OpenStack
To add an OpenStack cloud you'll need your username, password, Auth URL and your Tenant name. You can optionally specify a Region and the Compute Endpoint.
The first thing you should do is click " Add cloud" and select "OpenStack" from the providers' list.
Required fields here are your Username, Password, Auth URL and Tenant Name. The Auth URL might be the base url (e.g. https://192.168.1.101:5000) or a full path (e.g.https://192.168.1.101:5000/v2.0/)
Optional field is the Region name, you should set this if you've specified another Region than the default RegionOne.
You can also specify the compute endpoint. In most cases this is not needed and auth_url is enough, however depending on the way the OpenStack has been set, the service catalog might return private ips thus mist.io won't be able to connect. If that's the case, by providing the public ip of the compute endpoint we can make the connection. Note the URL, this should be something like http://212.44.45.234:8774/v2.1
Once you click on Add, Mist.io will try to authenticate with OpenStack. If all goes well, you should see a list of your VMs in the Machines section.