How to clone existing and configured VMs?
The simplest way is to create the snapshot of your machine from action menu of „instances”.
Once the snapshot is ready, you may see it on „images” page of Horizon.
Go to „instances” menu and launch new instance, exactly the same, as while creating new machine from public template image, but chose as the source „boot from image” (with or without volume creation) and select your snapshot as the source image – it is listed at the end, after all public images. The new machine must have its parameters (flavour, size), at least the same as the original one.
The new machine gets configured as a clone of the original one, except of network addresses (esp. new floating-ip must be associated) and network policies.
Caution: if the original machine had any additional volumes attached to it, they will also be cloned.