Feature Route Reflector (#325)

* Add Route Reflector feature

* Update documentation for route reflector

* Gofmt fix

Author: ut0mt8

Documentation/bgp.md

@@ -22,7 +22,7 @@ This model support more than a single AS per cluster to allow AS per rack or AS
 per node models. Nodes in the cluster does not form full node-to-node mesh.
 Users has to explicitly select this mode by specifying `--nodes-full-mesh=false`
 when launching kube-router. In this mode kube-router expects each node is
-configured with an ASN number from the node's API object annoations. Kube-router
+configured with an ASN number from the node's API object annonations. Kube-router
 will use the node's `kube-router.io/node.asn` annotation value as the ASN
 number for the node.
 
@@ -35,6 +35,33 @@ kubectl annotate node <kube-node> "kube-router.io/node.asn=64512"
 Only nodes with in same ASN form full mesh. Two nodes with different ASNs never
 get peered.
 
+### Route-Reflector setup  Without Full Mesh
+
+This model support the common scheme of using Route Reflector Server node to concentrate 
+peering from Client Peer. This has the big advantage of not needing full mesh, and
+scale better. In this mode kube-router expects each node is configured either in 
+Route Reflector server mode or in Route Reflector client mode. This is done 
+with node `kube-router.io/rr.server=ClusterID`, `kube-router.io/rr.client=ClusterId`
+respectively. In this mode each Route Reflector Client will only peer with Route
+Reflector Servers. Each Route Route Reflector Server will peer other Route Reflector
+Server and with Route Reflector Clients enabling reflection.
+
+Users can annotate node objects with the following command:
+
+```
+kubectl annotate node <kube-node> "kube-router.io/rr.server=42"
+```
+
+for Route Reflector server mode, and 
+
+```
+kubectl annotate node <kube-node> "kube-router.io/rr.client=42"
+```
+
+for Route Reflector client mode.
+
+Only nodes with the same ClusterID in client and server mode will peer together.
+
 ## Peering Outside The Cluster
 ### Global External BGP Peers
 

app/controllers/network_routes_controller.go

@@ -63,6 +63,9 @@ type NetworkRoutingController struct {
 	peerMultihopTtl      uint8
 	MetricsEnabled       bool
 	bgpServerStarted     bool
+	bgpRRClient          bool
+	bgpRRServer          bool
+	bgpClusterId         uint32
 }
 
 var (
@@ -616,6 +619,11 @@ func (nrc *NetworkRoutingController) AdvertiseClusterIp(clusterIp string) error
 // advertises cluster IP's ONLY to the external BGP peers (and not to iBGP peers).
 func (nrc *NetworkRoutingController) addExportPolicies() error {
 
+	// we are rr server do not add export policies
+	if nrc.bgpRRServer {
+		return nil
+	}
+
 	cidr, err := utils.GetPodCidrFromNodeSpec(nrc.clientset, nrc.hostnameOverride)
 	if err != nil {
 		return err
@@ -1005,6 +1013,13 @@ func (nrc *NetworkRoutingController) syncInternalPeers() {
 			continue
 		}
 
+		// we are rr-client peer only with rr-server
+		if nrc.bgpRRClient {
+			if _, ok := node.ObjectMeta.Annotations["kube-router.io/rr.server"]; !ok {
+				continue
+			}
+		}
+
 		// if node full mesh is not requested then just peer with nodes with same ASN
 		// (run iBGP among same ASN peers)
 		if !nrc.bgpFullMeshMode {
@@ -1064,6 +1079,23 @@ func (nrc *NetworkRoutingController) syncInternalPeers() {
 			}
 		}
 
+		// we are rr-server peer with other rr-client with reflection enabled
+		if nrc.bgpRRServer {
+			if _, ok := node.ObjectMeta.Annotations["kube-router.io/rr.client"]; ok {
+				//add rr options with clusterId
+				n.RouteReflector = config.RouteReflector{
+					Config: config.RouteReflectorConfig{
+						RouteReflectorClient:    true,
+						RouteReflectorClusterId: config.RrClusterIdType(nrc.bgpClusterId),
+					},
+					State: config.RouteReflectorState{
+						RouteReflectorClient:    true,
+						RouteReflectorClusterId: config.RrClusterIdType(nrc.bgpClusterId),
+					},
+				}
+			}
+		}
+
 		// TODO: check if a node is alredy added as nieighbour in a better way than add and catch error
 		if err := nrc.bgpServer.AddNeighbor(n); err != nil {
 			if !strings.Contains(err.Error(), "Can't overwrite the existing peer") {
@@ -1271,6 +1303,24 @@ func (nrc *NetworkRoutingController) startBgpServer() error {
 		nrc.nodeAsnNumber = nodeAsnNumber
 	}
 
+	if clusterid, ok := node.ObjectMeta.Annotations["kube-router.io/rr.server"]; ok {
+		glog.Infof("Found rr.server for the node to be %s from the node annotation", clusterid)
+		clusterId, err := strconv.ParseUint(clusterid, 0, 32)
+		if err != nil {
+			return errors.New("Failed to parse rr.server clusterId number specified for the the node")
+		}
+		nrc.bgpClusterId = uint32(clusterId)
+		nrc.bgpRRServer = true
+	} else if clusterid, ok := node.ObjectMeta.Annotations["kube-router.io/rr.client"]; ok {
+		glog.Infof("Found rr.client for the node to be %s from the node annotation", clusterid)
+		clusterId, err := strconv.ParseUint(clusterid, 0, 32)
+		if err != nil {
+			return errors.New("Failed to parse rr.client clusterId number specified for the the node")
+		}
+		nrc.bgpClusterId = uint32(clusterId)
+		nrc.bgpRRClient = true
+	}
+
 	nrc.bgpServer = gobgp.NewBgpServer()
 	go nrc.bgpServer.Serve()
 
@@ -1448,6 +1498,8 @@ func NewNetworkRoutingController(clientset *kubernetes.Clientset,
 	nrc.syncPeriod = kubeRouterConfig.RoutesSyncPeriod
 	nrc.clientset = clientset
 	nrc.activeNodes = make(map[string]bool)
+	nrc.bgpRRClient = false
+	nrc.bgpRRServer = false
 	nrc.bgpServerStarted = false
 
 	nrc.ipSetHandler, err = utils.NewIPSet()