {
+			cobj := obj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnAdd(cobj, isInInitialList)
+			}
+		},
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			cobj := newObj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnUpdate(oldObj, cobj)
+			}
+		},
+		DeleteFunc: func(obj interface{}) {
+			if tombStone, ok := obj.(toolscache.DeletedFinalStateUnknown); ok {
+				obj = tombStone.Obj
+			}
+			cobj := obj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnDelete(cobj)
+			}
+		},
+	})
+}
+
+func (i *ScopedInformer) AddEventHandlerWithResyncPeriod(handler toolscache.ResourceEventHandler, resyncPeriod time.Duration) (toolscache.ResourceEventHandlerRegistration, error) {
+	return i.Informer.AddEventHandlerWithResyncPeriod(toolscache.ResourceEventHandlerDetailedFuncs{
+		AddFunc: func(obj interface{}, isInInitialList bool) {
+			cobj := obj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnAdd(cobj, isInInitialList)
+			}
+		},
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			cobj := newObj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnUpdate(oldObj, cobj)
+			}
+		},
+		DeleteFunc: func(obj interface{}) {
+			if tombStone, ok := obj.(toolscache.DeletedFinalStateUnknown); ok {
+				obj = tombStone.Obj
+			}
+			cobj := obj.(client.Object)
+			if cobj.GetNamespace() == i.clusterName {
+				cobj := cobj.DeepCopyObject().(client.Object)
+				cobj.SetNamespace("default")
+				handler.OnDelete(cobj)
+			}
+		},
+	}, resyncPeriod)
+}
+
+func (i *ScopedInformer) AddIndexers(indexers toolscache.Indexers) error {
+	return errors.New("indexes cannot be added to scoped informers")
+}
+
+type NamespaceScopeableCache struct {
+	cache.Cache
+}
+
+func (f *NamespaceScopeableCache) IndexField(ctx context.Context, obj client.Object, field string, extractValue client.IndexerFunc) error {
+	return f.IndexField(ctx, obj, "cluster/"+field, func(obj client.Object) []string {
+		keys := extractValue(obj)
+		withCluster := make([]string, len(keys)*2)
+		for i, key := range keys {
+			withCluster[i] = fmt.Sprintf("%s/%s", obj.GetNamespace(), key)
+			withCluster[i+len(keys)] = fmt.Sprintf("*/%s", key)
+		}
+		return withCluster
+	})
+}
+
+func (f *NamespaceScopeableCache) Start(ctx context.Context) error {
+	return nil // no-op as this is shared
+}

examples/fleet-namespace/client.go

@@ -0,0 +1,91 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+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 main
+
+import (
+	"context"
+
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+)
+
+var _ client.Client = &NamespacedClient{}
+
+type NamespacedClient struct {
+	clusterName string
+	client.Client
+}
+
+func (n *NamespacedClient) Get(ctx context.Context, key client.ObjectKey, obj client.Object, opts ...client.GetOption) error {
+	if key.Namespace != "default" {
+		return apierrors.NewNotFound(schema.GroupResource{}, key.Name)
+	}
+	key.Namespace = n.clusterName
+	if err := n.Client.Get(ctx, key, obj, opts...); err != nil {
+		return err
+	}
+	obj.SetNamespace("default")
+	return nil
+}
+
+func (n *NamespacedClient) List(ctx context.Context, list client.ObjectList, opts ...client.ListOption) error {
+	var copts client.ListOptions
+	for _, o := range opts {
+		o.ApplyToList(&copts)
+	}
+	if copts.Namespace != "default" {
+		return apierrors.NewNotFound(schema.GroupResource{}, copts.Namespace)
+	}
+	if err := n.Client.List(ctx, list, append(opts, client.InNamespace(n.clusterName))...); err != nil {
+		return err
+	}
+	return meta.EachListItem(list, func(obj runtime.Object) error {
+		obj.(client.Object).SetNamespace("default")
+		return nil
+	})
+}
+
+func (n *NamespacedClient) Create(ctx context.Context, obj client.Object, opts ...client.CreateOption) error {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) Delete(ctx context.Context, obj client.Object, opts ...client.DeleteOption) error {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) Update(ctx context.Context, obj client.Object, opts ...client.UpdateOption) error {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) Patch(ctx context.Context, obj client.Object, patch client.Patch, opts ...client.PatchOption) error {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) DeleteAllOf(ctx context.Context, obj client.Object, opts ...client.DeleteAllOfOption) error {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) Status() client.SubResourceWriter {
+	panic("implement me")
+}
+
+func (n *NamespacedClient) SubResource(subResource string) client.SubResourceClient {
+	panic("implement me")
+}

examples/fleet-namespace/cluster.go

@@ -0,0 +1,55 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+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 main
+
+import (
+	"context"
+
+	"k8s.io/client-go/tools/record"
+	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+)
+
+type NamespacedCluster struct {
+	clusterName string
+	cluster.Cluster
+}
+
+func (c *NamespacedCluster) Name() string {
+	return c.clusterName
+}
+
+func (c *NamespacedCluster) GetCache() cache.Cache {
+	return &NamespacedCache{clusterName: c.clusterName, Cache: c.Cluster.GetCache()}
+}
+
+func (c *NamespacedCluster) GetClient() client.Client {
+	return &NamespacedClient{clusterName: c.clusterName, Client: c.Cluster.GetClient()}
+}
+
+func (c *NamespacedCluster) GetEventRecorderFor(name string) record.EventRecorder {
+	panic("implement me")
+}
+
+func (c *NamespacedCluster) GetAPIReader() client.Reader {
+	return c.GetClient()
+}
+
+func (c *NamespacedCluster) Start(ctx context.Context) error {
+	return nil // no-op as this is shared
+}