title: How to run AWS instances with attached ephemeral disks with the fog library
body: <p>I would like to know if there is an equivalent option of "--block-device-mapping" in <code>ec2-run-instances</code> command line to attach ephemeral disks on AWS instances with the fog library.</p>
  
  <p>There is a reference on <code>BlockDeviceMappings</code> in the fog source code. But since the documentation is a bit terse and I'm not a ruby expert, any help will be welcome!</p>