RequestId

application.rb

# http://stackoverflow.com/a/9380164/1171712
module MyFancyApp
  class Application < Rails::Application
    config.log_tags = [:uuid, :remote_ip]
  end
end

client.rb

# https://github.com/yourkarma/faraday-conductivity

require "faraday/conductivity"

connection = Faraday.new(url: "http://widgets.yourapp.com") do |faraday|
  faraday.request :request_id
  faraday.adapter Faraday.default_adapter
end

nginx.conf

# http://stackoverflow.com/questions/17748735/setting-a-trace-id-in-nginx-load-balancer
# http://ryandlane.com/blog/2014/12/11/using-lua-in-nginx-for-unique-request-ids-and-millisecond-times-in-logs/
# https://gist.github.com/oroce/957791561e26738bf941

http {
  server {
    set $reqid $pid-$msec-$remote_addr-$request_length-$connection;
    if ($http_x_request_id != '') {
      set $reqid $http_x_request_id;
    }
    location / {
        proxy_pass  http://upstream;
        proxy_set_header X-Request-Id $reqid;
    }
}