Make workqueue rate limiter configurable during controller creation

Exposes rate limiter as a controller option in case users want to use
a different rate limiter than the default one provided by
controller-runtime.

Author: rajathagasthya

pkg/builder/controller_test.go

@@ -30,6 +30,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/client-go/util/workqueue"
 	"sigs.k8s.io/controller-runtime/pkg/controller"
 	"sigs.k8s.io/controller-runtime/pkg/handler"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
@@ -126,6 +127,28 @@ var _ = Describe("application", func() {
 			Expect(instance).NotTo(BeNil())
 		})
 
+		It("should override rate limiter during creation of controller", func() {
+			rateLimiter := workqueue.DefaultItemBasedRateLimiter()
+			newController = func(name string, mgr manager.Manager, options controller.Options) (controller.Controller, error) {
+				if options.RateLimiter == rateLimiter {
+					return controller.New(name, mgr, options)
+				}
+				return nil, fmt.Errorf("rate limiter expected %T but found %T", rateLimiter, options.RateLimiter)
+			}
+
+			By("creating a controller manager")
+			m, err := manager.New(cfg, manager.Options{})
+			Expect(err).NotTo(HaveOccurred())
+
+			instance, err := ControllerManagedBy(m).
+				For(&appsv1.ReplicaSet{}).
+				Owns(&appsv1.ReplicaSet{}).
+				WithOptions(controller.Options{RateLimiter: rateLimiter}).
+				Build(noop)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(instance).NotTo(BeNil())
+		})
+
 		It("should allow multiple controllers for the same kind", func() {
 			By("creating a controller manager")
 			m, err := manager.New(cfg, manager.Options{})

pkg/controller/controller.go

@@ -24,6 +24,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/internal/controller"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
 	"sigs.k8s.io/controller-runtime/pkg/predicate"
+	"sigs.k8s.io/controller-runtime/pkg/ratelimiter"
 	"sigs.k8s.io/controller-runtime/pkg/reconcile"
 	"sigs.k8s.io/controller-runtime/pkg/source"
 )
@@ -35,6 +36,11 @@ type Options struct {
 
 	// Reconciler reconciles an object
 	Reconciler reconcile.Reconciler
+
+	// RateLimiter is used to limit how frequently requests maybe queued.
+	// Defaults to MaxOfRateLimiter which has both overall and per-item rate limiting.
+	// The overall is a token bucket and the per-item is exponential.
+	RateLimiter ratelimiter.RateLimiter
 }
 
 // Controller implements a Kubernetes API.  A Controller manages a work queue fed reconcile.Requests
@@ -73,6 +79,10 @@ func New(name string, mgr manager.Manager, options Options) (Controller, error)
 		options.MaxConcurrentReconciles = 1
 	}
 
+	if options.RateLimiter == nil {
+		options.RateLimiter = workqueue.DefaultControllerRateLimiter()
+	}
+
 	// Inject dependencies into Reconciler
 	if err := mgr.SetFields(options.Reconciler); err != nil {
 		return nil, err
@@ -87,7 +97,7 @@ func New(name string, mgr manager.Manager, options Options) (Controller, error)
 		Client:   mgr.GetClient(),
 		Recorder: mgr.GetEventRecorderFor(name),
 		MakeQueue: func() workqueue.RateLimitingInterface {
-			return workqueue.NewNamedRateLimitingQueue(workqueue.DefaultControllerRateLimiter(), name)
+			return workqueue.NewNamedRateLimitingQueue(options.RateLimiter, name)
 		},
 		MaxConcurrentReconciles: options.MaxConcurrentReconciles,
 		Name:                    name,

pkg/ratelimiter/doc.go

@@ -0,0 +1,22 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/*
+Package ratelimiter defines rate limiters used by Controllers to limit how frequently requests may be queued.
+
+Typical rate limiters that can be used are implemented in client-go's workqueue package.
+*/
+package ratelimiter

pkg/ratelimiter/ratelimiter.go

@@ -0,0 +1,14 @@
+package ratelimiter
+
+import "time"
+
+// RateLimiter is an identical interface of client-go workqueue RateLimiter.
+type RateLimiter interface {
+	// When gets an item and gets to decide how long that item should wait
+	When(item interface{}) time.Duration
+	// Forget indicates that an item is finished being retried.  Doesn't matter whether its for perm failing
+	// or for success, we'll stop tracking it
+	Forget(item interface{})
+	// NumRequeues returns back how many failures the item has had
+	NumRequeues(item interface{}) int
+}