stellar#4483: fixed the continue vs start value checks

exp/services/ledgerexporter/main.go

@@ -72,18 +72,23 @@ func main() {
 	// Build the appropriate range for the given backend state.
 	startLedger := uint32(*startingLedger)
 	endLedger := uint32(*endingLedger)
-	if startLedger < 2 {
-		logger.Fatalf("-start-ledger must be >= 2")
-	}
-	if endLedger != 0 && endLedger < startLedger {
-		logger.Fatalf("-end-ledger must be >= -start-ledger")
-	}
+
+	logger.Infof("processing requested range of -start-ledger=%v, -end-ledger=%v", startLedger, endLedger)
 	if *continueFromLatestLedger {
 		if startLedger != 0 {
 			logger.Fatalf("-start-ledger and -continue cannot both be set")
 		}
 		startLedger = readLatestLedger(target)
+		logger.Infof("continue flag was enabled, next ledger found was %v", startLedger)
 	}
+
+	if startLedger < 2 {
+		logger.Fatalf("-start-ledger must be >= 2")
+	}
+	if endLedger != 0 && endLedger < startLedger {
+		logger.Fatalf("-end-ledger must be >= -start-ledger")
+	}
+
 	var ledgerRange ledgerbackend.Range
 	if endLedger == 0 {
 		ledgerRange = ledgerbackend.UnboundedRange(startLedger)

services/horizon/docker/ledgerexporter/ledgerexporter.yml

@@ -18,7 +18,7 @@ data:
   # when using core 'on disk', the earliest ledger to get streamed out after catchup to 2, is 3
   # whereas on in-memory it streas out 2, adjusted here, otherwise horizon ingest will abort
   # and stop process with error that ledger 3 is not <= expected ledger of 2.    
-  #START: "3"
+  START: "0"
   END: "0"
 
   # can only have CONTINUE or START set, not both.