title: Vagrant + Puppet: Unable to run composer install with private repository
body: <p>I'm in the process of setting up Vagrant+Puppet for a project at work. We use <a href="http://getcomposer.org/" rel="nofollow">Composer</a> to manage all of our dependencies. One project has a dependancy that we created that's stored on a private GitHub repository.</p>
  
  <p>I've got everything else set up with Vagrant &amp; Puppet. It installs the proper version of PHP, downloads and installs Composer, and attempts to run Composer. I say 'attempts', because the "composer install" step never works -- we have to use 'vagrant ssh' to get into the machine after it's provisioned and run "composer install" ourselves.</p>
  
  <p>I've got SSH agent forwarding turned on in the Vagrantfile.</p>
  
  <p>Is there something special I need to do to have Puppet run as a user that has access to the SSH key required to clone the GitHub repository? I'd rather not have Vagrant copy the key into the VM ( or mount a specific directory ) because that might not work across all host OSes ( we do have a few people who develop on a Windows machine, and "~/.ssh" won't work there -- I think ). </p>
  
  <p>Any thoughts on how I can resolve this issue?</p>