Test for and fix crash with nil client in kubelet.

Added test that fails before fix.
Fixed use of nil pointer.

cmd/kubelet/kubelet.go

@@ -68,6 +68,7 @@ var (
 	clusterDomain           = flag.String("cluster_domain", "", "Domain for this cluster.  If set, kubelet will configure all containers to search this domain in addition to the host's search domains")
 	masterServiceNamespace  = flag.String("master_service_namespace", api.NamespaceDefault, "The namespace from which the kubernetes master services should be injected into pods")
 	clusterDNS              = util.IP(nil)
+	reallyCrashForTesting   = flag.Bool("really_crash_for_testing", false, "If true, crash with panics more often.")
 )
 
 func init() {
@@ -96,6 +97,7 @@ func setupRunOnce() {
 func main() {
 	util.InitFlags()
 	util.InitLogs()
+	util.ReallyCrash = *reallyCrashForTesting
 	defer util.FlushLogs()
 	rand.Seed(time.Now().UTC().UnixNano())
 

hack/test-cmd.sh

@@ -51,9 +51,19 @@ CTLRMGR_PORT=${CTLRMGR_PORT:-10252}
 kube::log::status "Running kubectl with no options"
 "${KUBE_OUTPUT_HOSTBIN}/kubectl"
 
-# Start kubelet
-kube::log::status "Starting kubelet"
+kube::log::status "Starting kubelet in masterless mode"
 "${KUBE_OUTPUT_HOSTBIN}/kubelet" \
+  --really_crash_for_testing=true \
+  --root_dir=/tmp/kubelet.$$ \
+  --address="127.0.0.1" \
+  --port="$KUBELET_PORT" 1>&2 &
+KUBELET_PID=$!
+kube::util::wait_for_url "http://127.0.0.1:${KUBELET_PORT}/healthz" "kubelet: "
+kill ${KUBELET_PID} 1>&2 2>/dev/null
+
+kube::log::status "Starting kubelet in masterful mode"
+"${KUBE_OUTPUT_HOSTBIN}/kubelet" \
+  --really_crash_for_testing=true \
   --root_dir=/tmp/kubelet.$$ \
   --etcd_servers="http://${ETCD_HOST}:${ETCD_PORT}" \
   --hostname_override="127.0.0.1" \

pkg/client/cache/listwatch.go

@@ -24,7 +24,7 @@ import (
 )
 
 // ListWatch knows how to list and watch a set of apiserver resources.  It satisfies the ListerWatcher interface.
-// It is a convenience function for users of NewReflector, etc.
+// It is a convenience function for users of NewReflector, etc.  Client must not be nil.
 type ListWatch struct {
 	Client        *client.Client
 	FieldSelector labels.Selector

pkg/kubelet/kubelet.go

@@ -93,7 +93,9 @@ func NewMainKubelet(
 	}
 
 	serviceStore := cache.NewStore()
-	cache.NewReflector(&cache.ListWatch{kubeClient, labels.Everything(), "services", api.NamespaceAll}, &api.Service{}, serviceStore).Run()
+	if kubeClient != nil {
+		cache.NewReflector(&cache.ListWatch{kubeClient, labels.Everything(), "services", api.NamespaceAll}, &api.Service{}, serviceStore).Run()
+	}
 	serviceLister := &cache.StoreToServiceLister{serviceStore}
 
 	klet := &Kubelet{