Created for handling 10k of concurrent connections with the focus on

• High Performance
• High Concurrency
• Low Resource Usage

Official Definition NGINX is open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers.

Nginx vs Apache

The main difference between Apache and NGINX lies in their design architecture. Apache uses a process-driven approach and creates a new thread for each request. Whereas NGINX uses an event-driven architecture to handle multiple requests within one thread.

Nginx Features

• Event-driven
• Asynchronous
• Non-blocking

Result

• Faster Static Resources
• High Concurrency

Configuration

Two main configuration terms are context and directive.

• Directive is a spesific configuration includes a name and a value
• Context is section within the configuration. Its like a scope. Context are nested and inherited from the parent.

Creating a Virtual Host

It's gonna serve static files from a directory on your server. Let's say that we have an html, css and a png file.

• nginx.conf file is located /etc/nginx.

The default conf looks like this

user  nginx;
worker_processes  auto;

error_log  /var/log/nginx/error.log notice;
pid        /var/run/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
                      '$status $body_bytes_sent "$http_referer" '
                      '"$http_user_agent" "$http_x_forwarded_for"';

    access_log  /var/log/nginx/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    keepalive_timeout  65;

    #gzip  on;

    include /etc/nginx/conf.d/*.conf;
}

In order to define a virtual host we need at least these configs

events {}

http {

}

• First, we define server context or server block.
• It essentially will listen on port 80
• Next we set the server_name which is the domain, subdomain or an ip address for which the server context exists.
• Finally define a root directive. This will be the root path from which nginx will be serving requests or interpreting static requests from.

events {}

http {

  server {

    listen 80;
    server_name 167.99.93.26;

    root /sites/demo;
  }
}

When we first reload this configs we can't see the css in browsers. When we check the browser the style file loaded.
So, what is the problem?

Nginx is sending the wrong mime type with the stylesheet. We can confirm this by requesting the style.css.
When we write `curl -I http://167.99.93.26/style.css`, we can see that Content-Type: text/plain.
To fix that we can provide content type in the conf file. But there is another way to do that. mime.types are located in etc/nginx folder. We simply include it.

events {}

http {

  include mime.types;

  server {

    listen 80;
    server_name 167.99.93.26;

    root /sites/demo;
  }
}

Location Blocks

The most used context in any nginx configuration. Think of location as intercepting a request based on its value and then doing something other than just trying to serve a matching file relative to the root directory as we saw in the previous.
The standard behavior is great for static resources. But if we request something like domain/greet, domain/users and etc., nginx can not match a file and instead serves default 404 page.

Location context takes paremeter uri. ``` location /greet{ return 200 'Hello from NGINX "/greet" location.'; } ```

There are several ways to match uri in location blocks.

• Prefix match => anything started with /greet will match. For ex /greetings, /greet/user
• Exact match => location = /greet
• Regex match => location ~/greet[0-9], /greet will not match. /greet1 will match. Note that ~ is case sensitive.
• Regex case insensitive => location ~* /greet[0-9]
• Preferential prefix match => location ^~ /greet. Same as prefix but more important than regex.

There is priority in these matches. For ex: regex is prior from prefix. The order is like that : exact -> preferential -> regex -> prefix

Variables

Nginx has variables and we can also define custom variables as well.

set $mon 'No';

    # Check if weekend
    if ( $date_local ~ 'Monday' ) {
      set $mon 'Yes';
    }

We can also use statements.

if ($request_method = POST ) {
  return 405;
}

It is generally considered as a good idea to avoid using if. https://www.nginx.com/resources/wiki/start/topics/depth/ifisevil/

Rewrites and Redirects

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