Delay informer start after controller.

Starting informer before controller will cause resync period set
in the informer not respected, this commit makes EnableInjectionOrDie
to return informers so that the callers can delay the start of the
informer.

injection/sharedmain/main.go

@@ -129,7 +129,7 @@ func GetLeaderElectionConfig(ctx context.Context) (*leaderelection.Config, error
 
 // EnableInjectionOrDie enables Knative Injection and starts the informers.
 // Both Context and Config are optional.
-func EnableInjectionOrDie(ctx context.Context, cfg *rest.Config) context.Context {
+func EnableInjectionOrDie(ctx context.Context, cfg *rest.Config) (context.Context, []controller.Informer) {
 	if ctx == nil {
 		ctx = signals.NewContext()
 	}
@@ -146,18 +146,7 @@ func EnableInjectionOrDie(ctx context.Context, cfg *rest.Config) context.Context
 	}
 	ctx = injection.WithConfig(ctx, cfg)
 
-	ctx, informers := injection.Default.SetupInformers(ctx, cfg)
-
-	// Start the injection clients and informers.
-	logging.FromContext(ctx).Info("Starting informers...")
-	go func(ctx context.Context) {
-		if err := controller.StartInformers(ctx.Done(), informers...); err != nil {
-			logging.FromContext(ctx).Fatalw("Failed to start informers", zap.Error(err))
-		}
-		<-ctx.Done()
-	}(ctx)
-
-	return ctx
+	return injection.Default.SetupInformers(ctx, cfg)
 }
 
 // Main runs the generic main flow with a new context.
@@ -225,7 +214,7 @@ func MainWithConfig(ctx context.Context, component string, cfg *rest.Config, cto
 		cfg.Burst = len(ctors) * rest.DefaultBurst
 	}
 
-	ctx = EnableInjectionOrDie(ctx, cfg)
+	ctx, informers := EnableInjectionOrDie(ctx, cfg)
 
 	logger, atomicLevel := SetupLoggerOrDie(ctx, component)
 	defer flush(logger)
@@ -279,6 +268,14 @@ func MainWithConfig(ctx context.Context, component string, cfg *rest.Config, cto
 		})
 	}
 
+	// Start the injection clients and informers.
+	logging.FromContext(ctx).Info("Starting informers...")
+	go func(ctx context.Context) {
+		if err := controller.StartInformers(ctx.Done(), informers...); err != nil {
+			logging.FromContext(ctx).Fatalw("Failed to start informers", zap.Error(err))
+		}
+		<-ctx.Done()
+	}(ctx)
 	// Wait for webhook informers to sync.
 	if wh != nil {
 		wh.InformersHaveSynced()

leaderelection/chaosduck/main.go

@@ -33,6 +33,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/wait"
 	"k8s.io/client-go/kubernetes"
 	kubeclient "knative.dev/pkg/client/injection/kube/client"
+	"knative.dev/pkg/controller"
 	"knative.dev/pkg/injection/sharedmain"
 	"knative.dev/pkg/kflag"
 	"knative.dev/pkg/signals"
@@ -117,8 +118,10 @@ func quack(ctx context.Context, kc kubernetes.Interface, component string, leade
 
 func main() {
 	ctx := signals.NewContext()
-	ctx = sharedmain.EnableInjectionOrDie(ctx, nil)
-
+	ctx, informers := sharedmain.EnableInjectionOrDie(ctx, nil)
+	if err := controller.StartInformers(ctx.Done(), informers...); err != nil {
+		log.Fatalf("Failed to start informers %v", err)
+	}
 	kc := kubeclient.Get(ctx)
 
 	// Until we are shutdown, build up an index of components and kill