Chef-Metal and encrypted ssh keys

I’m trying to start instances with chef-metal and encrypted ssh keys.

I’m getting this:

“Could not parse PKey: no start line”

Since the documentation for chef-metal is so bad, I’ve had to dig through
the fog documentation in order to try and work out what magic combination
of options to use with chef-metal.

I think chef-metal thinks the key is not encrypted. How do I tell
chef-metal that it is encrypted?