Setup instructions for deploying a Flask app in Digital Ocean Droplet

1. log into droplet (it is assumed you have created your droplet with ssh enabled)

   ssh root@<your_droplet_public_ip>

2. install apache

   sudo apt-get update
   sudo apt-get install apache2

3. install and enable mod_wsgi

   sudo apt-get install libapache2-mog-wsgi python-dev
   sudo a2enmod wsgi

4. create the flask app

   cd /var/www
   git clone https://github.com/nshathish/flask-lab2.git
   cd flask-lab2

5. setup virtual environment and install flask

   sudo apt-get install python-pip
   sudo pip install virtualenv
   sudo virtualenv venv
   source venv/bin/activate
   sudo pip install Flask

   try running the app

   sudo python app.py

   if app is running ok, deactivate environgment

   deactivate

6. serving flask app with wsgi

   inside /var/www/flask-lab2

   nano flask_lab2.wsgi

   in flask_lab2.wsgi write the following

   import sys
   import logging
   logging.basicConfig(stream=sys.stderr)
   sys.path.insert(0, "/var/www/flask-lab2")
   from app import app as application

7. configure and enable virtual host

   sudo nano /etc/apache2/sites-available/flask-lab2.conf

   write the following in the flask-lab2.conf

   <VirtualHost *:80>
     ServerName flask-lab2.myserver.com
     ServerAdmin root@nshathish.com1
     WSGIScriptAlias / /var/www/flask-lab2/flask-lab2.wsgi
     WSGIDaemonProcess flask-lab2
     <Directory /var/www/flask-lab2>
         WSGIProcessGroup flask-lab2
         WSGIApplicationGroup %{GLBAL}
         Order deny,allow
         Allow from all
     </Directory>
     ErrorLog ${APACHE_LOG_DIR}/error.log
     LogLevel warn
     CustomLog ${APACHE_LOG_DIR}/access.log combined
   </VirtualHost>

8. disable the default site and enable flask-lab2

   sudo a2dissite 000-default.conf
   sudo a2ensite flask-lab2.conf
   sudo service apache2 reload

9. view your flask app in browser

   http://<your_public_ip>

Setup instuctions for deploying a flask application to AWS Ec2 instance running amazon-linux-2 (free tier)

sudo su
yum install python3-devel httpd httpd-devel gcc git -y
pip3 install mod_wsgi

after installing restart the machine

mod_wsgi-express start-server

if you see the server running, then mod_wsgi installation has been successful

mod_wsgi-express module-config >> /etc/httpd/conf/httpd.conf

this didn't work (gor permission denied error, even with sudo), so had to pipe that to a temp file and copy the contents manually to /etc/httpd/conf/httpd.conf

mod_wsgi-express module-config > temp.conf
cat temp.conf

this would look something like the following:

LoadModule wsgi_module "/usr/local/lib64/python3.7/site-packages/mod_wsgi/server/mod_wsgi-py37.cpython-37m-x86_64-linux-gnu.so"
WSGIPythonHome "/usr"

following on,

cd /var/www
git clone https://github.com/nshathish/flask-lab2.git
cd flask-lab2/
nano flask-lab2.wsgi

copy the following contents into the above file

import sys
import logging
logging.basicConfig(stream=sys.stderr)
sys.path.insert(0, "/var/www/flask-lab2")
from app import app as application

sudo nano /etc/httpd/conf.d/flask-lab2.conf

copy the following contents into the above file

<VirtualHost *:80>
  ServerName flask-lab2.myserver.com
  ServerAdmin root@nshathish.com1
  WSGIScriptAlias / /var/www/flask-lab2/flask-lab2.wsgi
  WSGIDaemonProcess flask-lab2
  <Directory /var/www/flask-lab2>
      WSGIProcessGroup flask-lab2
      WSGIApplicationGroup %{GLOBAL}
      Order deny,allow
      Allow from all
  </Directory>
  ErrorLog /var/log/httpd/error.log
  LogLevel warn
  CustomLog /var/log/httpd/access.log combined
</VirtualHost>

sudo service httpd restart
curl http://localhost

if you get Hello World! then your flask application is running on apache with mod_wsgi, successfully.