Add multi provider

Signed-off-by: Nelo-T. Wallus <[email protected]>

Author: ntnn

providers/multi/doc.go

@@ -0,0 +1,23 @@
+/*
+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 provides a multicluster.Provider that allows to utilize
+// multiple providers in a single multicluster.Manager without
+// conflicting cluster names.
+//
+// Each provider must be added with a unique prefix, which is used to
+// identify clusters generated by that provider.
+package multi

providers/multi/multi_suite_test.go

@@ -0,0 +1,87 @@
+/*
+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 (
+	"testing"
+
+	"k8s.io/client-go/rest"
+
+	"sigs.k8s.io/controller-runtime/pkg/envtest"
+	logf "sigs.k8s.io/controller-runtime/pkg/log"
+	"sigs.k8s.io/controller-runtime/pkg/log/zap"
+	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestBuilder(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Namespace Provider Suite")
+}
+
+// The operator runs in a local cluster and embeds two other providers
+// for cloud providers. The cloud providers are simulated by using the
+// namespace provider with two other clusters.
+
+var localEnv *envtest.Environment
+var localCfg *rest.Config
+
+var cloud1 *envtest.Environment
+var cloud1cfg *rest.Config
+
+var cloud2 *envtest.Environment
+var cloud2cfg *rest.Config
+
+var _ = BeforeSuite(func() {
+	logf.SetLogger(zap.New(zap.WriteTo(GinkgoWriter), zap.UseDevMode(true)))
+
+	var err error
+
+	localEnv = &envtest.Environment{}
+	localCfg, err = localEnv.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	cloud1 = &envtest.Environment{}
+	cloud1cfg, err = cloud1.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	cloud2 = &envtest.Environment{}
+	cloud2cfg, err = cloud2.Start()
+	Expect(err).NotTo(HaveOccurred())
+
+	// Prevent the metrics listener being created
+	metricsserver.DefaultBindAddress = "0"
+})
+
+var _ = AfterSuite(func() {
+	if localEnv != nil {
+		Expect(localEnv.Stop()).To(Succeed())
+	}
+
+	if cloud1 != nil {
+		Expect(cloud1.Stop()).To(Succeed())
+	}
+
+	if cloud2 != nil {
+		Expect(cloud2.Stop()).To(Succeed())
+	}
+
+	// Put the DefaultBindAddress back
+	metricsserver.DefaultBindAddress = ":8080"
+})

providers/multi/provider.go

@@ -0,0 +1,180 @@
+/*
+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(opts Options) *Provider {
+	p := new(Provider)
+
+	p.opts = opts
+	if p.opts.Separator == "" {
+		p.opts.Separator = "#"
+	}
+
+	p.log = log.Log.WithName("multi-provider")
+
+	p.providers = make(map[string]multicluster.Provider)
+	p.providerCancel = make(map[string]context.CancelFunc)
+
+	return p
+}
+
+// SetManager sets the manager for the provider.
+func (p *Provider) SetManager(mgr mctrl.Manager) {
+	if p.mgr != nil {
+		p.log.Error(nil, "manager already set, overwriting")
+	}
+	p.mgr = mgr
+}
+
+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 with the given prefix.
+//
+// The startFunc is called to start the provider - starting the provider
+// outside of startFunc is an error and will result in undefined
+// behaviour.
+// startFunc should block for as long as the provider is running,
+// If startFunc returns an error the provider is removed and the error
+// is returned.
+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)
+
+	p.providerLock.Lock()
+	_, ok := p.providers[prefix]
+	p.providerLock.Unlock()
+	if ok {
+		cancel()
+		return fmt.Errorf("provider already exists for prefix %q", prefix)
+	}
+
+	var wrappedMgr mctrl.Manager
+	if p.mgr == nil {
+		p.log.Info("manager is nil, wrapped manager passed to start will be nil as well", "prefix", prefix)
+	} else {
+		wrappedMgr = &wrappedManager{
+			Manager: p.mgr,
+			prefix:  prefix,
+			sep:     p.opts.Separator,
+		}
+	}
+
+	p.providerLock.Lock()
+	p.providers[prefix] = provider
+	p.providerCancel[prefix] = cancel
+	p.providerLock.Unlock()
+
+	go func() {
+		defer p.RemoveProvider(prefix)
+		if err := startFunc(ctx, wrappedMgr); err != nil {
+			cancel()
+			p.log.Error(err, "error in provider", "prefix", prefix)
+		}
+	}()
+
+	return nil
+}
+
+// RemoveProvider removes a provider from the manager and cancels its
+// context.
+//
+// Warning: This can lead to dangling clusters if the provider is not
+// using the context it is started with to engage the clusters it
+// manages.
+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 by 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 a field  on all providers and clusters 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
+}