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"OSError: [Errno 88] Socket operation on non-socket" by flipflop

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When trying to deploy an Flask application to my LAMP server, I got an error from flipflop, a FastCGI/WSGI gateway which enables my application to speak the FastCGI protocol.

~/minimal/run.py 

from flask import Flask
from flipflop import WSGIServer

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'hello, world'

if __name__ == '__main__':
    WSGIServer(app).run()

Relevant part of the Apache configuration file, i.e. /etc/httpd/conf/httpd.conf:

<VirtualHost *:80>
    ScriptAlias / /home/apps/minimal/run.py
    ErrorLog /var/log/httpd/error_log
</VirtualHost>

Error report by Apache/2.2.15:

[apps@kernod0 ~]$ sudo head -n 20 /var/log/httpd/error_log
[sudo] password for apps: 
[Wed Aug 16 16:39:16 2017] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Wed Aug 16 16:39:16 2017] [notice] Digest: generating secret for digest authentication ...
[Wed Aug 16 16:39:16 2017] [notice] Digest: done
[Wed Aug 16 16:39:16 2017] [notice] Apache/2.2.15 (Unix) DAV/2 mod_fcgid/2.3.9 configured -- resuming normal operations
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219] Traceback (most recent call last):
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219]   File "/home/apps/minimal/run.py", line 12, in <module>
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219]     WSGIServer(app).run()
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/flipflop.py", line 938, in run
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219]     sock.getpeername()
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219] socket.error: [Errno 88] Socket operation on non-socket
[Wed Aug 16 16:39:16 2017] [error] [client 100.116.224.219] Premature end of script headers: run.py
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253] Traceback (most recent call last):
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253]   File "/home/apps/minimal/run.py", line 12, in <module>
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253]     WSGIServer(app).run()
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/flipflop.py", line 938, in run
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253]     sock.getpeername()
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253] socket.error: [Errno 88] Socket operation on non-socket
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.253] Premature end of script headers: run.py
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.205] Traceback (most recent call last):
[Wed Aug 16 16:39:17 2017] [error] [client 100.116.226.205]   File "/home/apps/minimal/run.py", line 12, in <module>

In addition, even without using flipflop, it still doesn't work:

~/minimal/run.py 

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'hello, world'

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

Error output:

[apps@kernod0 ~]$ sudo cat /var/log/httpd/error_log
[Wed Aug 16 20:47:24 2017] [notice] suEXEC mechanism enabled (wrapper: /usr/sbin/suexec)
[Wed Aug 16 20:47:24 2017] [notice] Digest: generating secret for digest authentication ...
[Wed Aug 16 20:47:24 2017] [notice] Digest: done
[Wed Aug 16 20:47:24 2017] [notice] Apache/2.2.15 (Unix) DAV/2 mod_fcgid/2.3.9 configured -- resuming normal operations
[Wed Aug 16 20:47:33 2017] [error] [client 100.116.226.182]  * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] Traceback (most recent call last):
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/run.py", line 11, in <module>
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] app.run()
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/flask/app.py", line 841, in run
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] run_simple(host, port, self, **options)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/werkzeug/serving.py", line 739, in run_simple
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] inner()
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/werkzeug/serving.py", line 699, in inner
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] fd=fd)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/werkzeug/serving.py", line 593, in make_server
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] passthrough_errors, ssl_context, fd=fd)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/home/apps/minimal/flask/lib/python2.6/site-packages/werkzeug/serving.py", line 504, in __init__
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] HTTPServer.__init__(self, (host, int(port)), handler)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/usr/lib64/python2.6/SocketServer.py", line 412, in __init__
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] self.server_bind()
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/usr/lib64/python2.6/BaseHTTPServer.py", line 108, in server_bind
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] SocketServer.TCPServer.server_bind(self)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "/usr/lib64/python2.6/SocketServer.py", line 423, in server_bind
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]     
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] self.socket.bind(self.server_address)
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190]   File "<string>", line 1, in bind
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] socket
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] .
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] error
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] : 
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] [Errno 98] Address already in use
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] 
[Wed Aug 16 20:47:37 2017] [error] [client 100.116.226.190] Premature end of script headers: run.py
[Wed Aug 16 20:48:33 2017] [warn] [client 100.116.226.182] Timeout waiting for output from CGI script /home/apps/minimal/run.py
[Wed Aug 16 20:48:33 2017] [error] [client 100.116.226.182] Script timed out before returning headers: run.py
[Wed Aug 16 20:49:33 2017] [warn] [client 100.116.226.182] Timeout waiting for output from CGI script /home/apps/minimal/run.py
apache sockets flask fastcgi mod-fcgid
Original Q&A
4

There are 4 best solutions below

3
Miguel Grinberg On

You can't run the fastcgi script from the terminal. This script is supposed to be executed by Apache. Typically you have it configured in a ScriptAlias directive in your Apache config file.

