我可以ssh到OpenStack实例，但Ansible不能 - 它有什么不同的做法？

I've created an Ubuntu instance in OpenStack and retrieved the pem file to allow me to ssh into it from my Control machine. In total I have just two machines: My Control machine running Ubuntu and with Ansible 2.0.0.2 installed, and my Openstack instance that is also running Ubuntu.I've created an Ubuntu instance in OpenStack an