api_database API database apiv21 API v2.1 authentication authentication availabilityzones availability zones barbican Barbican cells cell cloudpipe cloudpipe configdrive config drive crypto crypto ephemeral_storage_encryption ephemeral storage encryption fping fping hyperv HyperV hypervisor hypervisor ironic bare metal ipv6 IPv6 key_manager key manager libvirt Libvirt livemigration live migration osbrock os-brick pci PCI periodic periodic placement placement quobyte Quobyte USP volume driver rdp RDP rpc_all all RPC serial_console serial console spice SPICE trustedcomputing trusted computing upgrade_levels upgrade levels vnc VNC volumes volumes wsgi WSGI xen Xen xvpvncproxy XCP VNC proxy