routing: gracefully handle missing node IP during BGP announcements

calico-vpp-agent/common/common.go

@@ -212,6 +212,19 @@ func FullyQualified(addr net.IP) *net.IPNet {
 	}
 }
 
+var (
+	ErrNoNodeIPv4 = errors.New("no ip4 address for node")
+	ErrNoNodeIPv6 = errors.New("no ip6 address for node")
+)
+
+func IsMissingNodeIP(err error) bool {
+	if err == nil {
+		return false
+	}
+	cause := errors.Cause(err)
+	return cause == ErrNoNodeIPv4 || cause == ErrNoNodeIPv6
+}
+
 const (
 	aggregatedPrefixSetBaseName = "aggregated"
 	hostPrefixSetBaseName       = "host"
@@ -289,7 +302,7 @@ func MakePath(prefix string, isWithdrawal bool, nodeIPv4 *net.IP, nodeIPv6 *net.
 
 	if ipNet.IP.To4() != nil {
 		if nodeIPv4 == nil {
-			return nil, fmt.Errorf("no ip4 address for node")
+			return nil, ErrNoNodeIPv4
 		}
 		family = &BgpFamilyUnicastIPv4
 		if vni != 0 {
@@ -298,6 +311,9 @@ func MakePath(prefix string, isWithdrawal bool, nodeIPv4 *net.IP, nodeIPv6 *net.
 		var nhAttr *apb.Any
 
 		if *config.GetCalicoVppFeatureGates().SRv6Enabled {
+			if nodeIPv6 == nil {
+				return nil, ErrNoNodeIPv6
+			}
 			nhAttr, err = apb.New(&bgpapi.NextHopAttribute{
 				NextHop: nodeIPv6.String(),
 			})
@@ -312,7 +328,7 @@ func MakePath(prefix string, isWithdrawal bool, nodeIPv4 *net.IP, nodeIPv6 *net.
 		attrs = append(attrs, nhAttr)
 	} else {
 		if nodeIPv6 == nil {
-			return nil, fmt.Errorf("no ip6 address for node")
+			return nil, ErrNoNodeIPv6
 		}
 		family = &BgpFamilyUnicastIPv6
 		if vni != 0 {

calico-vpp-agent/routing/routing_server.go

@@ -258,6 +258,11 @@ func (s *Server) announceLocalAddress(addr *net.IPNet, vni uint32) error {
 	nodeIP4, nodeIP6 := common.GetBGPSpecAddresses(s.nodeBGPSpec)
 	path, err := common.MakePath(addr.String(), false /* isWithdrawal */, nodeIP4, nodeIP6, vni, uint32(*s.BGPConf.ASNumber))
 	if err != nil {
+		if common.IsMissingNodeIP(err) {
+			s.log.WithError(err).Warnf("Skipping BGP announce for %s: node IP missing", addr.String())
+			s.localAddressMap[addr.String()] = localAddress{ipNet: addr, vni: vni}
+			return nil
+		}
 		return errors.Wrap(err, "error making path to announce")
 	}
 	s.localAddressMap[addr.String()] = localAddress{ipNet: addr, vni: vni}
@@ -273,6 +278,11 @@ func (s *Server) withdrawLocalAddress(addr *net.IPNet, vni uint32) error {
 	nodeIP4, nodeIP6 := common.GetBGPSpecAddresses(s.nodeBGPSpec)
 	path, err := common.MakePath(addr.String(), true /* isWithdrawal */, nodeIP4, nodeIP6, vni, uint32(*s.BGPConf.ASNumber))
 	if err != nil {
+		if common.IsMissingNodeIP(err) {
+			s.log.WithError(err).Warnf("Skipping BGP withdraw for %s: node IP missing", addr.String())
+			delete(s.localAddressMap, addr.String())
+			return nil
+		}
 		return errors.Wrap(err, "error making path to withdraw")
 	}
 	delete(s.localAddressMap, addr.String())

calico-vpp-agent/watchers/prefix_watcher.go

@@ -74,6 +74,10 @@ func (w *PrefixWatcher) WatchPrefix(t *tomb.Tomb) error {
 				ip4, ip6 := common.GetBGPSpecAddresses(w.nodeBGPSpec)
 				path, err := common.MakePath(prefix, false /* isWithdrawal */, ip4, ip6, 0, 0)
 				if err != nil {
+					if common.IsMissingNodeIP(err) {
+						w.log.WithError(err).Warnf("Skipping prefix announcement for %s: node IP missing", prefix)
+						continue
+					}
 					return errors.Wrap(err, "error making new path for assigned prefix")
 				}
 				toAdd = append(toAdd, path)
@@ -90,6 +94,10 @@ func (w *PrefixWatcher) WatchPrefix(t *tomb.Tomb) error {
 				ip4, ip6 := common.GetBGPSpecAddresses(w.nodeBGPSpec)
 				path, err := common.MakePath(p, true /* isWithdrawal */, ip4, ip6, 0, 0)
 				if err != nil {
+					if common.IsMissingNodeIP(err) {
+						w.log.WithError(err).Warnf("Skipping prefix withdrawal for %s: node IP missing", p)
+						continue
+					}
 					return errors.Wrap(err, "error making new path for removed prefix")
 				}
 				toRemove = append(toRemove, path)