title: How to add private registry certs to Docker Machine
body: <p>I upgraded my Mac (OS X) from an older Docker installation to Docker Toolbox, meaning that I'm now working with Docker Machine, and in the process discovered that certs I had working for push/pull with a private registry are not there, and I can't for the life of me figure out how to get them in place. At the moment when I try a test pull I get the dreaded <code>x509: certificate signed by unknown authority</code> error. I've searched around, looked at issues in Github, but nothing has worked for me. I even tried ssh'ing into the machine VM and manually copying them into /etc/ssl/certs, and various other things, with no luck. And I certainly don't want to get into the "insecure-registry" stuff. This used to work with boot2docker prior to moving to docker-machine.</p>
  
  <p>This seems like a very simple question: I have a couple of <code>.crt</code> files that I need put in the right place so that I can do a push/pull. How does one do this? And secondarily, how can this not be documented anywhere? Can we wish for a <code>docker-machine add-cert</code> command someday?</p>
  
  <p>Thanks for any help, and I hope a good answer here can stick around to assist others who run into this.</p>