Nginx

• Beginner’s Guide

• Some CLI commands:

  • Start nginx sudo nginx (takes config from /etc/nginx/nginx.conf)
  • Manage service : sudo nginx -s [reload|stop|quit]
  • Test config: sudo nginx -t
  • Custom config: sudo nginx -c /custom/config # Couldn’t get this to work

• Config file syntax:

  • Consists of “directives” that are like for eg a “simple” directive: <command> [<key>] <value>;

  • A “block” directive consits of a number of simple directives in braces for eg:

    <block_command> <value> {
      <command1> <value>;
      <command2> <value>;
      <command3> <value>;
    }
    

  • Braces form a “context”, which is similar to a lexical scope of javascript braces

  • And just like javascript global scope, nginx’s is called “main context”.

  • main { events {} http { server { location {} }}}

• Static Serve:

  • Define inside several server (and location) blocks

  • client request -> parse URI -> match longest location string -> append and respond

  • Eg, 2 locations : /data/html /data/images with following config:

    server {
      location / {
        root /data/html;
      }
    
      location /images {
        root /data;
      }
    }
    

  request : localhost/ => matches / => /data/html/index.html request : localhost/images/test.png => matches /images (longest) => /data/images/test.png

  • Regular expression:

    location ~ \.(gif|jpg|png)$ {
      root /data/images;
    }
    

• Proxy:

  • Act as a middleman for requests

  • Client request -> Forward to specific server -> Receive reply from server -> Client response

  • Eg, request come on /proxy-this and need to be sent to a separate server on port 8080, and /proxy-that on port 8081, then config would be:

    server {
        listen 80;
        server_name somedomain.com; # This is optional
        location /proxy-this/ {
          proxy_pass        http://127.0.0.1:8080;
        }
        location /proxy-that/ {
          proxy_pass        http://127.0.0.1:8081;
        }
    }
    

  • Note that the trailing slash in proxy_pass value changes where location is truncated

  • Helpful directives:

    proxy_http_version 1.1;
    proxy_set_header Upgrade $http_upgrade;
    proxy_set_header Connection 'upgrade';
    proxy_set_header Host $host;
    proxy_set_header  X-Real-IP        $remote_addr;
    proxy_set_header  X-Forwarded-For  $proxy_add_x_forwarded_for;
    proxy_cache_bypass $http_upgrade;
    

• Load balancing: This config will start balancing requests on 3 addresses (default round robin)

  http {
    upstream poxy-server {
      server server_addr1;
      server server_addr2;
      server server_addr3;
    }
  
    server {
      location / {
        proxy_pass http://proxy-server;
      }
    }
  }