在运行docker composite up并进入0.0.0..：8000/docs后，在fastapi项目x1c 0d1x中使用get方法时出现以下错误
.env文件内容

MONGODB_URL = mongodb://localhost:27017/

MONGO_HOST = "0.0.0.0"
MONGO_PORT = 27017
MONGO_USER = ""
MONGO_PASS = ""
DATABASE_NAME = "myDatabase"
TEST1_COLLECTION="TEST1_COLLECTION"
TEST2_COLLECTION="TEST2_COLLECTION"
TEST3_COLLECTION="TEST3_COLLECTION"

停靠文件内容：

FROM tiangolo/uvicorn-gunicorn-fastapi:python3.9
COPY ./requirements.txt /app/requirements.txt 
RUN pip install --no-cache-dir --upgrade -r /app/requirements.txt
COPY ./app /app/app
WORKDIR /app/app/
CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]

docker-compose.yml内容

version: "3.9"
services:
 app:
  build: .
  command: uvicorn app.main:app --host 0.0.0.0
  ports:
    - "8000:8000"
  depends_on:
  - db
 db:
   image: mongo
   ports:
     - "27017:27017"
   volumes:
     - ./data:/data/db

我做错了什么，因为我只需要使用docker中的环境变量并运行应用程序？