Installation Notes for Flask App on Ubuntu 14.04 LTS using gUnicorn

Followed these excellent directions from Real Python and modified for python3 and Ubuntu 14.04.
Start with updating ubuntu and loading additional packages

sudo apt-get updatesudo apt-get install -y python3 python3-pip nginx mongodb supervisorsudo pip3 install virtualenv



sudo mkdir /var/wwwsudo chown ubuntu:ubuntu /var/wwwmkdir /var/www/flask-appmkdir /var/www/flask-app/logscd /var/www/flask-app

Setup virtualenv

virtualenv flask_env
source flask_env/bin/activate
pip install -r requirements.txt
pip install gunicorn

Setup nginx

sudo /etc/init.d/nginx start
sudo rm /etc/nginx/sites-enabled/default
sudo touch /etc/nginx/sites-available/flask-app
sudo ln -s /etc/nginx/sites-available/flask-app /etc/nginx/sites-enabled/flask-app
sudo vim /etc/nginx/sites-enabled/flask-app

Add the following to the nginx flask-app conf file being edited

server {
    location / {
        proxy_pass http://127.0.0.1:8000;
    }
    location /static {
        alias  /var/www/flask-app/flAsk-app/static;
    }
}

sudo service nginx reload

Setup gunicorn start file

Setup bash script to run gunicorn

cd /var/www/flask-app
touch gunicorn_start
chmod a+x gunicorn_start
vim gunicorn_start

Insert the following into the gunicorn_start bash script

#!/bin/bash

NAME="flAsk-app"
FLASKDIR=/var/www/flask-app
VENVDIR=/var/www/flask-app/flask_env
SOCKFILE=/var/www/flask-app/sock
USER=ubuntu

GROUP=ubuntu
NUM_WORKERS=3

echo "Starting $NAME"

# activate the virtualenv
cd $VENVDIR
source bin/activate

export PYTHONPATH=$FLASKDIR:$PYTHONPATH

# Create the run directory if it doesn't exist
RUNDIR=$(dirname $SOCKFILE)
test -d $RUNDIR || mkdir -p $RUNDIR

# Start your unicorn
exec gunicorn runserver:app -b 127.0.0.1:8000 \
  --name $NAME \
  --workers $NUM_WORKERS \
  --user=$USER --group=$GROUP \
  --log-level=debug \

Setup Supervisor

This will run and restart the Flask application when the application files are changed.

cd /etc/supervisor/conf.d
sudo vim flask-app.conf

Insert the following into the flask-app.conf file:

[program:flask-app]
command = /var/www/flask-app/gunicorn_start
user = ubuntu
stdout_logfile = /var/www/flask-app/logs/gunicorn_supervisor.log
redirect_stderr = true

Start flask-app gunicorn:

sudo supervisorctl update
sudo supervisorctl status

You can use the following commands as well:

sudo supervisorctl start flask-app
sudo supervisorctl start all
sudo supervisorctl help|avail|stop|restart

Test that the application is running