This is an old post but I had the same problem. So for future:
you need to import the library via bundler
require 'bundler'
Bundler.require 'mysql2'
source: https://stackoverflow.com/questions/21699110/require-cannot-load-such-file-mysql2
This is an old post but I had the same problem. So for future:
you need to import the library via bundler
require 'bundler'
Bundler.require 'mysql2'
source: https://stackoverflow.com/questions/21699110/require-cannot-load-such-file-mysql2