Reclaim IPs when node name is re-used

If we can see that a different peer was previously running with the
same node name, mark it for reclaim.

prog/kube-utils/main.go

@@ -96,7 +96,7 @@ func checkIamInPeerList(cml *configMapAnnotations, c *kubernetes.Clientset, peer
 
 // For each of those peers that is no longer listed as a node by
 // Kubernetes, remove it from Weave IPAM
-func reclaimRemovedPeers(weave *weaveapi.Client, cml *configMapAnnotations, nodes []nodeInfo, myPeerName string) error {
+func reclaimRemovedPeers(weave *weaveapi.Client, cml *configMapAnnotations, nodes []nodeInfo, myPeerName, myNodeName string) error {
 	for loopsWhenNothingChanged := 0; loopsWhenNothingChanged < 3; loopsWhenNothingChanged++ {
 		if err := cml.Init(); err != nil {
 			return err
@@ -110,9 +110,19 @@ func reclaimRemovedPeers(weave *weaveapi.Client, cml *configMapAnnotations, node
 		for _, peer := range storedPeerList.Peers {
 			peerMap[peer.NodeName] = peer
 		}
+		// 1a. Check if the list held a peer with my NodeName but different PeerName
+		var deleteOldMe *peerInfo
+		if oldMe, found := peerMap[myNodeName]; found && oldMe.PeerName != myPeerName {
+			common.Log.Infof("[kube-peers] old peer found with node name %s and peer name %s", oldMe.NodeName, oldMe.PeerName)
+			deleteOldMe = &oldMe
+		}
+		// Now delete the entries in the map that are current nodes
 		for _, node := range nodes {
 			delete(peerMap, node.name)
 		}
+		if deleteOldMe != nil {
+			peerMap[deleteOldMe.NodeName] = *deleteOldMe
+		}
 		common.Log.Debugln("[kube-peers] Nodes that have disappeared:", peerMap)
 		if len(peerMap) == 0 {
 			break
@@ -239,7 +249,7 @@ func main() {
 		common.Log.Infoln("[kube-peers] Added myself to peer list", list)
 
 		weave := weaveapi.NewClient(os.Getenv("WEAVE_HTTP_ADDR"), common.Log)
-		err = reclaimRemovedPeers(weave, cml, peers, peerName)
+		err = reclaimRemovedPeers(weave, cml, peers, peerName, nodeName)
 		if err != nil {
 			common.Log.Fatalf("[kube-peers] Error while reclaiming space: %v", err)
 		}