---
features:
  - |
    With the introduction of the Glance multiple stores feature, introduced
    on an experimental basis in Rocky and now established as a full feature
    in the Train release, it is now possible for Glance to use backends
    accessed via the glance_store library for the temporary storage of
    data that previously required access to the local filesystem.  Please
    note the following:

    * In this release, the use of stores (instead of local directories) is
      optional, but it will become mandatory for the 'U' release.

    * In this release, the stores used *must* be the filesystem store type.
      Our goal is that in a future release, operators will be able to
      configure a store of their choice for these functions.  In Train,
      however, each of these *must* be a filesystem store.

    Please see the Upgrades section of this document and the "Multi Store
    Support" chapter of the Glance Administration Guide for more information.

upgrade:
  - |
    The configuration options ``work_dir`` and ``node_staging_uri`` are
    deprecated and will be removed early in the 'U' development cycle.

    These local directories are used by Glance for the temporary storage
    of data during the interoperable image import process and by the
    tasks engine.  This release introduces the ability to instead use a
    backend filesystem store accessed via the glance_store library for this
    temporary storage.  Please note the following:

    * If you wish to use the backend store feature now, please see the
      "Reserved Stores" section of the "Multi Store Support" chapter of
      the Glance Administration Guide for configuration information.

    * If you use the Glance multiple stores feature, introduced on an
      experimental basis in Rocky and now fully supported in the Train
      release, then you *must* use backing stores instead of ``work_dir``
      and ``node_staging_uri`` for Glance's temporary storage **beginning
      right now with the current release**.  See the "Reserved Stores"
      section of the "Multi Store Support" chapter of the Glance
      Administration Guide for more information.

  - |
    The store name prefix ``os_glance_*`` is reserved by Glance for internal
    stores.  Glance will refuse to start if a store with this prefix is
    included in the ``enabled_backends`` option.

    The internal store identifiers introduced in this release are
    ``os_glance_tasks_store`` and ``os_glance_staging_store``.

issues:
  - |
    When using the multiple stores feature, each filesystem store **must**
    be configured with a different value for the ``filesystem_store_datadir``
    option.  This is not currently enforced in the code.