openresty-statsd

A Lua module for openresty to send metrics to StatsD

Features

• increments!
• counts!
• timers!
• cosocket frolics
• batchin'

Installation

1. Install openresty configured --with-luajit
2. Copy lib/statsd.lua somewhere that openresty nginx can find (you may need to adjust your LUA_PATH or use lua_package_path directive
3. Configure nginx:

    # an nginx conf
    http {
      -- optionally set relative lua_package_path
      lua_package_path "${prefix}lua/*.lua";
      
      -- make the statsd variable available in each phase
      init_by_lua 'statsd = require("statsd")';

      location /some_location {
        content_by_lua '
          -- this is the phase where metrics are sent
          -- batch metrics into packets of at least 50
          if table.getn(statsd.buffer) > 50 then statsd.flush(ngx.socket.udp, "127.0.0.1", 8125) end
        ';
        
        log_by_lua '
          -- this is the phase where metrics are registered
          statsd.incr("test.status." .. ngx.var.status)
          statsd.time("test.req_time", ngx.now() - ngx.req.start_time())
        ';
      }
    }

The request-response lifecycle in nginx has eight phases. The data you are likely to want to report (HTTP status, request time) is available in the last phase, log, but the socket API is not available. That's why stats are registered in log_by_lua and sent via flush in content_by_lua.

Changelog

• 0.0.1: Works. Tested.

Development

Prerequisites for dev and testing

• http://openresty.org/#Installation
• https://github.com/etsy/statsd#installation-and-configuration
• ruby, rubygems, bundler
• luarocks

Build

1. Clone the repo
2. bundle
3. rake openresty:install
4. rake statsd:install
5. luarocks install busted [--local]
6. Add lib/?.lua to your LUA_PATH

guard will run the unit tests.

foreman start will spin up nginx and statsd using dev configuration from ./config and ./examples.

Related projects

• lua-statsd - doesn't use openresty's cosockets
• nginx-statsd - written in C
• fozzie - our Ruby StatsD client

Author

Dave Nolan / lonelyplanet.com