fix(network_routes): missing node ip -> error log (#904)

Before we used to raise an error when a node was missing an IP, but it
turns out that this is not a required attribute of a node. And while it
is rare that a node would be missing an IP address, a node doesn't
require an IP address or a name or really much of anything in order to
exist.

This brings us to stronger conformance with the Kubernetes API and makes
it so that kube-router logs errors rather than changing it's health
status and potentially causing cascading failures across the fleet if a
user adds a node like this.

pkg/controllers/routing/bgp_peers.go

@@ -45,7 +45,11 @@ func (nrc *NetworkRoutingController) syncInternalPeers() {
 	currentNodes := make([]string, 0)
 	for _, obj := range nodes {
 		node := obj.(*v1core.Node)
-		nodeIP, _ := utils.GetNodeIP(node)
+		nodeIP, err := utils.GetNodeIP(node)
+		if err != nil {
+			glog.Errorf("Failed to find a node IP and therefore cannot sync internal BGP Peer: %v", err)
+			continue
+		}
 
 		// skip self
 		if nodeIP.String() == nrc.nodeIP.String() {
@@ -321,7 +325,11 @@ func (nrc *NetworkRoutingController) newNodeEventHandler() cache.ResourceEventHa
 	return cache.ResourceEventHandlerFuncs{
 		AddFunc: func(obj interface{}) {
 			node := obj.(*v1core.Node)
-			nodeIP, _ := utils.GetNodeIP(node)
+			nodeIP, err := utils.GetNodeIP(node)
+			if err != nil {
+				glog.Errorf("New node received, but we were unable to add it as we were couldn't find it's node IP: %v", err)
+				return
+			}
 
 			glog.V(2).Infof("Received node %s added update from watch API so peer with new node", nodeIP)
 			nrc.OnNodeUpdate(obj)
@@ -344,9 +352,15 @@ func (nrc *NetworkRoutingController) newNodeEventHandler() cache.ResourceEventHa
 					return
 				}
 			}
-			nodeIP, _ := utils.GetNodeIP(node)
+			nodeIP, err := utils.GetNodeIP(node)
+			// In this case even if we can't get the NodeIP that's alright as the node is being removed anyway and
+			// future node lister operations that happen in OnNodeUpdate won't be affected as the node won't be returned
+			if err == nil {
+				glog.Infof("Received node %s removed update from watch API, so remove node from peer", nodeIP)
+			} else {
+				glog.Infof("Received node (IP unavailable) removed update from watch API, so remove node from peer")
+			}
 
-			glog.Infof("Received node %s removed update from watch API, so remove node from peer", nodeIP)
 			nrc.OnNodeUpdate(obj)
 		},
 	}

pkg/controllers/routing/bgp_policies.go

@@ -2,7 +2,7 @@ package routing
 
 import (
 	"errors"
-	"fmt"
+	"github.com/golang/glog"
 
 	"github.com/cloudnativelabs/kube-router/pkg/utils"
 	"github.com/osrg/gobgp/config"
@@ -56,7 +56,8 @@ func (nrc *NetworkRoutingController) AddPolicies() error {
 			nodeObj := node.(*v1core.Node)
 			nodeIP, err := utils.GetNodeIP(nodeObj)
 			if err != nil {
-				return fmt.Errorf("Failed to find a node IP: %s", err)
+				glog.Errorf("Failed to find a node IP and therefore cannot add internal BGP Peer: %v", err)
+				continue
 			}
 			iBGPPeers = append(iBGPPeers, nodeIP.String())
 		}

pkg/controllers/routing/network_routes_controller.go

@@ -553,7 +553,8 @@ func (nrc *NetworkRoutingController) syncNodeIPSets() error {
 		currentPodCidrs = append(currentPodCidrs, podCIDR)
 		nodeIP, err := utils.GetNodeIP(node)
 		if err != nil {
-			return fmt.Errorf("Failed to find a node IP: %s", err)
+			glog.Errorf("Failed to find a node IP, cannot add to node ipset which could affect routing: %v", err)
+			continue
 		}
 		currentNodeIPs = append(currentNodeIPs, nodeIP.String())
 	}