basic nginx conf for continuous experimentation

splitter example conf

upstream _a {
    server 127.0.0.1:8000;
}

upstream _b {
    server 127.0.0.1:8001;
}

upstream _c {
    server 127.0.0.1:8002;
}

# Chain of upstream conditions
# ----------------------------
# In order of preference, set upstream by:
# - url parameter
# - cookie
# - random

split_clients $date_gmt $random_splitter {
    10% _a;
    10% _b;
    80% _c;
}

map $cookie__v $cookie_upstream {
    '_a' _a;
    '_b' _b;
    '_c' _c;
    default $random_splitter;
}

map $arg__v $upstream {
    '_a' _a;
    '_b' _b;
    '_c' _c;
    default $cookie_upstream;
}

# EOF of upstream conditions

server {

    listen 80;
    server_name localhost;

    location / {
        proxy_pass http://$upstream$request_uri;
        proxy_pass_request_headers on;
        proxy_set_header Host $host;
        add_header X-Time $date_gmt;
        proxy_set_header X-Time $date_gmt;
    }
}

splitter.rb

# Cookbook: splitter
# Recipe: splitter::nginx
# Author: Dave Nolan <dave.nolan@lonelyplanet.com>
# Description: Configure nginx to act as an a/b splitting load balancer

include_recipe 'nginx::default'
include_recipe 'nginx::ohai_plugin'
# FIXME: include_recipe 'nginx::http_stub_status_module'

include_recipe 'splitter::default'

configuration = Splitter::Configuration.new(data_bag_item('variants', node[:project]))

template "splitter" do
  path "#{node['nginx']['dir']}/conf.d/splitter.conf"
  source "nginx.conf.erb"
  owner "root"
  group "root"
  mode "0644"
  variables(
            "configuration"  => configuration,
            "server_name"    => node[:splitter][:server_name],
            "split_strategy" => node[:splitter][:strategy]
  )

  notifies :reload, resources(:service => "nginx")
end

Hey there TextGoesHere,

How did this end up working out for you? I'm doing something similar. I like the date_gmt touch!

-JB

On a strange side note, looks like you work/worked for Lonely Planet which my current company, Tobi.com shares a building with in Oakland, CA. Anyhoo...

Hey, works out great. Essentially the same code powers A/B tests here today.

Hah, small world! I'm actually based in London, UK. We're now also building a tech team in Franklin, TN if you're interested... http://www.lonelyplanet.com/jobs/