Minor ledgerexporter infrastructure improvements (#4461)

* Push the stellar/horizon-ledgerexporter docker image when pushing to the lighthorizon branch
* Fix the ledger exporter aws batch jobs when running on the first batch

.github/workflows/horizon.yml

@@ -2,7 +2,7 @@ name: Horizon
 
 on:
   push:
-    branches: [master]
+    branches: [master, lighthorizon]
   pull_request:
 
 jobs:
@@ -146,6 +146,6 @@ jobs:
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
 
-      - if: github.ref == 'refs/heads/master'
+      - if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/lighthorizon'
         name: Push to DockerHub
         run: docker push stellar/horizon-ledgerexporter:latest

services/horizon/docker/ledgerexporter/start

@@ -26,17 +26,14 @@ if [ ! -z "$AWS_BATCH_JOB_ARRAY_INDEX" ]; then
 	# AWS_BATCH_JOB_ARRAY_INDEX=2: [191, 255]
 	# AWS_BATCH_JOB_ARRAY_INDEX=3: [255, 319]
 	# ...
+	START=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER"`
+	END=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER" + "$BATCH_SIZE"`
 
-	if [ $BATCH_START_LEDGER -eq 1 ]; then
-		export START=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER" - "2"`
-		export END=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER" + "$BATCH_SIZE" - "2"`
-		if [ $START -eq -1 ]; then
-			export START="1"
-		fi
-	else
-		export START=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER"`
-		export END=`expr "$BATCH_SIZE" \* "$AWS_BATCH_JOB_ARRAY_INDEX" + "$BATCH_START_LEDGER" + "$BATCH_SIZE"`
+	if [ "$START" -lt 2 ]; then
+	  # The minimum ledger expected by the ledger exporter is 2
+	  START=2
 	fi
+
 fi
 
 echo "START: $START END: $END"