How to use any gem in the Rails production console

How many times did you come across a great gem you wanted to try out in a production console, like benchmark-ips opens a new window or awesome-print opens a new window ?

Be it for performance or for readability, sometimes it’s nice to be able to try out something new quickly without going through a pull request + deployment process. This is possible by modifying the $LOAD_PATH opens a new window Ruby global variable and requiring the gem manually.

The Ruby global variable $LOAD_PATH is an alias for $:, which essentially contains an array of paths that your app will search through when using the Kernel method require.

Obviously the real solution here would be to just put the gem in your Gemfile, and bundle. However, if you wish to use benchmark-ips to test the performance of methods in a Rails console with production data and you don’t have the gem already bundled, then follow these steps:

  • SSH into your target server
  • Run gem install benchmark-ips
  • Run gem env gemdir to figure out the path where gems are installed. For example:
  • Open the Rails console
  • Add the gem’s path to the $LOAD_PATH global variable, like so:
$LOAD_PATH << "/usr/local/rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/benchmark-ips-2.7.2/lib"
  • Finally, require the gem’s entry point file. You may need to look into the gem’s structure to figure out what file you need to require. For example, for benchmark-ips:
require "/usr/local/rbenv/versions/2.1.2/lib/ruby/gems/benchmark-ips-2.7.2/lib/benchmark/ips.rb"

This should let you use almost any gem you need in a Rails production console.