Scripting Nginx with LUA

Hiroshi Miura @miurahr

Nginx

Nginx

nginx.org

• High performance

• Asynchronous architecture, event driven

• Low memory foot print

• Declarative configuration syntax

• Extesible architecture with module

OpenResty

OpenResty.org

• OpenResty: Nginx + module collection

• Non-Blocking I/O with Nginx and modules

• memcached

• redis

• PostgreSQL

• MySQL

• Lua embeded scripting engine as nginx module.

• Collection of Lua resty libraries

• In production on Alibaba group, world largest EC site.

Nginx Config(1)

  server {
listen 80;
listen [::]:80 default_server;

root /usr/share/nginx/html;
index index.html index.htm;

server_name localhost;

Nginx Config(2)

location / {
    # First attempt to serve request as file, then
    # as directory, then fall back to displaying a 404.
    try_files $uri $uri/ /index.html;
}

location /doc/ {
    alias /usr/share/doc/;
    autoindex on;
    allow 127.0.0.1;
    deny all;
}

Non blocking I/O with Nginx

Use memcached with nginx and module.

  location /memcached {
    set $memc_cmd $arg_cmd;
    set $memc_key $arg_key;
    set $memc_value $arg_val;
    set $memc_exptime $arg_exptime;
    memc_pass 127.0.0.1:11211;
  }

Lua

Lua

lua.org

• Scripting language born in Brazil in 1992

• Combines simple procedural syntax with powerful data description

  • Dynamic variable type

  • Register-based virtual machine

  • Automatic memory management

Lua

• "Lua" (pronounced LOO-ah) means "Moon" in Portuguese

Why Lua

• Lua is a proven, robust language

• Lua is fast

• Lua is portable

• Lua is embeddable

• Lua is powerful

• Lua is small

• Lua is free

• Lua loves Games

Lua Nginx Module

• Provide directives to run Lua scripts during Nginx processes

  • Rewrite phase
  • Access phase
  • Content phase
  • Log phase

• Access Nginx environment from Lua scripts

• Very fast as Nginx does

• Faster with Lua JIT

• github.com/chaoslawful/lua-nginx-module

Hello, Lua

location /hellolua {
    default_type 'text/plain';

    content_by_lua '
       local name = ngx.var.arg_name or "Anonymous"
        ngx.say("Hello, ", name, "!")
    ';
}

$ curl http://localhost/hellolua?name=Lua
Hello, Lua! 

Load Lua files

Modules are loaded once, on the first request

location /lua {
    rewrite_by_lua_file /path/to/rewrite.lua;
    access_by_lua_file /path/to/access.lua;
    content_by_lua_file /path/to/content.lua;
}

Lua Nginx API

• Coroutine to integrate with nginx reactor

• Synchronous interface to access non-blocking I/O API.

  • Access HTTP request
  • Compose HTTP response
  • Perfome sub-request to locations
  • Connect to other (upstream) network services

CoSocket

Non-blocking networking I/O with "Cosocket"

• Send and recieve TCP/UDP on Inet/Unix domain socket.

• Compatible with Lua socket API

• Keepalive mechanism to pool connections

Cosocket example

location /memcached {
    content_by_lua '
        local sock = ngx.socket.connect("127.0.0.1", 11211)
        sock:send("SET foo bar 3600\r\n")
        local line = sock:receive()
        if line then
            ngx.say(line)
        end
        sock:setkeepalive()    ';
}

$ curl http://localhost/memcached
STORED

Synchnonization support

context data

Per-request context data = Lua table to store data duraring request lifetime

 location /ctx {
  access_by_lua '
    ngx.ctx.userid = 'abcde'
  ';
  content_by_lua '
    ngx.say(ngx.ctx.userid)
  ';
 }
 $ curl http://localhost/ctx
abcde

Shared dictionary

Global hash table across all requests

http {
    lua_shared_dict stats 10m;
    server {
        location / {
            content_by_lua '
               ngx.shared.stats:incr("hits", 1)
               ngx.say(ngx.shared.stats:get("hits"))
            ';
        }
    }
}

Lua-resty-* family

• OpenResty bundles Lua modules selection

• Providing APIs for popular services

  • lua-resty-memcached
  • lua-resty-redis
  • lua-resty-mysql

lua-resty-memcached

location /memcached {
    content_by_lua '
        local memcached = require "resty.memcached"
        local memc = memcached:new()
        local ok, err = memc:connect("127.0.0.1", 11211)

        local ok, err = memc:set("foo", "bar", 3600)
        if ok then
            ngx.say("STORED")
        end

        memc:set_keepalive()    ';
}

Use Case

• URL shorten service

• RESTful API services

• API translation and authentication service

• Caching improvement

• A/B testing

• Inteligent content delivery

Use Case

Build Tile serving service - TileMan

Credit

• OpenResty is maintained by agentzh, chaoslawful etc.

• I borrowed some example and ideas from @agentzh, James Hurst @pintsized.

• This presentation is written by Markdown2Impress.

Questions?

introduction to OpenResty