feat: add option to use only new format TXT records

Author: malpou

main.go

@@ -387,7 +387,7 @@ func main() {
 	case "noop":
 		r, err = registry.NewNoopRegistry(p)
 	case "txt":
-		r, err = registry.NewTXTRegistry(p, cfg.TXTPrefix, cfg.TXTSuffix, cfg.TXTOwnerID, cfg.TXTCacheInterval, cfg.TXTWildcardReplacement, cfg.ManagedDNSRecordTypes, cfg.ExcludeDNSRecordTypes, cfg.TXTEncryptEnabled, []byte(cfg.TXTEncryptAESKey))
+		r, err = registry.NewTXTRegistry(p, cfg.TXTPrefix, cfg.TXTSuffix, cfg.TXTOwnerID, cfg.TXTCacheInterval, cfg.TXTWildcardReplacement, cfg.ManagedDNSRecordTypes, cfg.ExcludeDNSRecordTypes, cfg.TXTEncryptEnabled, []byte(cfg.TXTEncryptAESKey), cfg.TXTNewFormatOnly)
 	case "aws-sd":
 		r, err = registry.NewAWSSDRegistry(p, cfg.TXTOwnerID)
 	default:

pkg/apis/externaldns/types.go

@@ -138,6 +138,7 @@ type Config struct {
 	TXTSuffix                          string
 	TXTEncryptEnabled                  bool
 	TXTEncryptAESKey                   string `secure:"yes"`
+	TXTNewFormatOnly                   bool
 	Interval                           time.Duration
 	MinEventSyncInterval               time.Duration
 	Once                               bool
@@ -299,6 +300,7 @@ var defaultConfig = &Config{
 	MinEventSyncInterval:        5 * time.Second,
 	TXTEncryptEnabled:           false,
 	TXTEncryptAESKey:            "",
+	TXTNewFormatOnly:            false,
 	Interval:                    time.Minute,
 	Once:                        false,
 	DryRun:                      false,

registry/txt.go

@@ -56,10 +56,19 @@ type TXTRegistry struct {
 	// encrypt text records
 	txtEncryptEnabled bool
 	txtEncryptAESKey  []byte
+
+	newFormatOnly bool
 }
 
-// NewTXTRegistry returns new TXTRegistry object
-func NewTXTRegistry(provider provider.Provider, txtPrefix, txtSuffix, ownerID string, cacheInterval time.Duration, txtWildcardReplacement string, managedRecordTypes, excludeRecordTypes []string, txtEncryptEnabled bool, txtEncryptAESKey []byte) (*TXTRegistry, error) {
+// NewTXTRegistry returns a new TXTRegistry object. When newFormatOnly is true, it will only
+// generate new format TXT records, otherwise it generates both old and new formats for
+// backwards compatibility.
+func NewTXTRegistry(provider provider.Provider, txtPrefix, txtSuffix, ownerID string,
+	cacheInterval time.Duration, txtWildcardReplacement string,
+	managedRecordTypes, excludeRecordTypes []string,
+	txtEncryptEnabled bool, txtEncryptAESKey []byte,
+	newFormatOnly bool) (*TXTRegistry, error) {
+
 	if ownerID == "" {
 		return nil, errors.New("owner id cannot be empty")
 	}
@@ -88,6 +97,7 @@ func NewTXTRegistry(provider provider.Provider, txtPrefix, txtSuffix, ownerID st
 		excludeRecordTypes:  excludeRecordTypes,
 		txtEncryptEnabled:   txtEncryptEnabled,
 		txtEncryptAESKey:    txtEncryptAESKey,
+		newFormatOnly:       newFormatOnly,
 	}, nil
 }
 
@@ -209,12 +219,14 @@ func (im *TXTRegistry) Records(ctx context.Context) ([]*endpoint.Endpoint, error
 	return endpoints, nil
 }
 
-// generateTXTRecord generates both "old" and "new" TXT records.
-// Once we decide to drop old format we need to drop toTXTName() and rename toNewTXTName
+// generateTXTRecord generates TXT records in either both formats (old and new) or new format only,
+// depending on the newFormatOnly configuration. The old format is maintained for backwards
+// compatibility but can be disabled to reduce the number of DNS records.
 func (im *TXTRegistry) generateTXTRecord(r *endpoint.Endpoint) []*endpoint.Endpoint {
 	endpoints := make([]*endpoint.Endpoint, 0)
 
-	if !im.txtEncryptEnabled && !im.mapper.recordTypeInAffix() && r.RecordType != endpoint.RecordTypeAAAA {
+	// Create legacy format record by default unless newFormatOnly is true
+	if !im.newFormatOnly && !im.txtEncryptEnabled && !im.mapper.recordTypeInAffix() && r.RecordType != endpoint.RecordTypeAAAA {
 		// old TXT record format
 		txt := endpoint.NewEndpoint(im.mapper.toTXTName(r.DNSName), endpoint.RecordTypeTXT, r.Labels.Serialize(true, im.txtEncryptEnabled, im.txtEncryptAESKey))
 		if txt != nil {
@@ -224,7 +236,8 @@ func (im *TXTRegistry) generateTXTRecord(r *endpoint.Endpoint) []*endpoint.Endpo
 			endpoints = append(endpoints, txt)
 		}
 	}
-	// new TXT record format (containing record type)
+
+	// Always create new format record
 	recordType := r.RecordType
 	// AWS Alias records are encoded as type "cname"
 	if isAlias, found := r.GetProviderSpecificProperty("alias"); found && isAlias == "true" && recordType == endpoint.RecordTypeA {