Fix issue with coredns node hosts controller

The nodes controller was reading from the configmaps cache, but doesn't add any handlers, so if no other controller added configmap handlers, the cache would remain empty.

Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
(cherry picked from commit 888f866dae)
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>

pkg/node/controller.go

@@ -9,6 +9,7 @@ import (
 	coreclient "github.com/rancher/wrangler/pkg/generated/controllers/core/v1"
 	"github.com/sirupsen/logrus"
 	core "k8s.io/api/core/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
 func Register(ctx context.Context,
@@ -76,13 +77,12 @@ func (h *handler) updateCoreDNSConfigMap(nodeName, nodeAddress string, removed b
 		return nil
 	}
 
-	configMapCache, err := h.configMaps.Cache().Get("kube-system", "coredns")
-	if err != nil || configMapCache == nil {
+	configMap, err := h.configMaps.Get("kube-system", "coredns", metav1.GetOptions{})
+	if err != nil || configMap == nil {
 		logrus.Warn(errors.Wrap(err, "Unable to fetch coredns config map"))
 		return nil
 	}
 
-	configMap := configMapCache.DeepCopy()
 	hosts := configMap.Data["NodeHosts"]
 	hostsMap := map[string]string{}
 
@@ -116,6 +116,10 @@ func (h *handler) updateCoreDNSConfigMap(nodeName, nodeAddress string, removed b
 	for host, ip := range hostsMap {
 		newHosts += ip + " " + host + "\n"
 	}
+
+	if configMap.Data == nil {
+		configMap.Data = map[string]string{}
+	}
 	configMap.Data["NodeHosts"] = newHosts
 
 	if _, err := h.configMaps.Update(configMap); err != nil {