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

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 Flaskapp = Flask(__name__)@app.route('/')def hello_world():    return 'hello, world'

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

#!/usr/bin/pythonimport sysimport logginglogging.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 WSGIServerfrom run import appif __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:

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)

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.

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