---
features:
  - |
    The 2.32 microversion adds support for virtual device
    role tagging. Device role tagging is an answer to the
    question 'Which device is which, inside the guest?' When
    booting an instance, an optional arbitrary 'tag'
    parameter can be set on virtual network interfaces
    and/or block device mappings. This tag is exposed to the
    instance through the metadata API and on the config
    drive. Each tagged virtual network interface is listed
    along with information about the virtual hardware, such
    as bus type (ex: PCI), bus address (ex: 0000:00:02.0),
    and MAC address. For tagged block devices, the exposed
    hardware metadata includes the bus (ex: SCSI), bus
    address (ex: 1:0:2:0) and serial number.

    The 2.32 microversion also adds the 2016-06-30 version
    to the metadata API. Starting with 2016-06-30, the
    metadata contains a 'devices' sections which lists any
    devices that are tagged as described in the previous
    paragraph, along with their hardware metadata.
issues:
  - When using virtual device role tagging, the metadata on
    the config drive lags behind the metadata obtained from
    the metadata API. For example, if a tagged virtual
    network interface is detached from the instance, its tag
    remains in the metadata on the config drive. This is due
    to the nature of the config drive, which, once written,
    cannot be easily updated by Nova.
