# File lib/deltacloud/drivers/ec2/ec2_driver.rb, line 239
        def run_on_instance(credentials, opts={})
          target = instance(credentials, :id => opts[:id])
          param = {}
          param[:credentials] = {
            :username => 'root', # Default for EC2 Linux instances
          }
          param[:port] = opts[:port] || '22'
          param[:ip] = target.public_addresses
          param[:private_key] = (opts[:private_key].length > 1) ? opts[:private_key] : nil
          safely do
            Deltacloud::Runner.execute(opts[:cmd], param)
          end
        end