Support for advertising service external IP to be configured BGP peers (#203)

introduces new flag `--advertise-external-ip`

Fixes #161

Author: murali-reddy

Documentation/README.md

@@ -97,7 +97,8 @@ Also you can choose to run kube-router as agent running on each cluster node. Al
 
 ```
 Usage of ./kube-router:
-      --advertise-cluster-ip                Add Cluster IP to the RIB and advertise to peers.
+      --advertise-cluster-ip                Add Cluster IP of the service to the RIB so that it gets advertises to the BGP peers.
+      --advertise-external-ip               Add External IP of service to the RIB so that it gets advertised to the BGP peers.
       --cleanup-config                      Cleanup iptables rules, ipvs, ipset configuration and exit.
       --cluster-asn uint                    ASN number under which cluster nodes will run iBGP.
       --cluster-cidr string                 CIDR range of pods in the cluster. It is used to identify traffic originating from and destinated to pods.

app/controllers/network_routes_controller.go

@@ -47,6 +47,7 @@ type NetworkRoutingController struct {
 	enablePodEgress      bool
 	hostnameOverride     string
 	advertiseClusterIp   bool
+	advertiseExternalIp  bool
 	defaultNodeAsnNumber uint32
 	nodeAsnNumber        uint32
 	globalPeerRouters    []*config.NeighborConfig
@@ -207,7 +208,7 @@ func (nrc *NetworkRoutingController) Run(stopCh <-chan struct{}, wg *sync.WaitGr
 
 		// advertise cluster IP for the service to be reachable via host
 		if nrc.advertiseClusterIp {
-			glog.Infof("Advertising cluster ips")
+			glog.Infof("Advertising cluster ips of services to the external BGP peers")
 			for _, svc := range watchers.ServiceWatcher.List() {
 				if svc.Spec.Type == "ClusterIP" || svc.Spec.Type == "NodePort" || svc.Spec.Type == "LoadBalancer" {
 
@@ -222,6 +223,22 @@ func (nrc *NetworkRoutingController) Run(stopCh <-chan struct{}, wg *sync.WaitGr
 			}
 		}
 
+		// advertise cluster IP for the service to be reachable via host
+		if nrc.advertiseExternalIp {
+			glog.Infof("Advertising external ips of the services to the external BGP peers")
+			for _, svc := range watchers.ServiceWatcher.List() {
+				if svc.Spec.Type == "ClusterIP" || svc.Spec.Type == "NodePort" {
+					// skip headless services
+					if svc.Spec.ClusterIP == "None" || svc.Spec.ClusterIP == "" {
+						continue
+					}
+					for _, externalIP := range svc.Spec.ExternalIPs {
+						nrc.AdvertiseClusterIp(externalIP)
+					}
+				}
+			}
+		}
+
 		glog.Infof("Performing periodic syn of the routes")
 		err = nrc.advertiseRoute()
 		if err != nil {
@@ -370,6 +387,21 @@ func (nrc *NetworkRoutingController) getClusterIps() ([]string, error) {
 	return clusterIpList, nil
 }
 
+func (nrc *NetworkRoutingController) getExternalIps() ([]string, error) {
+	externalIpList := make([]string, 0)
+	for _, svc := range watchers.ServiceWatcher.List() {
+		if svc.Spec.Type == "ClusterIP" || svc.Spec.Type == "NodePort" {
+
+			// skip headless services
+			if svc.Spec.ClusterIP == "None" || svc.Spec.ClusterIP == "" {
+				continue
+			}
+			externalIpList = append(externalIpList, svc.Spec.ExternalIPs...)
+		}
+	}
+	return externalIpList, nil
+}
+
 // Used for processing Annotations that may contain multiple items
 // Pass this the string and the delimiter
 func stringToSlice(s, d string) []string {
@@ -525,6 +557,10 @@ func (nrc *NetworkRoutingController) addExportPolicies() error {
 	for _, ip := range clusterIps {
 		clusterIpPrefixList = append(clusterIpPrefixList, config.Prefix{IpPrefix: ip + "/32"})
 	}
+	externalIps, _ := nrc.getExternalIps()
+	for _, ip := range externalIps {
+		clusterIpPrefixList = append(clusterIpPrefixList, config.Prefix{IpPrefix: ip + "/32"})
+	}
 	clusterIpPrefixSet, err := table.NewPrefixSet(config.PrefixSet{
 		PrefixSetName: "clusteripprefixset",
 		PrefixList:    clusterIpPrefixList,
@@ -1307,6 +1343,7 @@ func NewNetworkRoutingController(clientset *kubernetes.Clientset,
 	}
 
 	nrc.advertiseClusterIp = kubeRouterConfig.AdvertiseClusterIp
+	nrc.advertiseExternalIp = kubeRouterConfig.AdvertiseExternalIp
 
 	nrc.enableOverlays = kubeRouterConfig.EnableOverlay
 

app/options/options.go

@@ -24,6 +24,7 @@ type KubeRouterConfig struct {
 	EnablePodEgress     bool
 	HostnameOverride    string
 	AdvertiseClusterIp  bool
+	AdvertiseExternalIp bool
 	PeerRouters         []net.IP
 	PeerASNs            []uint
 	ClusterAsn          uint
@@ -74,7 +75,9 @@ func (s *KubeRouterConfig) AddFlags(fs *pflag.FlagSet) {
 	fs.DurationVar(&s.RoutesSyncPeriod, "routes-sync-period", s.RoutesSyncPeriod,
 		"The delay between route updates and advertisements (e.g. '5s', '1m', '2h22m'). Must be greater than 0.")
 	fs.BoolVar(&s.AdvertiseClusterIp, "advertise-cluster-ip", false,
-		"Add Cluster IP to the RIB and advertise to peers.")
+		"Add Cluster IP of the service to the RIB so that it gets advertises to the BGP peers.")
+	fs.BoolVar(&s.AdvertiseExternalIp, "advertise-external-ip", false,
+		"Add External IP of service to the RIB so that it gets advertised to the BGP peers.")
 	fs.IPSliceVar(&s.PeerRouters, "peer-router-ips", s.PeerRouters,
 		"The ip address of the external router to which all nodes will peer and advertise the cluster ip and pod cidr's.")
 	fs.UintVar(&s.ClusterAsn, "cluster-asn", s.ClusterAsn,