providers: unify constructors and runner

Signed-off-by: Dr. Stefan Schimanski <[email protected]>

Author: sttts

providers/kind/provider.go

@@ -24,6 +24,7 @@ import (
 	"time"
 
 	"github.com/go-logr/logr"
+
 	mcmanager "github.com/multicluster-runtime/multicluster-runtime/pkg/manager"
 	"github.com/multicluster-runtime/multicluster-runtime/pkg/multicluster"
 	"k8s.io/apimachinery/pkg/util/sets"
@@ -34,6 +35,8 @@ import (
 	kind "sigs.k8s.io/kind/pkg/cluster"
 )
 
+var _ multicluster.Provider = &Provider{}
+
 // New creates a new kind cluster Provider.
 func New() *Provider {
 	return &Provider{
@@ -52,8 +55,7 @@ type Provider struct {
 	cancelFns map[string]context.CancelFunc
 }
 
-var _ multicluster.Provider = &Provider{}
-
+// Get returns the cluster with the given name, if it is known.
 func (k *Provider) Get(ctx context.Context, clusterName string) (cluster.Cluster, error) {
 	k.lock.RLock()
 	defer k.lock.RUnlock()
@@ -64,6 +66,7 @@ func (k *Provider) Get(ctx context.Context, clusterName string) (cluster.Cluster
 	return nil, fmt.Errorf("cluster %s not found", clusterName)
 }
 
+// Run starts the provider and blocks.
 func (k *Provider) Run(ctx context.Context, mgr mcmanager.Manager) error {
 	k.log.Info("Starting kind cluster Provider")
 

providers/namespace/provider.go

@@ -22,6 +22,8 @@ import (
 	"sync"
 
 	"github.com/go-logr/logr"
+	"github.com/multicluster-runtime/multicluster-runtime/pkg/multicluster"
+
 	mcmanager "github.com/multicluster-runtime/multicluster-runtime/pkg/manager"
 	corev1 "k8s.io/api/core/v1"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
@@ -31,11 +33,13 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 )
 
-// NamespacedClusterProvider is a cluster provider that represents each namespace
+var _ multicluster.Provider = &Provider{}
+
+// Provider is a cluster provider that represents each namespace
 // as a dedicated cluster with only a "default" namespace. It maps each namespace
 // to "default" and vice versa, simulating a multi-cluster setup. It uses one
 // informer to watch objects for all namespaces.
-type NamespacedClusterProvider struct {
+type Provider struct {
 	cluster cluster.Cluster
 
 	mgr manager.Manager
@@ -46,16 +50,17 @@ type NamespacedClusterProvider struct {
 	cancelFns map[string]context.CancelFunc
 }
 
-func NewNamespacedClusterProvider(cl cluster.Cluster) *NamespacedClusterProvider {
-	return &NamespacedClusterProvider{
+func New(cl cluster.Cluster) *Provider {
+	return &Provider{
 		cluster:   cl,
 		log:       log.Log.WithName("namespaced-cluster-provider"),
 		clusters:  map[string]cluster.Cluster{},
 		cancelFns: map[string]context.CancelFunc{},
 	}
 }
 
-func (p *NamespacedClusterProvider) Start(ctx context.Context, mgr mcmanager.Manager) error {
+// Run starts the provider and blocks.
+func (p *Provider) Run(ctx context.Context, mgr mcmanager.Manager) error {
 	nsInf, err := p.cluster.GetCache().GetInformer(ctx, &corev1.Namespace{})
 	if err != nil {
 		return err
@@ -116,10 +121,12 @@ func (p *NamespacedClusterProvider) Start(ctx context.Context, mgr mcmanager.Man
 		return err
 	}
 
+	<-ctx.Done()
+
 	return nil
 }
 
-func (p *NamespacedClusterProvider) Get(ctx context.Context, clusterName string) (cluster.Cluster, error) {
+func (p *Provider) Get(ctx context.Context, clusterName string) (cluster.Cluster, error) {
 	p.lock.RLock()
 	defer p.lock.RUnlock()
 	if cl, ok := p.clusters[clusterName]; ok {

providers/nop/provider.go

@@ -0,0 +1,47 @@
+/*
+Copyright 2025 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 namespace
+
+import (
+	"context"
+	"fmt"
+
+	mcmanager "github.com/multicluster-runtime/multicluster-runtime/pkg/manager"
+	"github.com/multicluster-runtime/multicluster-runtime/pkg/multicluster"
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+)
+
+var _ multicluster.Provider = &Provider{}
+
+// Provider is a provider that does nothing.
+type Provider struct{}
+
+// New creates a new provider that does nothing.
+func New() *Provider {
+	return &Provider{}
+}
+
+// Run starts the provider and blocks.
+func (p *Provider) Run(ctx context.Context, _ mcmanager.Manager) error {
+	<-ctx.Done()
+	return nil
+}
+
+// Get returns an error for any cluster name.
+func (p *Provider) Get(_ context.Context, clusterName string) (cluster.Cluster, error) {
+	return nil, fmt.Errorf("cluster %s not found", clusterName)
+}

providers/single/provider.go

@@ -0,0 +1,57 @@
+/*
+Copyright 2025 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 namespace
+
+import (
+	"context"
+	"fmt"
+
+	mcmanager "github.com/multicluster-runtime/multicluster-runtime/pkg/manager"
+	"github.com/multicluster-runtime/multicluster-runtime/pkg/multicluster"
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+)
+
+var _ multicluster.Provider = &Provider{}
+
+// Provider is a provider that engages the passed cluster.
+type Provider struct {
+	name string
+	cl   cluster.Cluster
+}
+
+// New returns a provider engaging the passed cluster under the given name.
+// It does not start the passed cluster.
+func New(name string, cl cluster.Cluster) *Provider {
+	return &Provider{
+		name: name,
+		cl:   cl,
+	}
+}
+
+// Run starts the provider and blocks.
+func (p *Provider) Run(ctx context.Context, _ mcmanager.Manager) error {
+	<-ctx.Done()
+	return nil
+}
+
+// Get returns the cluster with the given name.
+func (p *Provider) Get(_ context.Context, clusterName string) (cluster.Cluster, error) {
+	if clusterName == p.name {
+		return p.cl, nil
+	}
+	return nil, fmt.Errorf("cluster %s not found", clusterName)
+}