Add flannel-external-ip when there is a k3s node-external-ip

pkg/agent/flannel/flannel.go

@@ -40,13 +40,19 @@ const (
 	subnetFile = "/run/flannel/subnet.env"
 )
 
+var (
+	FlannelBaseAnnotation         = "flannel.alpha.coreos.com"
+	FlannelExternalIPv4Annotation = FlannelBaseAnnotation + "/public-ip-overwrite"
+	FlannelExternalIPv6Annotation = FlannelBaseAnnotation + "/public-ipv6-overwrite"
+)
+
 func flannel(ctx context.Context, flannelIface *net.Interface, flannelConf, kubeConfigFile string, flannelIPv6Masq bool, netMode int) error {
 	extIface, err := LookupExtInterface(flannelIface, netMode)
 	if err != nil {
 		return err
 	}
 
-	sm, err := kube.NewSubnetManager(ctx, "", kubeConfigFile, "flannel.alpha.coreos.com", flannelConf, false)
+	sm, err := kube.NewSubnetManager(ctx, "", kubeConfigFile, FlannelBaseAnnotation, flannelConf, false)
 	if err != nil {
 		return err
 	}

pkg/agent/run.go

@@ -399,6 +399,7 @@ func updateLegacyAddressLabels(agentConfig *daemonconfig.Agent, nodeLabels map[s
 	return nil, false
 }
 
+// updateAddressAnnotations updates the node annotations with important information about IP addresses of the node
 func updateAddressAnnotations(agentConfig *daemonconfig.Agent, nodeAnnotations map[string]string) (map[string]string, bool) {
 	result := map[string]string{
 		cp.InternalIPKey: util.JoinIPs(agentConfig.NodeIPs),
@@ -407,6 +408,14 @@ func updateAddressAnnotations(agentConfig *daemonconfig.Agent, nodeAnnotations m
 
 	if agentConfig.NodeExternalIP != "" {
 		result[cp.ExternalIPKey] = util.JoinIPs(agentConfig.NodeExternalIPs)
+		for _, ipAddress := range agentConfig.NodeExternalIPs {
+			if utilsnet.IsIPv4(ipAddress) {
+				result[flannel.FlannelExternalIPv4Annotation] = ipAddress.String()
+			}
+			if utilsnet.IsIPv6(ipAddress) {
+				result[flannel.FlannelExternalIPv6Annotation] = ipAddress.String()
+			}
+		}
 	}
 
 	result = labels.Merge(nodeAnnotations, result)