Fix up example to make use of logr

The example sets up logr, and then uses the built-in go `log` package.
We should show people how to make use of logr instead.

Author: DirectXMan12

example/main.go

@@ -19,8 +19,9 @@ package main
 import (
 	"context"
 	"flag"
-	"log"
+	"os"
 
+	"github.com/go-logr/logr"
 	appsv1 "k8s.io/api/apps/v1"
 	corev1 "k8s.io/api/core/v1"
 	"k8s.io/apimachinery/pkg/api/errors"
@@ -36,63 +37,78 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/source"
 )
 
+var (
+	log = logf.Log.WithName("example-controller")
+)
+
 func main() {
 	flag.Parse()
 	logf.SetLogger(logf.ZapLogger(false))
+	entryLog := log.WithName("entrypoint")
 
 	// Setup a Manager
 	mrg, err := manager.New(config.GetConfigOrDie(), manager.Options{})
 	if err != nil {
-		log.Fatal(err)
+		entryLog.Error(err, "unable to set up overall controller manager")
+		os.Exit(1)
 	}
 
 	// Setup a new controller to Reconciler ReplicaSets
 	c, err := controller.New("foo-controller", mrg, controller.Options{
-		Reconciler: &reconcileReplicaSet{client: mrg.GetClient()},
+		Reconciler: &reconcileReplicaSet{client: mrg.GetClient(), log: log.WithName("reconciler")},
 	})
 	if err != nil {
-		log.Fatal(err)
+		entryLog.Error(err, "unable to set up individual controller")
+		os.Exit(1)
 	}
 
 	// Watch ReplicaSets and enqueue ReplicaSet object key
 	if err := c.Watch(&source.Kind{Type: &appsv1.ReplicaSet{}}, &handler.EnqueueRequestForObject{}); err != nil {
-		log.Fatal(err)
+		entryLog.Error(err, "unable to watch ReplicaSets")
+		os.Exit(1)
 	}
 
 	// Watch Pods and enqueue owning ReplicaSet key
 	if err := c.Watch(&source.Kind{Type: &corev1.Pod{}},
 		&handler.EnqueueRequestForOwner{OwnerType: &appsv1.ReplicaSet{}, IsController: true}); err != nil {
-		log.Fatal(err)
+		entryLog.Error(err, "unable to watch Pods")
+		os.Exit(1)
 	}
 
-	log.Fatal(mrg.Start(signals.SetupSignalHandler()))
+	if err := mrg.Start(signals.SetupSignalHandler()); err != nil {
+		entryLog.Error(err, "unable to run manager")
+		os.Exit(1)
+	}
 }
 
 // reconcileReplicaSet reconciles ReplicaSets
 type reconcileReplicaSet struct {
 	client client.Client
+	log    logr.Logger
 }
 
 // Implement reconcile.Reconciler so the controller can reconcile objects
 var _ reconcile.Reconciler = &reconcileReplicaSet{}
 
 func (r *reconcileReplicaSet) Reconcile(request reconcile.Request) (reconcile.Result, error) {
+	// set up a convinient log object so we don't have to type request over and over again
+	log := r.log.WithValues("request", request)
+
 	// Fetch the ReplicaSet from the cache
 	rs := &appsv1.ReplicaSet{}
 	err := r.client.Get(context.TODO(), request.NamespacedName, rs)
 	if errors.IsNotFound(err) {
-		log.Printf("Could not find ReplicaSet %v.\n", request)
+		log.Error(nil, "Could not find ReplicaSet")
 		return reconcile.Result{}, nil
 	}
 
 	if err != nil {
-		log.Printf("Could not fetch ReplicaSet %v for %+v\n", err, request)
+		log.Error(err, "Could not fetch ReplicaSet")
 		return reconcile.Result{}, err
 	}
 
 	// Print the ReplicaSet
-	log.Printf("ReplicaSet Name %s Namespace %s, Pod Name: %s\n",
-		rs.Name, rs.Namespace, rs.Spec.Template.Spec.Containers[0].Name)
+	log.Info("Reconciling ReplicaSet", "container name", rs.Spec.Template.Spec.Containers[0].Name)
 
 	// Set the label if it is missing
 	if rs.Labels == nil {
@@ -106,7 +122,7 @@ func (r *reconcileReplicaSet) Reconcile(request reconcile.Request) (reconcile.Re
 	rs.Labels["hello"] = "world"
 	err = r.client.Update(context.TODO(), rs)
 	if err != nil {
-		log.Printf("Could not write ReplicaSet %v\n", err)
+		log.Error(err, "Could not write ReplicaSet")
 		return reconcile.Result{}, err
 	}