diff --git a/pkg/kubelet/config/sources.go b/pkg/kubelet/config/sources.go
new file mode 100644
index 00000000000..e26b9de28a4
--- /dev/null
+++ b/pkg/kubelet/config/sources.go
@@ -0,0 +1,67 @@
+/*
+Copyright 2016 The Kubernetes Authors All rights reserved.
+
+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 config implements the pod configuration readers.
+package config
+
+import (
+	"sync"
+
+	"k8s.io/kubernetes/pkg/util/sets"
+)
+
+// SourcesReadyFn is function that returns true if the specified sources have been seen.
+type SourcesReadyFn func(sourcesSeen sets.String) bool
+
+// SourcesReady tracks the set of configured sources seen by the kubelet.
+type SourcesReady interface {
+	// AddSource adds the specified source to the set of sources managed.
+	AddSource(source string)
+	// AllReady returns true if the currently configured sources have all been seen.
+	AllReady() bool
+}
+
+// NewSourcesReady returns a SourcesReady with the specified function.
+func NewSourcesReady(sourcesReadyFn SourcesReadyFn) SourcesReady {
+	return &sourcesImpl{
+		sourcesSeen:    sets.NewString(),
+		sourcesReadyFn: sourcesReadyFn,
+	}
+}
+
+// sourcesImpl implements SourcesReady.  It is thread-safe.
+type sourcesImpl struct {
+	// lock protects access to sources seen.
+	lock sync.RWMutex
+	// set of sources seen.
+	sourcesSeen sets.String
+	// sourcesReady is a function that evaluates if the sources are ready.
+	sourcesReadyFn SourcesReadyFn
+}
+
+// Add adds the specified source to the set of sources managed.
+func (s *sourcesImpl) AddSource(source string) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+	s.sourcesSeen.Insert(source)
+}
+
+// AllReady returns true if each configured source is ready.
+func (s *sourcesImpl) AllReady() bool {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+	return s.sourcesReadyFn(s.sourcesSeen)
+}
diff --git a/pkg/kubelet/kubelet.go b/pkg/kubelet/kubelet.go
index 39687d1d1c7..e6a7fea5d54 100644
--- a/pkg/kubelet/kubelet.go
+++ b/pkg/kubelet/kubelet.go
@@ -50,6 +50,7 @@ import (
 	"k8s.io/kubernetes/pkg/fields"
 	"k8s.io/kubernetes/pkg/kubelet/cadvisor"
 	"k8s.io/kubernetes/pkg/kubelet/cm"
+	"k8s.io/kubernetes/pkg/kubelet/config"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	"k8s.io/kubernetes/pkg/kubelet/dockertools"
 	"k8s.io/kubernetes/pkg/kubelet/envvars"
@@ -157,12 +158,10 @@ type SyncHandler interface {
 	HandlePodCleanups() error
 }
 
-type SourcesReadyFn func(sourcesSeen sets.String) bool
-
 // Option is a functional option type for Kubelet
 type Option func(*Kubelet)
 
-// New instantiates a new Kubelet object along with all the required internal modules.
+// NewMainKubelet instantiates a new Kubelet object along with all the required internal modules.
 // No initialization of Kubelet and its modules should happen here.
 func NewMainKubelet(
 	hostname string,
@@ -177,7 +176,7 @@ func NewMainKubelet(
 	eventQPS float32,
 	eventBurst int,
 	containerGCPolicy kubecontainer.ContainerGCPolicy,
-	sourcesReady SourcesReadyFn,
+	sourcesReadyFn config.SourcesReadyFn,
 	registerNode bool,
 	registerSchedulable bool,
 	standaloneMode bool,
@@ -306,7 +305,7 @@ func NewMainKubelet(
 		resyncInterval:                 resyncInterval,
 		containerRefManager:            containerRefManager,
 		httpClient:                     &http.Client{},
-		sourcesReady:                   sourcesReady,
+		sourcesReady:                   config.NewSourcesReady(sourcesReadyFn),
 		registerNode:                   registerNode,
 		registerSchedulable:            registerSchedulable,
 		standaloneMode:                 standaloneMode,
@@ -490,7 +489,6 @@ func NewMainKubelet(
 
 	klet.backOff = flowcontrol.NewBackOff(backOffPeriod, MaxContainerBackOff)
 	klet.podKillingCh = make(chan *kubecontainer.PodPair, podKillingChannelCapacity)
-	klet.sourcesSeen = sets.NewString()
 	klet.setNodeStatusFuncs = klet.defaultNodeStatusFuncs()
 
 	// apply functional Option's
@@ -558,12 +556,8 @@ type Kubelet struct {
 	// pods on this node.
 	resyncInterval time.Duration
 
-	// sourcesReady is a function to call to determine if all config sources
-	// are ready.
-	sourcesReady SourcesReadyFn
-	// sourcesSeen records the sources seen by kubelet. This set is not thread
-	// safe and should only be access by the main kubelet syncloop goroutine.
-	sourcesSeen sets.String
+	// sourcesReady records the sources seen by the kubelet, it is thread-safe.
+	sourcesReady config.SourcesReady
 
