Remove --stellar-core-url check when DISABLE_TX_SUB=true, INGEST=false (

#5126)

* remove --stellar-core-url check

* Update parameters_test.go

services/horizon/internal/app.go

@@ -210,6 +210,9 @@ func isLocalAddress(url string, port uint) bool {
 func (a *App) UpdateCoreLedgerState(ctx context.Context) {
 	var next ledger.CoreStatus
 
+	if a.config.StellarCoreURL == "" {
+		return
+	}
 	// #4446 If the ingestion state machine is in the build state, the query can time out
 	// because the captive-core buffer may be full. In this case, skip the check.
 	if a.config.CaptiveCoreToml != nil &&

services/horizon/internal/flags.go

@@ -738,7 +738,7 @@ func NewAppFromFlags(config *Config, flags support.ConfigOptions) (*App, error)
 		return nil, err
 	}
 	// Validate app-specific arguments
-	if config.StellarCoreURL == "" {
+	if (!config.DisableTxSub || config.Ingest) && config.StellarCoreURL == "" {
 		return nil, fmt.Errorf("flag --%s cannot be empty", StellarCoreURLFlagName)
 	}
 

services/horizon/internal/integration/parameters_test.go

@@ -438,6 +438,20 @@ func TestDisableTxSub(t *testing.T) {
 		test.WaitForHorizon()
 		test.Shutdown()
 	})
+	t.Run("do not require stellar-core-url when both DISABLE_TX_SUB=true and INGEST=false", func(t *testing.T) {
+		localParams := integration.MergeMaps(networkParamArgs, map[string]string{
+			horizon.NetworkFlagName:      "testnet",
+			horizon.IngestFlagName:       "false",
+			horizon.DisableTxSubFlagName: "true",
+		})
+		testConfig := integration.GetTestConfig()
+		testConfig.HorizonIngestParameters = localParams
+		testConfig.SkipCoreContainerCreation = true
+		test := integration.NewTest(t, *testConfig)
+		err := test.StartHorizon()
+		assert.NoError(t, err)
+		test.Shutdown()
+	})
 }
 
 func TestDeprecatedOutputs(t *testing.T) {