add Docker image mailhog for service SMTP

docker-compose.yml

@@ -36,6 +36,42 @@ services:
     volumes:
       - db_isolated_data:/var/lib/postgresql/data
 
+  backend:
+    depends_on:
+      - db
+      - db_isolated
+    build:
+      context: .
+      target: backend
+      args:
+        PYTHON_DEBUG: ${PYTHON_DEBUG}
+    ports:
+      - ${FLASK_PORT}:5000
+      - 10001:10001
+    restart: always
+    env_file:
+      - .env
+    environment:
+      DB_PASSWORD_FILE: /run/secrets/db_password
+      ISOLATED_DB_PASSWORD_FILE: /run/secrets/db_isolated_password
+    secrets:
+      - db_password
+      - db_isolated_password
+    volumes:
+      - ./:/app:cached
+
+  smtp:
+    image: mailhog/mailhog
+    ports:
+      - 1025:1025
+      - 8025:8025
+
+secrets:
+  db_password:
+    file: ./db_password
+  db_isolated_password:
+    file: ./db_isolated_password
+
 volumes:
   db_data:
   db_isolated_data: