feat: allow configuring reconciliation concurrency

main.go

@@ -59,11 +59,15 @@ func main() {
 	var metricsAddr string
 	var enableLeaderElection bool
 	var probeAddr string
+	var maxConcurrentReconciles int
 	flag.StringVar(&metricsAddr, "metrics-bind-address", ":8080", "The address the metric endpoint binds to.")
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
 	flag.BoolVar(&enableLeaderElection, "leader-elect", false,
 		"Enable leader election for controller manager. "+
 			"Enabling this will ensure there is only one active controller manager.")
+	flag.IntVar(&maxConcurrentReconciles, "max-concurrent-reconciles", 1,
+		"The maximum number of concurrent Reconciles which can be run.",
+	)
 	opts := zap.Options{
 		Development: false,
 	}
@@ -111,7 +115,7 @@ func main() {
 		Log:             ctrl.Log.WithName("controllers").WithName("EndpointMonitor"),
 		Scheme:          mgr.GetScheme(),
 		MonitorServices: monitors.SetupMonitorServicesForProviders(config.Providers),
-	}).SetupWithManager(mgr); err != nil {
+	}).SetupWithManager(mgr, maxConcurrentReconciles); err != nil {
 		setupLog.Error(err, "unable to create controller", "controller", "EndpointMonitor")
 		os.Exit(1)
 	}

pkg/controllers/endpointmonitor_controller.go

@@ -29,6 +29,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	ctrl "sigs.k8s.io/controller-runtime"
 	"sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/controller"
 	logf "sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/reconcile"
 
@@ -105,8 +106,11 @@ func (r *EndpointMonitorReconciler) Reconcile(ctx context.Context, req ctrl.Requ
 }
 
 // SetupWithManager sets up the controller with the Manager.
-func (r *EndpointMonitorReconciler) SetupWithManager(mgr ctrl.Manager) error {
+func (r *EndpointMonitorReconciler) SetupWithManager(mgr ctrl.Manager, maxConcurrentReconciles int) error {
 	return ctrl.NewControllerManagedBy(mgr).
+		WithOptions(controller.Options{
+			MaxConcurrentReconciles: maxConcurrentReconciles,
+		}).
 		For(&endpointmonitorv1alpha1.EndpointMonitor{}).
 		Complete(r)
 }