Add multi provider

Author: ntnn

providers/multi/provider.go

@@ -0,0 +1,156 @@
+/*
+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 multi
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+	"sync"
+
+	"github.com/go-logr/logr"
+
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+	"sigs.k8s.io/controller-runtime/pkg/log"
+
+	mctrl "sigs.k8s.io/multicluster-runtime"
+	"sigs.k8s.io/multicluster-runtime/pkg/multicluster"
+)
+
+var _ multicluster.Provider = &Provider{}
+
+// Options defines the options for the provider.
+type Options struct {
+	Separator string
+}
+
+// Provider is a multicluster.Provider that manages multiple providers.
+type Provider struct {
+	opts Options
+
+	log logr.Logger
+	mgr mctrl.Manager
+
+	providerLock   sync.RWMutex
+	providers      map[string]multicluster.Provider
+	providerCancel map[string]context.CancelFunc
+}
+
+// New returns a new instance of the provider with the given options.
+func New(mgr mctrl.Manager, opts Options) *Provider {
+	p := new(Provider)
+
+	p.opts = opts
+	if p.opts.Separator == "" {
+		p.opts.Separator = "#"
+	}
+
+	p.log = log.Log.WithName("namespaced-cluster-provider")
+	p.mgr = mgr
+
+	p.providers = make(map[string]multicluster.Provider)
+	p.providerCancel = make(map[string]context.CancelFunc)
+
+	return p
+}
+
+// Run starts the provider and blocks until the context is done. This is a noop.
+func (p *Provider) Run(ctx context.Context, mgr mctrl.Manager) error {
+	<-ctx.Done()
+	return nil
+}
+
+func (p *Provider) splitClusterName(clusterName string) (string, string) {
+	parts := strings.SplitN(clusterName, p.opts.Separator, 2)
+	if len(parts) < 2 {
+		return "", clusterName
+	}
+	return parts[0], parts[1]
+}
+
+// AddProvider adds a new provider to the manager. The startFunc is
+// called to start the provider.
+// Starting the provider outside of this function is an error and will
+// result in undefined behaviour.
+// startFunc should not block.
+func (p *Provider) AddProvider(ctx context.Context, prefix string, provider multicluster.Provider, startFunc func(context.Context, mctrl.Manager) error) error {
+	ctx, cancel := context.WithCancel(ctx)
+
+	wrappedMgr := &wrappedManager{
+		Manager: p.mgr,
+		prefix:  prefix,
+		sep:     p.opts.Separator,
+	}
+
+	if err := startFunc(ctx, wrappedMgr); err != nil {
+		cancel()
+		return fmt.Errorf("failed to start provider %q: %w", prefix, err)
+	}
+
+	p.providerLock.Lock()
+	p.providers[prefix] = provider
+	p.providerCancel[prefix] = cancel
+	p.providerLock.Unlock()
+
+	return nil
+}
+
+// RemoveProvider removes a provider from the manager and cancels its
+// context.
+func (p *Provider) RemoveProvider(prefix string) {
+	p.providerLock.Lock()
+	defer p.providerLock.Unlock()
+	if cancel, ok := p.providerCancel[prefix]; ok {
+		cancel()
+		delete(p.providers, prefix)
+		delete(p.providerCancel, prefix)
+	}
+}
+
+// Get returns a cluster for the given identifying cluster name.
+func (p *Provider) Get(ctx context.Context, clusterName string) (cluster.Cluster, error) {
+	prefix, clusterName := p.splitClusterName(clusterName)
+
+	p.providerLock.RLock()
+	provider, ok := p.providers[prefix]
+	p.providerLock.RUnlock()
+
+	if !ok {
+		return nil, fmt.Errorf("provider not found %q: %w", prefix, multicluster.ErrClusterNotFound)
+	}
+
+	return provider.Get(ctx, clusterName)
+}
+
+// IndexField indexes the given object by the given field on all
+// providers and returns the aggregated errors.
+func (p *Provider) IndexField(ctx context.Context, obj client.Object, field string, extractValue client.IndexerFunc) error {
+	p.providerLock.RLock()
+	defer p.providerLock.RUnlock()
+	var errs error
+	for prefix, provider := range p.providers {
+		if err := provider.IndexField(ctx, obj, field, extractValue); err != nil {
+			errs = errors.Join(
+				errs,
+				fmt.Errorf("failed to index field %q on cluster %q: %w", field, prefix, err),
+			)
+		}
+	}
+	return errs
+}

providers/multi/wrappedManager.go

@@ -0,0 +1,20 @@
+package multi
+
+import (
+	"context"
+
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+
+	mctrl "sigs.k8s.io/multicluster-runtime"
+)
+
+var _ mctrl.Manager = &wrappedManager{}
+
+type wrappedManager struct {
+	mctrl.Manager
+	prefix, sep string
+}
+
+func (w *wrappedManager) Engage(ctx context.Context, name string, cl cluster.Cluster) error {
+	return w.Manager.Engage(ctx, w.prefix+w.sep+name, cl)
+}