The basics

The basic usage of nginx is to make the reverse proxy to your application. Nginx listen to port 80 waiting for requests and manage the connections, passing the requests to your upstream application server.

server {
    server_name www.yoursite.com;
    listen 80;
    location / {
        proxy_pass http://localhost:8080;
    }
}

The proxy_pass directive proxy the request as HTTP to your application listening port 8080.

You can use uwsgi_pass to make nginx convert the HTTP to a WSGI request and send it to your WSGI application.

server {
    server_name www.yoursite.com;
    listen 80;
    location / {
        include uwsgi_params;
        uwsgi_pass localhost:8080;
    }
}

Most features work for HTTP and uWSGI proxy, with some small configuration changes.

SSL Termination

Nginx terminate the SSL connection and send it to your application as plain HTTP.

ssl_certificate /opt/ssl/www.yoursite.com.crt;
ssl_certificate_key /opt/ssl/www.yoursite.com.key;
server {
    server_name www.yoursite.com;
    listen 443 ssl;
    location / {
        proxy_pass http://localhost:8080;
    }
}

If you want a HTTPS only website, add another server block to redirect the HTTP traffic to HTTPS.

server {
    listen 80;
    server_name www.yoursite.com;
    return 301 https://$host$request_uri;
}

Static files

Nginx serve some thousands of static files per second, without hiccups. Do not make your application serve static files, like images and javascripts. Your application is slow, maybe it'll re-render the same asset for each request.

server {
    server_name www.yoursite.com;
    listen 80;
    root /some/path;
    location /static/ {
        try_files /generated/$uri /cache/$uri @myapp;
    }
    location / {
        try_files $uri @myapp;
    }
    location @myapp {
        include uwsgi_params;
        uwsgi_pass localhost:8080;
    }
}

The try_files directive in /static/ block will check /some/path/generated/static/ and /some/path/cache/static/ for your requested file and if it does not exist, send the request to your application.

You can change the last try_files parameter with =404 to answer with a 404 instead of pass the request to application.

Load balancing

If you want a high available application, nginx can be your load balancer to distribute the load and handle gracefully server failures.

upstream yourapp {
    server http://localhost:8080 weight=5;
    server http://localhost:8081;
    server http://example.com:8080 backup;
}
server {
    server_name www.yoursite.com;
    listen 80;
    location / {
        proxy_pass yourapp;
    }
}

Nginx send the request to your yourapp upstream, choosing one server in a weighted round robin way. 5 requests to the first server, 1 request to the second server and so on. If your servers are down, it sends the request to your backup server.

If one server fail to answer or give an HTTP error, nginx send the request to the next server. No additional configuration needed.

Caching

Some pages are almost static and you don't want it rendering all the time. Nginx can help you serving this content. Configure nginx to cache the page for 10 minutes.

uwsgi_cache_path /tmp/myapp/content/ keys_zone=myapp-content:10m
                 loader_threshold=300 loader_files=200 max_size=100m levels=1:2;
uwsgi_cache_valid 200 301 302 404 10m;
uwsgi_cache_key $host$request_uri;

server {
    server_name www.yoursite.com;
    listen 80;
    location /content/ {
        uwsgi_cache yourcache;
        uwsgi_ignore_headers Set-Cookie;
        uwsgi_hide_header Set-Cookie;
        add_header X-Cache $upstream_cache_status;
        include uwsgi_params;
        uwsgi_pass localhost:8080;
    }
    location / {
        include uwsgi_params;
        uwsgi_pass localhost:8080;
    }
}

Dynamic upstreams

The commercial subscription has this feature built-in, but you probably don't want one. It costs some thousand dollars per server.

The simple way to do it is update the configuration file, adding/removing upstream servers. The nginx reload command update the configuration without downtime.

Conclusion

These snippets are just the basics. Use it to understand how it can help you, but check the docs to learn all the features. Nginx is really powerful and can help you to simplify and improve your system architecture.

Feel free to contact me if you want some help setting up your nginx server. I'm not a system administrator, but I learnt some things about it.