ApacheWebServerSetup

1. Step One— Install and Enable mod_wsgi
    -> install mod_wsgi: sudo apt-get install libapache2-mod-wsgi-py3
    -> enable mod_wsgi: sudo a2enmod wsgi 
    
2. Step Two - Create the App
    -> web application
    -> api application
    -> database setup (chmod write permission for CRUD functionality)
    
3. Step Three
    - Install Flask
    
    -> install/update pip: sudo apt-get install python-pip 
    -> install virtualenv: sudo pip install virtualenv 
    -> activating the virtual environment: source venv/bin/activate 
    -> install flask: sudo pip3 install flask 
    -> run __init__.py : sudo python3 __init__.py 
    
4. Step Four 
    – Configure and Enable a New Virtual Host
    
    -> sudo nano /etc/apache2/sites-available/APIApp.conf
    -> configure as followed:
      <VirtualHost *:80>
		    ServerName server.yangyaochia.com
		      ServerAdmin root@server.yangyaochia.com
		      WSGIScriptAlias / /var/www/APIApp/apiapp.wsgi
		      <Directory /var/www/APIApp/APIApp/>
			      Order allow,deny
			      Allow from all
		      </Directory>
		      Alias /static /var/www/APIApp/APIApp/static
		      <Directory /var/www/APIApp/APIApp/static/>
			      Order allow,deny
			      Allow from all
		      </Directory>
		    ErrorLog ${APACHE_LOG_DIR}/error.log
		    LogLevel warn
		    CustomLog ${APACHE_LOG_DIR}/access.log combined
      </VirtualHost>
    -> enable virtual host: sudo a2ensite APIApp
    
    - What if you want to configure multiple virtual hosts on the same machine? 
    -> you could as well configure multiple virtual host with different host names by the same way as described as above.

5. Step Five – Create the .wsgi File
    -> cd /var/www/APIApp
    -> sudo nano apiapp.wsgi 
    -> add following lines
          #!/usr/bin/python
          activate_this = '/var/www/APIApp/APIApp/venv/bin/activate_this.py'
	  // the above path should be absolute path
	  with open(activate_this) as file_:
    		exec(file_.read(), dict(__file__=activate_this))
	  import sys
          import logging
          logging.basicConfig(stream=sys.stderr)
          sys.path.insert(0,"/var/www/APIApp/")

          from FlaskApp import app as application
          application.secret_key = 'super_key'
6. Step Six - Restart Apache2
    -> sudo service apache2 restart 
    -> and you will be able to access your virtual host without any further issues.
    -> use cURL/POSTMAN/browser to test the CRUD functionality
    -> if there are issues getting the result, try the command below to see the root cause
       sudo tail /var/log/apache2/error.log
    
7. Step Seven - Verification
    - need to verify whether your mod_wsgi indeed use the correct venv python
    - execute "pip list" on terminal 
    	to List installed packages under normal environment and virtual environment
    - if finding out flask package in normal environment, you should uninstall with "pip uninstall flask"
    - mod_wsgi should be working only with venv python now