fix(flags): restore --min-ttl option

docs/flags.md

@@ -175,6 +175,7 @@
 | `--[no-]once` | When enabled, exits the synchronization loop after the first iteration (default: disabled) |
 | `--[no-]dry-run` | When enabled, prints DNS record changes rather than actually performing them (default: disabled) |
 | `--[no-]events` | When enabled, in addition to running every interval, the reconciliation loop will get triggered when supported sources change (default: disabled) |
+| `--min-ttl=0s` | Configure global TTL for records in duration format. This value is used when the TTL for a source is not set or set to 0. (optional; examples: 1m12s, 72s, 72) |
 | `--log-format=text` | The format in which log messages are printed (default: text, options: text, json) |
 | `--metrics-address=":7979"` | Specify where to serve the metrics and health check endpoint (default: :7979) |
 | `--log-level=info` | Set the level of logging. (default: info, options: panic, debug, info, warning, error, fatal) |

pkg/apis/externaldns/types.go

@@ -313,6 +313,7 @@ var defaultConfig = &Config{
 	ManagedDNSRecordTypes:        []string{endpoint.RecordTypeA, endpoint.RecordTypeAAAA, endpoint.RecordTypeCNAME},
 	MetricsAddress:               ":7979",
 	MinEventSyncInterval:         5 * time.Second,
+	MinTTL:                       0,
 	Namespace:                    "",
 	NAT64Networks:                []string{},
 	NS1Endpoint:                  "",
@@ -801,6 +802,7 @@ func bindFlags(b FlagBinder, cfg *Config) {
 	b.BoolVar("once", "When enabled, exits the synchronization loop after the first iteration (default: disabled)", defaultConfig.Once, &cfg.Once)
 	b.BoolVar("dry-run", "When enabled, prints DNS record changes rather than actually performing them (default: disabled)", defaultConfig.DryRun, &cfg.DryRun)
 	b.BoolVar("events", "When enabled, in addition to running every interval, the reconciliation loop will get triggered when supported sources change (default: disabled)", defaultConfig.UpdateEvents, &cfg.UpdateEvents)
+	b.DurationVar("min-ttl", "Configure global TTL for records in duration format. This value is used when the TTL for a source is not set or set to 0. (optional; examples: 1m12s, 72s, 72)", defaultConfig.MinTTL, &cfg.MinTTL)
 
 	// Miscellaneous flags
 	b.EnumVar("log-format", "The format in which log messages are printed (default: text, options: text, json)", defaultConfig.LogFormat, &cfg.LogFormat, "text", "json")

pkg/apis/externaldns/types_test.go

@@ -224,6 +224,7 @@ var (
 		TXTCacheInterval:                              12 * time.Hour,
 		Interval:                                      10 * time.Minute,
 		MinEventSyncInterval:                          50 * time.Second,
+		MinTTL:                                        40 * time.Second,
 		Once:                                          true,
 		DryRun:                                        true,
 		UpdateEvents:                                  true,
@@ -370,6 +371,7 @@ func TestParseFlags(t *testing.T) {
 				"--dynamodb-table=custom-table",
 				"--interval=10m",
 				"--min-event-sync-interval=50s",
+				"--min-ttl=40s",
 				"--once",
 				"--dry-run",
 				"--events",
@@ -492,6 +494,7 @@ func TestParseFlags(t *testing.T) {
 				"EXTERNAL_DNS_TXT_NEW_FORMAT_ONLY":                               "1",
 				"EXTERNAL_DNS_INTERVAL":                                          "10m",
 				"EXTERNAL_DNS_MIN_EVENT_SYNC_INTERVAL":                           "50s",
+				"EXTERNAL_DNS_MIN_TTL":                                           "40s",
 				"EXTERNAL_DNS_ONCE":                                              "1",
 				"EXTERNAL_DNS_DRY_RUN":                                           "1",
 				"EXTERNAL_DNS_EVENTS":                                            "1",