Capistrano recipes for SSHing into multiple servers simultaneously using csshX. Ensures csshX is installed if you're using homebrew on OSX. Add this or load it into your deploy.rb and profit.

csshx.rb

namespace :csshx do
  task :install do
    `which csshx`
    if $? != 0
      Bundler.with_clean_env do
        run_locally 'brew install csshx'
      end
    end
  end

  desc "SSH into all app servers"
  task :app_servers, roles: :app do
    invoke_csshx
  end

  desc "SSH into all worker servers"
  task :worker_servers, roles: :worker do
    invoke_csshx
  end
end

def invoke_csshx
  csshx.install
  servers = find_servers_for_task(current_task).map { |s| "#{user}@#{s.host}" }.join(' ')
  run_locally "csshx #{servers}"
end

This also works with multistage environments since the servers are determined via your Capistrano config, e.g.:

cap production csshx:app_servers
cap staging csshx:worker_servers