我正在进行网上书店项目。我正在尝试在dockercompose.yml中设置环境变量

• 项目文件夹/settings.py*

SECRET_KEY = os.environ.get('SECRET_KEY')

• dockercompose.yml文件中的代码 *

version: '3.7'

services:
  web:
      build: .
      command: python /code/manage.py runserver 0.0.0.0:8000
      volumes:
          - .:/code
      ports:
          - 8000:8000
      depends_on:
          - db
      environment:
          - SECRET_KEY=my_secret_key
          - DEBUG=1

  db:
    image: postgres:11
    volumes:
      - postgres_data:/var/lib/postgresql/data/
volumes:
  postgres_data:

我在运行命令时收到以下错误

$docker-compose down

ERROR: Invalid interpolation format for "environment" option in service "web": "SECRET_KEY=my_secret_key"