gunicorn 无法启动 flask 服务器：ModuleNotFoundError：没有名为“请求”的模块

Question

Flask server runs perfectly fine but when running it with gunicorn, it shows the following error:

[2020-07-08 14:58:33 +0000] [27561] [INFO] Starting gunicorn 20.0.4
[2020-07-08 14:58:33 +0000] [27561] [INFO] Listening at: http://172.20.31.202:5000 (27561)
[2020-07-08 14:58:33 +0000] [27561] [INFO] Using worker: sync
[2020-07-08 14:58:33 +0000] [27564] [INFO] Booting worker with pid: 27564
[2020-07-08 14:58:34 +0000] [27564] [ERROR] Exception in worker process
Traceback (most recent call last):
  File "/usr/local/lib/python3.7/dist-packages/gunicorn/arbiter.py", line 583, in spawn_worker
    worker.init_process()
...
...
  File "/root/customer-account-automation/wsgi.py", line 7, in <module>
    from app import app as application
  File "/root/customer-account-automation/app.py", line 6, in <module>
    import requests
ModuleNotFoundError: No module named 'requests'
[2020-07-08 14:58:34 +0000] [27564] [INFO] Worker exiting (pid: 27564)
[2020-07-08 14:58:34 +0000] [27561] [INFO] Shutting down: Master
[2020-07-08 14:58:34 +0000] [27561] [INFO] Reason: Worker failed to boot.

I am not doubting the package installation because it already works with flask run .

This is the wsgi.py code

#!/usr/bin/python3
import sys
import logging
logging.basicConfig(stream=sys.stderr)

from app import app as application
if __name == "__main__":
    application.run()

and the pipenv site-packages directory contains both requests and gunicorn as shown below:

(customer-account-automation) root@jsd-user-management:~/customer-account-automation# ll /root/.local/share/virtualenvs/customer-account-automation-gLS21FFx/lib/python3.7/site-packages/
...
drwxr-xr-x  7 root root   4096 Jul  8 15:14 gunicorn/
drwxr-xr-x  2 root root   4096 Jul  8 15:14 gunicorn-20.0.4.dist-info/
drwxr-xr-x  3 root root   4096 Jul  8 14:39 requests/
drwxr-xr-x  2 root root   4096 Jul  8 14:39 requests-2.24.0.dist-info/
drwxr-xr-x  4 root root   4096 Jul  8 14:39 requests_oauthlib/
drwxr-xr-x  2 root root   4096 Jul  8 14:39 requests_oauthlib-1.3.0.dist-info/
drwxr-xr-x 10 root root   4096 Jul  8 14:39 requests_toolbelt/
drwxr-xr-x  2 root root   4096 Jul  8 14:39 requests_toolbelt-0.9.1.dist-info/
...

What could be there that gunicorn fails to import Requests but flask run succeeds? Could it be related to the pipenv?

Answer 1

It looks like the error is coming from a worker process. These will probably be opening subprocesses in python and may be calling the wrong version of python on your system - a version that doesn't have requests installed.

The config of gunicorn allows you to specify additions to the python path at runtime.

class PythonPath(Setting):
    name = "pythonpath"
    section = "Server Mechanics"
    cli = ["--pythonpath"]
    meta = "STRING"
    validator = validate_string
    default = None
    desc = """\
        A comma-separated list of directories to add to the Python path.
        e.g.
        ``'/home/djangoprojects/myproject,/home/python/mylibrary'``.
        """

You could try adding the location of the requests module when you run gunicorn. You can find where requests is by running pip show requests .

> pip show requests
Name: requests
Version: 2.23.0
...
Location: /root/.local/share/virtualenvs/customer-account-automation-gLS21FFx/lib/python3.7/site-packages/

Then append the location to whatever command you use for gunicorn:

gunicorn --pythonpath /root/.local/share/virtualenvs/customer-account-automation-gLS21FFx/lib/python3.7/site-packages/