tag replacement in docker-compose

docker-compose.yaml

@@ -1,7 +1,7 @@
 version: '3.8'
 services:
     java-maven-app:
-      image: nanajanashia/demo-app:java-maven-1.0
+      image: "nanajanashia/demo-app:${TAG}"
       ports:
         - 8080:8080
     postgres:

server-cmds.sh

@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
 
+export TAG=java-maven-1.0
 docker-compose -f docker-compose.yaml up --detach
 echo "success"