0
Fedor Dikarev On

In general you should use mod_fastcgi and configuration simillar to:

<VirtualHost *:8091>
  ServerName helloworld.local
  DocumentRoot /home/fe/work/flipflop
  FastCgiServer /home/fe/work/flipflop/run.py
  ScriptAlias / /home/fe/work/flipflop/run.py
    <Location />
      Options none
    </Location>
</VirtualHost>

So it will make run your script as FastCgi, but I'm not familiar with flipflop and can't make it works.

But if you are not limited to flipflop you could use uwsgi to run your application, mod_wsgi to run it with Apache (read more details in Flask documentation) or use Flask-Script runserver command to run your application in debug server (see example in Flask-Script documentation

0
Soleil On

First things first, looks like you're having already some app running/listening on port 5000. You might want to find which with sudo sockstat |grep 5000 and then configure Apache consequently, or kill the process/service using localhost:5000.

Second, looks like your virtual host is not taken into account/not fully configured.

1
kchomski On

I've managed to run your example, but there are some tweaking involved to make it work.
You might need to change paths on your system, because from your logs it seems that you're using system that runs python2.6 and older apache version which still uses httpd file.
If it is possible I would advise you to upgrade your environment.

Here is a step-by-step working solution:

1.Install virtualenvwrapper:

sudo -EH pip2 install virtualenvwrapper

2.Activte it:

source /usr/local/bin/virtualenvwrapper.sh

3.Create virtual env: 

mkvirtualenv minimal

4.Install flask and flup: 

pip install -U flask flup

flipflop is not working for me, but as it's README states

This module is a simplified fork of flup, written by Allan Saddi. It only has the FastCGI part of the original module.

so you can safely use it.

5.Install apache2: 

sudo apt-get install apache2

6.Install libapache2-mod-fastcgi:

sudo apt-get install libapache2-mod-fastcgi

7.Create /var/www/minimal/run.py:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'hello, world'

8.Create /var/www/minimal/minimal.fcgi:

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

activate_this = '/home/some_user/.virtualenvs/minimal/bin/activate_this.py'
execfile(activate_this, dict(__file__=activate_this))

sys.path.insert(0,"/var/www/minimal/")

from flup.server.fcgi import WSGIServer
from run import app

if __name__ == '__main__':
    WSGIServer(app).run()

9.Make minimal.fcgi executable:

sudo chmod +x minimal.fcgi

10.Create minimal.conf file (in /etc/apache2/sites-available on my server):

FastCgiServer /var/www/minimal/minimal.fcgi -idle-timeout 300 -processes 5

<VirtualHost *:80>
    ServerName YOUR_IP_ADDRESS
    DocumentRoot /var/www/minimal/

    AddHandler fastcgi-script fcgi
    ScriptAlias / /var/www/minimal/minimal.fcgi/

    <Location />
        SetHandler fastcgi-script
    </Location>
</VirtualHost>

11.Enable new site:

sudo a2ensite minimal.conf

12.Change /var/www/ ownership to www-data user:

sudo chown -R www-data:www-data /var/www/

13.Restart apache2:

sudo /etc/init.d/apache2 restart

And voila! :)

If you visit your server address you should see hello, world in your browser: enter image description here

Also when restarting apache you can view FastCGI starting in apache's error.log:

[Thu Aug 24 16:33:09.354544 2017] [mpm_event:notice] [pid 17375:tid 139752788969344] AH00491: caught SIGTERM, shutting down
[Thu Aug 24 16:33:10.414829 2017] [mpm_event:notice] [pid 17548:tid 139700962228096] AH00489: Apache/2.4.18 (Ubuntu) mod_fastcgi/mod_fastcgi-SNAP-0910052141 configured -- resuming normal operations
[Thu Aug 24 16:33:10.415033 2017] [core:notice] [pid 17548:tid 139700962228096] AH00094: Command line: '/usr/sbin/apache2'
[Thu Aug 24 16:33:10.415651 2017] [:notice] [pid 17551:tid 139700962228096] FastCGI: process manager initialized (pid 17551)
[Thu Aug 24 16:33:10.416135 2017] [:warn] [pid 17551:tid 139700962228096] FastCGI: server "/var/www/minimal/minimal.fcgi" started (pid 17556)
[Thu Aug 24 16:33:11.416571 2017] [:warn] [pid 17551:tid 139700962228096] FastCGI: server "/var/www/minimal/minimal.fcgi" started (pid 17618)
[Thu Aug 24 16:33:12.422058 2017] [:warn] [pid 17551:tid 139700962228096] FastCGI: server "/var/www/minimal/minimal.fcgi" started (pid 17643)
[Thu Aug 24 16:33:13.422763 2017] [:warn] [pid 17551:tid 139700962228096] FastCGI: server "/var/www/minimal/minimal.fcgi" started (pid 17651)
[Thu Aug 24 16:33:14.423536 2017] [:warn] [pid 17551:tid 139700962228096] FastCGI: server "/var/www/minimal/minimal.fcgi" started (pid 17659)

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