FirebaseFlaskAPI部署错误：/bin/sh:1:exec:gunicorn:未找到

Question

我正试着把我的烧瓶架放在火场上。我在看这篇文章：https://medium.com/firebase-developers/hosting-flask-servers-on-firebase-from-scratch-c97cfb204579

我在运行gcloud beta run deploy --image gcr.io/id/flask-fire时遇到此错误

以下是相关信息：

Deploying container to Cloud Run service [flask-fire] in project [project-name] region [europe-west1]
Deploying...
  Creating Revision... Cloud Run error: Container failed to start. Failed to start and then listen on the port defined by the PORT environment variable. Logs for this rev
  ision might contain more information.

/bin/sh: 1: exec: gunicorn: not found

这是我的Dockerfile：

# 1
FROM python:3.9

# 2
RUN pip install gunicorn
RUN pip3 install gunicorn

# 3
COPY src/ /app
WORKDIR /app

# 4
ENV PORT 8080

# 5
CMD exec gunicorn --bind :$PORT --workers 1 --threads 8 app:application

我做错了什么？提前谢谢你

此外，这是我的文件夹结构：