Pre-factor server.go

- No functional changes
- Move all the stuff about clients and controllers into the controller
  package
- Add more comments and organize the code more into more helper
  functions to make each function smaller

internal/controller/prepare_controllers.go

@@ -0,0 +1,139 @@
+/*
+Copyright 2020 VMware, Inc.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package controller
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	k8sinformers "k8s.io/client-go/informers"
+	"k8s.io/client-go/kubernetes"
+	restclient "k8s.io/client-go/rest"
+	aggregationv1client "k8s.io/kube-aggregator/pkg/client/clientset_generated/clientset"
+
+	"github.com/suzerain-io/controller-go"
+	"github.com/suzerain-io/placeholder-name/internal/autoregistration"
+	"github.com/suzerain-io/placeholder-name/internal/controller/logindiscovery"
+	placeholderclientset "github.com/suzerain-io/placeholder-name/kubernetes/1.19/client-go/clientset/versioned"
+	placeholderinformers "github.com/suzerain-io/placeholder-name/kubernetes/1.19/client-go/informers/externalversions"
+)
+
+const (
+	singletonWorker       = 1
+	defaultResyncInterval = 3 * time.Minute
+)
+
+// Prepare the controllers and their informers and return a function that will start them when called.
+func PrepareControllers(
+	ctx context.Context,
+	caBundle []byte,
+	serverInstallationNamespace string,
+	discoveryURLOverride *string,
+) (func(ctx context.Context), error) {
+	// Create k8s clients.
+	k8sClient, aggregationClient, placeholderClient, err := createClients()
+	if err != nil {
+		return nil, fmt.Errorf("could not create clients for the controllers: %w", err)
+	}
+
+	// TODO Putting this here temporarily on the way toward moving it elsewhere.
+	//  When it moves elsewhere then PrepareControllers() will not need to take ctx and caBundle parameters.
+	if err := autoregistration.UpdateAPIService(ctx, aggregationClient, caBundle); err != nil {
+		return nil, fmt.Errorf("could not update the API service: %w", err)
+	}
+
+	// Create informers.
+	k8sInformers, placeholderInformers := createInformers(serverInstallationNamespace, k8sClient, placeholderClient)
+
+	// Create controller manager.
+	controllerManager := controller.
+		NewManager().
+		WithController(
+			logindiscovery.NewPublisherController(
+				serverInstallationNamespace,
+				discoveryURLOverride,
+				placeholderClient,
+				k8sInformers.Core().V1().ConfigMaps(),
+				placeholderInformers.Crds().V1alpha1().LoginDiscoveryConfigs(),
+				controller.WithInformer,
+			),
+			singletonWorker,
+		)
+
+	// Return a function which starts the informers and controllers.
+	return func(ctx context.Context) {
+		k8sInformers.Start(ctx.Done())
+		placeholderInformers.Start(ctx.Done())
+		go controllerManager.Start(ctx)
+	}, nil
+}
+
+// Create the k8s clients that will be used by the controllers.
+func createClients() (*kubernetes.Clientset, *aggregationv1client.Clientset, *placeholderclientset.Clientset, error) {
+	// Load the Kubernetes client configuration (kubeconfig),
+	kubeConfig, err := restclient.InClusterConfig()
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("could not load in-cluster configuration: %w", err)
+	}
+
+	// explicitly use protobuf when talking to built-in kube APIs
+	protoKubeConfig := createProtoKubeConfig(kubeConfig)
+
+	// Connect to the core Kubernetes API.
+	k8sClient, err := kubernetes.NewForConfig(protoKubeConfig)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("could not initialize Kubernetes client: %w", err)
+	}
+
+	// Connect to the Kubernetes aggregation API.
+	aggregationClient, err := aggregationv1client.NewForConfig(protoKubeConfig)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("could not initialize Kubernetes client: %w", err)
+	}
+
+	// Connect to the placeholder API.
+	// I think we can't use protobuf encoding here because we are using CRDs
+	// (for which protobuf encoding is not supported).
+	placeholderClient, err := placeholderclientset.NewForConfig(kubeConfig)
+	if err != nil {
+		return nil, nil, nil, fmt.Errorf("could not initialize placeholder client: %w", err)
+	}
+
+	return k8sClient, aggregationClient, placeholderClient, nil
+}
+
+// Create the informers that will be used by the controllers.
+func createInformers(
+	serverInstallationNamespace string,
+	k8sClient *kubernetes.Clientset,
+	placeholderClient *placeholderclientset.Clientset,
+) (k8sinformers.SharedInformerFactory, placeholderinformers.SharedInformerFactory) {
+	k8sInformers := k8sinformers.NewSharedInformerFactoryWithOptions(
+		k8sClient,
+		defaultResyncInterval,
+		k8sinformers.WithNamespace(
+			logindiscovery.ClusterInfoNamespace,
+		),
+	)
+	placeholderInformers := placeholderinformers.NewSharedInformerFactoryWithOptions(
+		placeholderClient,
+		defaultResyncInterval,
+		placeholderinformers.WithNamespace(serverInstallationNamespace),
+	)
+	return k8sInformers, placeholderInformers
+}
+
+// Returns a copy of the input config with the ContentConfig set to use protobuf.
+// Do not use this config to communicate with any CRD based APIs.
+func createProtoKubeConfig(kubeConfig *restclient.Config) *restclient.Config {
+	protoKubeConfig := restclient.CopyConfig(kubeConfig)
+	const protoThenJSON = runtime.ContentTypeProtobuf + "," + runtime.ContentTypeJSON
+	protoKubeConfig.AcceptContentTypes = protoThenJSON
+	protoKubeConfig.ContentType = runtime.ContentTypeProtobuf
+	return protoKubeConfig
+}