Fix NPE when performing cleanup() (#458)

* Fix NPE when performing cleanup()

* update cleanup documentaion

Author: murali-reddy

docs/user-guide.md

@@ -95,9 +95,10 @@ kube-router --master=http://192.168.1.99:8080/ --run-firewall=true --run-service
 
 ## cleanup configuration
 
-You can clean up all the configurations done (to ipvs, iptables, ip routes) by kube-router on the node by running
+Please delete kube-router daemonset and then clean up all the configurations done (to ipvs, iptables, ipset, ip routes etc) by kube-router on the node by running below command.
+
 ```
- kube-router --cleanup-config
+docker run --privileged --net=host cloudnativelabs/kube-router --cleanup-config
 ```
 
 ## trying kube-router as alternative to kube-proxy

pkg/controllers/netpol/network_policy_controller.go

@@ -1414,7 +1414,15 @@ func (npc *NetworkPolicyController) Cleanup() {
 	}
 
 	// delete all ipsets
-	err = npc.ipSetHandler.DestroyAllWithin()
+	ipset, err := utils.NewIPSet()
+	if err != nil {
+		glog.Errorf("Failed to clean up ipsets: " + err.Error())
+	}
+	err = ipset.Save()
+	if err != nil {
+		glog.Errorf("Failed to clean up ipsets: " + err.Error())
+	}
+	err = ipset.DestroyAllWithin()
 	if err != nil {
 		glog.Errorf("Failed to clean up ipsets: " + err.Error())
 	}

pkg/controllers/routing/network_routes_controller.go

@@ -446,7 +446,16 @@ func (nrc *NetworkRoutingController) Cleanup() {
 		glog.Warningf("Error deleting Pod egress iptable rule: %s", err.Error())
 	}
 
-	err = nrc.ipSetHandler.DestroyAllWithin()
+	// delete all ipsets created by kube-router
+	ipset, err := utils.NewIPSet()
+	if err != nil {
+		glog.Errorf("Failed to clean up ipsets: " + err.Error())
+	}
+	err = ipset.Save()
+	if err != nil {
+		glog.Errorf("Failed to clean up ipsets: " + err.Error())
+	}
+	err = ipset.DestroyAllWithin()
 	if err != nil {
 		glog.Warningf("Error deleting ipset: %s", err.Error())
 	}