Add KCP helpers for creating new managers/clients/caches

pkg/kcp/wrappers.go

@@ -0,0 +1,86 @@
+/*
+Copyright 2022 The KCP 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 kcp
+
+import (
+	"net/http"
+
+	"k8s.io/client-go/rest"
+
+	kcpcache "github.com/kcp-dev/apimachinery/pkg/cache"
+	kcpclient "github.com/kcp-dev/apimachinery/pkg/client"
+
+	ctrl "sigs.k8s.io/controller-runtime"
+	"sigs.k8s.io/controller-runtime/pkg/cache"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/cluster"
+	"sigs.k8s.io/controller-runtime/pkg/manager"
+)
+
+// NewClusterAwareManager returns a kcp-aware manager with appropriate defaults for cache and
+// client creation.
+func NewClusterAwareManager(cfg *rest.Config, options ctrl.Options) (manager.Manager, error) {
+	if options.NewCache == nil {
+		options.NewCache = NewClusterAwareCache
+	}
+	if options.NewClient == nil {
+		options.NewClient = NewClusterAwareClient
+	}
+
+	return ctrl.NewManager(cfg, options)
+}
+
+// NewClusterAwareCache returns a cache.Cache that handles multi-cluster watches.
+func NewClusterAwareCache(config *rest.Config, opts cache.Options) (cache.Cache, error) {
+	c := rest.CopyConfig(config)
+	c.Host += "/clusters/*"
+	opts.KeyFunction = kcpcache.ClusterAwareKeyFunc
+	return cache.New(c, opts)
+}
+
+// NewClusterAwareClient returns a client.Client that is configured to use the context
+// to scope requests to the proper cluster. To scope requests, pass the request context with the cluster set.
+// Example:
+//	import (
+//		"context"
+//		kcpclient "github.com/kcp-dev/apimachinery/pkg/client"
+//		ctrl "sigs.k8s.io/controller-runtime"
+//	)
+//	func (r *reconciler)  Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
+//		ctx = kcpclient.WithCluster(ctx, req.ObjectKey.Cluster)
+//		// from here on pass this context to all client calls
+//		...
+//	}
+func NewClusterAwareClient(cache cache.Cache, config *rest.Config, opts client.Options, uncachedObjects ...client.Object) (client.Client, error) {
+	httpClient, err := ClusterAwareHTTPClient(config)
+	if err != nil {
+		return nil, err
+	}
+	opts.HTTPClient = httpClient
+	return cluster.DefaultNewClient(cache, config, opts, uncachedObjects...)
+}
+
+// ClusterAwareHTTPClient returns an http.Client with a cluster aware round tripper.
+func ClusterAwareHTTPClient(config *rest.Config) (*http.Client, error) {
+	httpClient, err := rest.HTTPClientFor(config)
+	if err != nil {
+		return nil, err
+	}
+
+	httpClient.Transport = kcpclient.NewClusterRoundTripper(httpClient.Transport)
+	return httpClient, nil
+}