feat(lb): honor lb vip mask from api

pkg/kloudlb/speaker/speaker.go

@@ -5,11 +5,12 @@ import (
 	"fmt"
 	"net"
 	"os"
+	"strings"
 	"sync"
 	"time"
 
-	corev1 "k8s.io/api/core/v1"
 	coordinationv1 "k8s.io/api/coordination/v1"
+	corev1 "k8s.io/api/core/v1"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/util/wait"
@@ -141,26 +142,31 @@ func (s *Speaker) sync(ctx context.Context, key string) error {
 		return err
 	}
 
-	ip := serviceExternalIP(svc)
-	if ip == "" || svc.DeletionTimestamp != nil {
-		s.stopLeading(key, ip)
+	vip := serviceExternalVIP(svc)
+	if vip == "" || svc.DeletionTimestamp != nil {
+		s.stopLeading(key, vip)
 		return nil
 	}
 
 	leaseName := leaseNameFor(key)
-	leader, err := s.acquireLease(ctx, leaseName, ip)
+	leader, err := s.acquireLease(ctx, leaseName, vip)
 	if err != nil {
 		return err
 	}
 	if leader != s.nodeName {
-		s.stopLeading(key, ip)
+		s.stopLeading(key, vip)
 		return nil
 	}
 
-	return s.ensureVIP(ip)
+	return s.ensureVIP(vip)
 }
 
-func serviceExternalIP(svc *corev1.Service) string {
+func serviceExternalVIP(svc *corev1.Service) string {
+	if svc.Annotations != nil {
+		if vip := strings.TrimSpace(svc.Annotations[kloudlb.AnnotationVIP]); vip != "" {
+			return vip
+		}
+	}
 	for _, ing := range svc.Status.LoadBalancer.Ingress {
 		if ing.IP != "" {
 			return ing.IP
@@ -287,17 +293,15 @@ func addVIP(ifaceName, ip string) error {
 	if err != nil {
 		return fmt.Errorf("lookup interface %s: %w", ifaceName, err)
 	}
-	parsed := net.ParseIP(ip)
-	if parsed == nil {
-		return fmt.Errorf("invalid vip %q", ip)
-	}
-	addr := &netlink.Addr{
-		IPNet: &net.IPNet{IP: parsed.To4(), Mask: net.CIDRMask(32, 32)},
+	ipNet, err := vipToIPNet(link, ip)
+	if err != nil {
+		return err
 	}
+	addr := &netlink.Addr{IPNet: ipNet}
 	if err := netlink.AddrAdd(link, addr); err != nil {
 		return fmt.Errorf("add vip %s on %s: %w", ip, ifaceName, err)
 	}
-	return sendGratuitousARP(link, parsed.To4())
+	return sendGratuitousARP(link, ipNet.IP.To4())
 }
 
 func removeVIP(ifaceName, ip string) error {
@@ -305,16 +309,63 @@ func removeVIP(ifaceName, ip string) error {
 	if err != nil {
 		return err
 	}
-	parsed := net.ParseIP(ip)
-	if parsed == nil {
-		return fmt.Errorf("invalid vip %q", ip)
-	}
-	addr := &netlink.Addr{
-		IPNet: &net.IPNet{IP: parsed.To4(), Mask: net.CIDRMask(32, 32)},
+	ipNet, err := vipToIPNet(link, ip)
+	if err != nil {
+		return err
 	}
+	addr := &netlink.Addr{IPNet: ipNet}
 	return netlink.AddrDel(link, addr)
 }
 
+func vipToIPNet(link netlink.Link, vip string) (*net.IPNet, error) {
+	vip = strings.TrimSpace(vip)
+	if vip == "" {
+		return nil, fmt.Errorf("vip is required")
+	}
+	if strings.Contains(vip, "/") {
+		ip, ipNet, err := net.ParseCIDR(vip)
+		if err != nil {
+			return nil, fmt.Errorf("invalid vip %q: %w", vip, err)
+		}
+		ipv4 := ip.To4()
+		if ipv4 == nil {
+			return nil, fmt.Errorf("vip %q is not ipv4", vip)
+		}
+		return &net.IPNet{IP: ipv4, Mask: ipNet.Mask}, nil
+	}
+
+	ip := net.ParseIP(vip)
+	if ip == nil || ip.To4() == nil {
+		return nil, fmt.Errorf("invalid vip %q", vip)
+	}
+	mask, err := interfaceIPv4Mask(link)
+	if err != nil {
+		return nil, err
+	}
+	return &net.IPNet{IP: ip.To4(), Mask: mask}, nil
+}
+
+func interfaceIPv4Mask(link netlink.Link) (net.IPMask, error) {
+	addrs, err := netlink.AddrList(link, 0)
+	if err != nil {
+		return nil, fmt.Errorf("list ipv4 addresses on %s: %w", link.Attrs().Name, err)
+	}
+	for _, addr := range addrs {
+		if addr.IPNet == nil || addr.IPNet.IP == nil || addr.IPNet.Mask == nil {
+			continue
+		}
+		ip := addr.IPNet.IP.To4()
+		if ip == nil {
+			continue
+		}
+		if !ip.IsGlobalUnicast() {
+			continue
+		}
+		return addr.IPNet.Mask, nil
+	}
+	return nil, fmt.Errorf("cannot infer ipv4 mask from interface %s", link.Attrs().Name)
+}
+
 func sendGratuitousARP(link netlink.Link, ip net.IP) error {
 	if ip == nil {
 		return fmt.Errorf("ip is required")