With em-proxy, a proxy built with eventmachine, you can send some real traffic to your Engine Yard Cloud environment for load testing. This allows you to test your application’s performance prior to migrating giving you peace of mind that things will perform great once you do migrate. It will also allow you to compare your New Relic stats and make any needed adjustments.
WARNING! Because you will be sending real traffic to Engine Yard Cloud using this technique, you need to be absolutely sure to disable things like email and billing in your application while you test. You do not want to be double billing or spamming your users.
Using this example configuration, requests returning from Engine Yard Cloud will be dropped at the proxy. This will make your testing completely transparent to your end users.
Configuration and installation
You perform the proxy setup and configuration on your current production servers. It resides between your load balancer and your web server. As a few adjustments will need to be made, we’ll describe those in detail in a moment.
Install the gem and create your configuration file
sudo gem install em-proxy --no-ri --no-rdoc
Create a proxy.rb file to the root users home directory.
Since em-proxy will be running on port 80, nginx will have to run on port 8080. Change your nginx vhost listening on port 80 to port 8080, then restart nginx using /etc/init.d/nginx restart command.
Start the proxy
Start the proxy up on one server at a time, if you run into issues along the way it will be much easier to back out any changes.
Run the proxy.rb inside of a screen session.
$ screen $ ruby proxy.rb
To detach from the screen session simply hit ctrl+a+d and you will detach.
To later resume the screen session:
The proxy will start up and start taking traffic on port 80. It will proxy traffic to nginx, locally, on port 8080
Test the setup
Make sure you can curl your app and receive the response you expect.
$ curl -H host:yourhostname.com http://localhost
Disable the proxy
To turn the proxy off
Kill the Ruby process you fired up.
Revert the nginx config changes so that your vhosts are listening on port 80 instead of port 8080.
Restart Nginx using the command: /etc/init.d/nginx restart
Now you are back to your default configuration.
An example of proxy.rb
`#` proxy.rb require 'em-proxy'
Proxy.start(:host => "0.0.0.0", :port => 80) do |conn| conn.server :production, :host => '127.0.0.1', :port => 8080 conn.server :ey_cloud, :host => '22.214.171.124', :port => 80 conn.on_data do |data| data end conn.on_response do |server, resp| resp if server == :production end end
Let’s step through this script and describe what it does.
This starts the proxy up on port 80, and listens for any incoming requests.
Proxy.start(:host => “0.0.0.0”, :port => 80) do |conn|
This proxies the traffic to the servers you define. Your production server proxies locally to nginx and listens on port 8080. NOTE: Replace 126.96.36.199 with the IP of your Engine Yard Cloud environment.