 	// podManager is a facade that abstracts away the various sources of pods
 	// this Kubelet services.
@@ -828,18 +822,6 @@ func (kl *Kubelet) validateNodeIP() error {
 	return fmt.Errorf("Node IP: %q not found in the host's network interfaces", kl.nodeIP.String())
 }
 
-// allSourcesReady returns whether all seen pod sources are ready.
-func (kl *Kubelet) allSourcesReady() bool {
-	// Make a copy of the sourcesSeen list because it's not thread-safe.
-	return kl.sourcesReady(sets.NewString(kl.sourcesSeen.List()...))
-}
-
-// addSource adds a new pod source to the list of sources seen.
-// TODO: reassess in the context of kubernetes/24810
-func (kl *Kubelet) addSource(source string) {
-	kl.sourcesSeen.Insert(source)
-}
-
 // dirExists returns true if the path exists and represents a directory.
 func dirExists(path string) bool {
 	s, err := os.Stat(path)
@@ -2149,7 +2131,7 @@ func (kl *Kubelet) deletePod(pod *api.Pod) error {
 	if pod == nil {
 		return fmt.Errorf("deletePod does not allow nil pod")
 	}
-	if !kl.allSourcesReady() {
+	if !kl.sourcesReady.AllReady() {
 		// If the sources aren't ready, skip deletion, as we may accidentally delete pods
 		// for sources that haven't reported yet.
 		return fmt.Errorf("skipping delete because sources aren't ready yet")
@@ -2496,7 +2478,7 @@ func (kl *Kubelet) syncLoopIteration(configCh <-chan kubetypes.PodUpdate, handle
 			glog.Errorf("Update channel is closed. Exiting the sync loop.")
 			return false
 		}
-		kl.addSource(u.Source)
+		kl.sourcesReady.AddSource(u.Source)
 
 		switch u.Op {
 		case kubetypes.ADD:
@@ -2553,8 +2535,7 @@ func (kl *Kubelet) syncLoopIteration(configCh <-chan kubetypes.PodUpdate, handle
 			handler.HandlePodSyncs([]*api.Pod{pod})
 		}
 	case <-housekeepingCh:
-		// It's time to do housekeeping
-		if !kl.allSourcesReady() {
+		if !kl.sourcesReady.AllReady() {
 			// If the sources aren't ready, skip housekeeping, as we may
 			// accidentally delete pods from unready sources.
 			glog.V(4).Infof("SyncLoop (housekeeping, skipped): sources aren't ready yet.")
diff --git a/pkg/kubelet/kubelet_test.go b/pkg/kubelet/kubelet_test.go
index fe707862ca4..453e2be4624 100644
--- a/pkg/kubelet/kubelet_test.go
+++ b/pkg/kubelet/kubelet_test.go
@@ -43,6 +43,7 @@ import (
 	"k8s.io/kubernetes/pkg/client/testing/core"
 	cadvisortest "k8s.io/kubernetes/pkg/kubelet/cadvisor/testing"
 	"k8s.io/kubernetes/pkg/kubelet/cm"
+	"k8s.io/kubernetes/pkg/kubelet/config"
 	kubecontainer "k8s.io/kubernetes/pkg/kubelet/container"
 	containertest "k8s.io/kubernetes/pkg/kubelet/container/testing"
 	"k8s.io/kubernetes/pkg/kubelet/lifecycle"
@@ -136,7 +137,7 @@ func newTestKubelet(t *testing.T) *TestKubelet {
 	if err := os.MkdirAll(kubelet.rootDirectory, 0750); err != nil {
 		t.Fatalf("can't mkdir(%q): %v", kubelet.rootDirectory, err)
 	}
-	kubelet.sourcesReady = func(_ sets.String) bool { return true }
+	kubelet.sourcesReady = config.NewSourcesReady(func(_ sets.String) bool { return true })
 	kubelet.masterServiceNamespace = api.NamespaceDefault
 	kubelet.serviceLister = testServiceLister{}
 	kubelet.nodeLister = testNodeLister{}
@@ -309,7 +310,7 @@ func TestSyncPodsDeletesWhenSourcesAreReady(t *testing.T) {
 	testKubelet.fakeCadvisor.On("DockerImagesFsInfo").Return(cadvisorapiv2.FsInfo{}, nil)
 	testKubelet.fakeCadvisor.On("RootFsInfo").Return(cadvisorapiv2.FsInfo{}, nil)
 	kubelet := testKubelet.kubelet
-	kubelet.sourcesReady = func(_ sets.String) bool { return ready }
+	kubelet.sourcesReady = config.NewSourcesReady(func(_ sets.String) bool { return ready })
 
 	fakeRuntime.PodList = []*kubecontainer.Pod{
 		{