cleanup, ensure haproxy is running and disallow writes to followers

pkg/vip/arp_linux.go

@@ -0,0 +1,38 @@
+package vip
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/mdlayher/arp"
+	"github.com/mdlayher/ethernet"
+)
+
+func sendARP(ip net.IP, iface *net.Interface) error {
+	c, err := arp.Dial(iface)
+	if err != nil {
+		return err
+	}
+	for _, op := range []arp.Operation{arp.OperationRequest, arp.OperationReply} {
+		pkt, err := arp.NewPacket(op, iface.HardwareAddr, ip, ethernet.Broadcast, ip)
+		if err != nil {
+			return fmt.Errorf("assembling %q gratuitous packet for %q: %s", op, ip, err)
+		}
+		if err = c.WriteTo(pkt, ethernet.Broadcast); err != nil {
+			return fmt.Errorf("writing %q gratuitous packet for %q: %s", op, ip, err)
+		}
+	}
+	return nil
+}
+
+func ARPSendGratuitous(cidr, iface string) error {
+	i, err := net.InterfaceByName(iface)
+	if err != nil {
+		return fmt.Errorf("failed to get interface %q: %v", iface, err)
+	}
+	ip, _, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return fmt.Errorf("failed to parse cidr: %s", cidr)
+	}
+	return sendARP(ip, i)
+}