Merge pull request #2203 from justinsb/dnscontroller_fixes

dns-controller: skip over duplicate records

dns-controller/cmd/dns-controller/main.go

@@ -43,6 +43,9 @@ var (
 func main() {
 	fmt.Printf("dns-controller version %s\n", BuildVersion)
 
+	// Be sure to get the glog flags
+	glog.Flush()
+
 	dnsProviderId := "aws-route53"
 	flags.StringVar(&dnsProviderId, "dns", dnsProviderId, "DNS provider we should use (aws-route53, google-clouddns)")
 
@@ -57,6 +60,8 @@ func main() {
 
 	flag.Set("logtostderr", "true")
 
+	flags.AddGoFlagSet(flag.CommandLine)
+
 	flags.Parse(os.Args)
 
 	zoneRules, err := dns.ParseZoneRules(zones)

dns-controller/pkg/dns/dnscontroller.go

@@ -256,7 +256,24 @@ func (c *DNSController) runOnce() error {
 
 		glog.V(4).Infof("updating records for %s: %v -> %v", k, oldValues, newValues)
 
-		err := op.updateRecords(k, newValues, int64(ttl.Seconds()))
+		// Duplicate records are a hard-error on e.g. Route53
+		var dedup []string
+		for _, s := range newValues {
+			alreadyExists := false
+			for _, e := range dedup {
+				if e == s {
+					alreadyExists = true
+					break
+				}
+			}
+			if alreadyExists {
+				glog.V(2).Infof("skipping duplicate record %s", s)
+				continue
+			}
+			dedup = append(dedup, s)
+		}
+
+		err := op.updateRecords(k, dedup, int64(ttl.Seconds()))
 		if err != nil {
 			glog.Infof("error updating records for %s: %v", k, err)
 			errors = append(errors, err)