Deployment: Nginx & uWSGI

These directions come primarily from a very helpful tutorial created by Vladik Khononov.

1. Install nginx.

   # This package will keep nginx up to date.
   $ sudo yum install epel-release
   $ sudo yum install nginx
   
   # Confirmation step:
   $ sudo service nginx start

   When you navigate to your server's public address in a browser, you should see a generic "Welcome to nginx" page.

2. Install uwsgi in your Library Simplified repo's virtual environment.

   # If you're not already in your LS repo, go there, e.g.
   $ cd YOUR_LS_APP_DIR
   
   # Pop into your Python environment & install uWSGI
   $ source env/bin/activate
   $ pip install uwsgi

3. Create an appropriately-named directory in a location where nginx will have access. We'll refer to it in the next step as YOUR_UWSGI_SOCKET_DIR. Make sure that both nginx and ec2-user has permissions.

   $ mkdir /var/www/circulation
   $ sudo chown nginx:nginx /var/www/circulation
   $ sudo chmod 777 /var/www/circulation
   

4. In your LS repo, configure nginx with an nginx.conf file. For the most up-to-date example, use the file found here. Be sure to change the uwsgi_pass variable to reference unix:YOUR_UWSGI_SOCKET_DIR/uwsgi.sock.

5. Then create a symbolic link to it and restart nginx.

   $ sudo ln -s /var/www/circulation/nginx.conf /etc/nginx/conf.d/circulation.conf
   $ sudo service nginx restart

   Now when you navigate to your server's address in a web browser, you should get a 502 error. Fantastic!

6. In your LS repo, configure uWSGI with an uwsgi.ini file. For the most up-to-date example, use the file found here. Be sure to set the base variable to YOUR_LS_APP_DIR, and the socket variable to YOUR_UWSGI_SOCKET_DIR/%n.sock

7. Enter the virtual environment, and confirm that your uWSGI configuration works.

   $ cd YOUR_LS_APP_DIR
   $ source env/bin/activate
   $ uwsgi --ini uwsgi.ini
   

   You'll see a single line of text in your terminal: [uWSGI] getting INI configuration from uwsgi.ini, followed by a blank link. Before ending the process, visit your server's address in the web browser, and you should an OPDS feed that represents your LS app! Make sure that if you're configuring the Metadata Wrangler, you try the /lookup route for a feed, as the home index is not currently being used.

8. If you experience errors during step #7, look to /var/log/nginx/errors.log and /var/log/uwsgi/emperor.log for information about what's going wrong.

9. Once things are working, run uWSGI in the background:

   $ source env/bin/activate
   $ uwsgi --ini uwsgi.ini &