Flask - WSGI - No module named 'flask'

问题

I've been following Sentdex' Flask tutorial. He's using a Venv to set up his Flask, but didn't set his Python up to work with a Venv. I've tried installing Flask globally - yet it still doesn't work. Trying to browse to the server returns a 500 Internal Server Error

I'm getting the usual no module named flaskerror.

errorFGL.log

[Sun Feb 05 11:22:32.043925 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814] mod_wsgi (pid=26340): Target WSGI script '/var/www-fgl/FlaskApp/flaskapp.wsgi' cannot be loaded as Python module.
[Sun Feb 05 11:22:32.044105 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814] mod_wsgi (pid=26340): Exception occurred processing WSGI script '/var/www-fgl/FlaskApp/flaskapp.wsgi'.
[Sun Feb 05 11:22:32.044243 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814] Traceback (most recent call last):
[Sun Feb 05 11:22:32.045011 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814]   File "/var/www-fgl/FlaskApp/flaskapp.wsgi", line 8, in <module>
[Sun Feb 05 11:22:32.045070 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814]     from FlaskApp import app as application
[Sun Feb 05 11:22:32.045549 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814]   File "/var/www-fgl/FlaskApp/FlaskApp/__init__.py", line 1, in <module>
[Sun Feb 05 11:22:32.045594 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814]     from flask import Flask
[Sun Feb 05 11:22:32.045689 2017] [wsgi:error] [pid 26340:tid 118578538694400] [client 86.52.205.25:49814] ImportError: No module named 'flask'

__init__.py

from flask import Flask

app = Flask(__name__)

@app.route('/')
def homepage():
    return "Success"

if __name__ == "__main__":
    app.run()

flaskapp.wsgi

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

sys.path.insert(0,"/var/www-fgl/FlaskApp/")

from FlaskApp import app as application
application.secret_key = '[REDACTED]'

fgl-database.conf

<VirtualHost *:80>
        ServerName [REDACTED]
        WSGIScriptAlias / /var/www-fgl/FlaskApp/flaskapp.wsgi
        <Directory /var/www-fgl>
            Require all granted
        </Directory>
        Alias /static /var/www-fgl/FlaskApp/FlaskApp/static
        <Directory /var/www-fgl/FlaskApp/FlaskApp/static/>
            Require all granted
        </Directory>
        ErrorLog ${APACHE_LOG_DIR}/errorFGL.log
        LogLevel warn
        CustomLog ${APACHE_LOG_DIR}/accessFGL.log combined




</VirtualHost>

回答1:

As is polite behaviour when finding the solution, I googled around a bit more, and somehow managed to find a solution from a YouTube commment by Nathan Nichols here:

https://www.digitalocean.com/community/tutorials/how-to-run-django-with-mod_wsgi-and-apache-with-a-virtualenv-python-environment-on-a-debian-vps

1. Edit /etc/apache2/sites-available/FlaskApp.conf

2. Add the following two lines before the "WSGIScriptAlias" line:

   WSGIDaemonProcess FlaskApp python-path=/var/www/FlaskApp:/var/www/FlaskApp/FlaskApp/venv/lib/python2.7/site-packages
   WSGIProcessGroup FlaskApp
   

3. Restart Apache with "service apache2 restart"

I of course replaced the Python version with python3.5, which is what I'm running.

回答2:

First install python-virtualenv

Then from the Flask app directory where you put the wigs python files run

virtualenv env

This will create env directory inside the Flask directory and contains the local python installation.

Next activate the virtual environment by this command source env/bin/activate

After activating the virtual environment run pip install flask

Run pip --version

You will see something like this

pip 19.0.3 from /var/www/html/flaskapp/env/local/lib/python2.7/site-packages/pip (python 2.7)

Copy this python path

 WSGIDaemonProcess FlaskApp python-path=/var/www/html/flaskapp:/var/www/html/flaskapp/env/local/lib/python2.7/site-packages
WSGIProcessGroup FlaskApp

Add above lines in FlaskApp.conf in sites-available directory of apache

Note put python-path what you get after running pip --version

回答3:

Nothing worked for me, but I just add below line in starting of my .py and .wsgi file voila it worked:

import sys
sys.path.append('/home/ubuntu/pythonVirtual/lib/python3.6/site-packages)

here pythonVirtual is my virtual directory for Python

回答4:

1. According to http://modwsgi.readthedocs.io/en/develop/user-guides/virtual-environments.html.

2. You should edit /etc/apache2/sites-available/FlaskApp.conf

3. Add these above the WSGIScriptAlias

   WSGIDaemonProcess FlaskApp python-home=/var/www/FlaskApp/FlaskApp/venv/FlaskApp WSGIProcessGroup FlaskApp

I met the same problem and fix it by the way.

来源：https://stackoverflow.com/questions/42050982/flask-wsgi-no-module-named-flask