🌱 Fixups to error when source.Start never returns

Addresses the comments on #2997

Author: alvaroaleman

pkg/internal/controller/controller.go

@@ -171,14 +171,15 @@ func (c *Controller[request]) Start(ctx context.Context) error {
 		defer utilruntime.HandleCrash()
 
 		// NB(directxman12): launch the sources *before* trying to wait for the
-		// caches to sync so that they have a chance to register their intendeded
+		// caches to sync so that they have a chance to register their intended
 		// caches.
 		errGroup := &errgroup.Group{}
 		for _, watch := range c.startWatches {
 			log := c.LogConstructor(nil).WithValues("source", fmt.Sprintf("%s", watch))
 			didStartSyncingSource := &atomic.Bool{}
 			errGroup.Go(func() error {
-				// use a context with timeout for launching sources and syncing caches.
+				// Use a timeout for starting and syncing the source to avoid silently
+				// blocking startup indefinitely if it doesn't come up.
 				sourceStartCtx, cancel := context.WithTimeout(ctx, c.CacheSyncTimeout)
 				defer cancel()
 
@@ -220,7 +221,6 @@ func (c *Controller[request]) Start(ctx context.Context) error {
 			return err
 		}
 
-		// Start the SharedIndexInformer factories to begin populating the SharedIndexInformer caches
 		c.LogConstructor(nil).Info("Starting Controller")
 
 		// All the watches have been started, we can reset the local slice.

pkg/internal/controller/controller_test.go

@@ -201,7 +201,7 @@ var _ = Describe("controller", func() {
 		})
 
 		It("should error when Start() is blocking forever", func() {
-			ctrl.CacheSyncTimeout = 0
+			ctrl.CacheSyncTimeout = time.Second
 
 			controllerDone := make(chan struct{})
 			ctrl.startWatches = []source.TypedSource[reconcile.Request]{
@@ -304,7 +304,7 @@ var _ = Describe("controller", func() {
 				Expect(q).To(Equal(ctrl.Queue))
 
 				started = true
-				cancel()
+				cancel() // Cancel the context so ctrl.Start() doesn't block forever
 				return nil
 			})
 			Expect(ctrl.Watch(src)).NotTo(HaveOccurred())