Fix default port mapping and indentation

Signed-off-by: Anca Iordache <anca.iordache@docker.com>

spring-postgres/docker-compose.yaml

@@ -3,27 +3,27 @@ services:
   backend:
     build: backend
     ports:
-    - 80:8080
+      - 8080:8080
     environment:
-      POSTGRES_DB: example
+      - POSTGRES_DB=example
     networks:
       - spring-postgres
   db:
-    environment:
-      POSTGRES_DB: example
-      POSTGRES_PASSWORD_FILE: /run/secrets/db-password
     image: postgres
     restart: always
     secrets:
-    - db-password
+      - db-password
     volumes:
-    - db-data:/var/lib/postgresql/data
+      - db-data:/var/lib/postgresql/data
     networks:
       - spring-postgres
+    environment:
+      - POSTGRES_DB=example
+      - POSTGRES_PASSWORD_FILE=/run/secrets/db-password
 volumes:
-  db-data: {}
+  db-data:
 secrets:
   db-password:
     file: db/password.txt
 networks:
-  spring-postgres: {}
+  spring-postgres: