add proper healthcheck for postgres and depends on statement

compose.postgres.yml

@@ -2,6 +2,8 @@ version: "3.8"
 
 services:
   app:
+    depends_on:
+      - db
     environment:
       - GTS_DB_PORT=5432
       - GTS_DB_TYPE=postgres
@@ -34,7 +36,12 @@ services:
     configs:
       - source: pg_backup
         target: /pg_backup.sh
-        mode: 0555
+        mode: 555
+    healthcheck:
+      test: [ "CMD-SHELL", "pg_isready" ]
+      interval: 10s
+      timeout: 5s
+      retries: 5
 
 secrets:
   db_password:
@@ -44,6 +51,7 @@ secrets:
 volumes:
   db:
 
+
 configs:
   pg_backup:
     name: ${STACK_NAME}_pg_backup_${PG_BACKUP_VERSION}