Capistrano task to open a rails console on a remote server. Require this file in your deploy.rb and run "cap rails:console"

rails.rb

# encoding: UTF-8

Capistrano::Configuration.instance(:must_exist).load do
  namespace :rails do
    desc "Open the rails console on one of the remote servers"
    task :console, :roles => :app do
      hostname = find_servers_for_task(current_task).first
      exec "ssh -l #{user} #{hostname} -t 'source ~/.profile && #{current_path}/script/rails c #{rails_env}'"
    end
  end
end

Adapted for Capistrano 3

namespace :rails do
  desc "Open the rails console on one of the remote servers"
  task :console do |current_task|
    on roles(:app) do |server|
      exec %Q[ssh -l #{server.user} #{server.hostname} -p #{server.port || 22} -t 'source ~/.bashrc > /dev/null; cd #{release_path}; bin/rails console']
    end
  end
end