Do not remove service record while scaling down

While scaling down, currently we are removing the service record even if
the LB entry for the vip is not fully removed. This causes resolution
issues when scaling down. Fixed it by removing the service record only
if the LB for the vip is going away.

Signed-off-by: Jana Radhakrishnan <mrjana@docker.com>

libnetwork/service_linux.go

@@ -145,22 +145,19 @@ func (c *controller) rmServiceBinding(name, sid, nid, eid string, vip net.IP, in
 		n.(*network).deleteSvcRecords("tasks."+alias, ip, nil, false)
 	}
 
-	// Make sure to remove the right IP since if vip is
-	// not valid we would have added a DNS RR record.
-	svcIP := vip
-	if len(svcIP) == 0 {
-		svcIP = ip
-	}
-	n.(*network).deleteSvcRecords(name, svcIP, nil, false)
-	for _, alias := range aliases {
-		n.(*network).deleteSvcRecords(alias, svcIP, nil, false)
+	// If we are doing DNS RR add the endpoint IP to DNS record
+	// right away.
+	if len(vip) == 0 {
+		n.(*network).deleteSvcRecords(name, ip, nil, false)
+		for _, alias := range aliases {
+			n.(*network).deleteSvcRecords(alias, ip, nil, false)
+		}
 	}
 
 	s.Lock()
-	defer s.Unlock()
-
 	lb, ok := s.loadBalancers[nid]
 	if !ok {
+		s.Unlock()
 		return nil
 	}
 
@@ -185,6 +182,15 @@ func (c *controller) rmServiceBinding(name, sid, nid, eid string, vip net.IP, in
 	if len(vip) != 0 {
 		n.(*network).rmLBBackend(ip, vip, lb.fwMark, ingressPorts, rmService)
 	}
+	s.Unlock()
+
+	// Remove the DNS record for VIP only if we are removing the service
+	if rmService && len(vip) != 0 {
+		n.(*network).deleteSvcRecords(name, vip, nil, false)
+		for _, alias := range aliases {
+			n.(*network).deleteSvcRecords(alias, vip, nil, false)
+		}
+	}
 
 	return nil
 }