Modified version of tpol's script. Uses mysql2 gem.

connect.rb

#!/usr/bin/ruby

# gem install mysql2 -v 0.3.12b6

require 'rubygems'
require 'json'
#require 'mysql'
require 'mysql2'

def usage
  puts "USAGE: connect.rb <connections> [<runtime>]"
  exit
end

usage unless ARGV.length >= 1
connections, runtime = ARGV
runtime = runtime.nil? ? 100 : runtime.to_i

conn_arry = []

node = JSON.parse(IO.read('/etc/chef/dna.json'))
database = node['engineyard']['environment']['apps'].first['database_name']
db_pass = node['engineyard']['environment']['ssh_password']
db_user = node['users'].first['username']
db_host = node['db_host']
# override db_host to reference first replica
db_host = node['db_slaves'].first

(1..connections.to_i).each do |n|
  begin
    conn_arry[n - 1] = Mysql2::Client.new( :host => db_host, :username => db_user, :password => db_pass, :database => database)
    puts "Progress: #{n} connections" if n % 2000 == 0
  rescue Exception => e
    puts e.message
    break
  end
end
puts "Reached #{conn_arry.length} of #{connections}"
sleep (runtime)