---
prelude: >
  This was a quiet development cycle for the ``glance_store`` library.
  One new feature was added to the Swift store driver.  Several bugs
  were fixed and some code changes were committed to increase stability.
features:
  - |
    A `BufferedReader`_ has been added to the Swift store driver in
    order to enable better recovery from errors during uploads of large
    image files.  Because this reader buffers image data, it could
    cause Glance to use a much larger amount of disk space, and so the
    Buffered Reader is *not* enabled by default.

    To use the new reader with the Swift store, you must do the following:

    * Set the ``glance_store`` configuration option ``swift_buffer_on_upload``
      to ``True``

    * Set the ``glance_store`` configuration option ``swift_upload_buffer_dir``
      to a string value representing an absolute directory path.  This
      directory will be used to hold the buffered data.

    The Buffered Reader works by taking advantage of the way Swift stores
    large objects by segmenting them into discrete chunks.  Thus, the amount
    of disk space a Glance API node will require for buffering is a function
    of the ``swift_store_large_object_chunk_size`` setting and the number of
    worker threads (configured in **glance-api.conf** as the value of
    ``workers``).  Disk utilization will cap at the following value

    swift_store_large_object_chunk_size * workers * 1000

    Be aware that depending upon how the file system is configured, the disk
    space used for buffering may decrease the actual disk space available for
    the Glance image cache, which may affect overall performance.

    For more information, see the `Buffered Reader for Swift Driver`_ spec.

    .. _BufferedReader: http://git.openstack.org/cgit/openstack/glance_store/commit/?id=2e0024c85ca2ddf380014e44213be4fb876f680e
    .. _Buffered Reader for Swift Driver: http://specs.openstack.org/openstack/glance-specs/specs/mitaka/approved/buffered-reader-for-swift-driver.html
fixes:
  - |
    * Bug 1738331_: Fix BufferedReader writing zero size chunks
    * Bug 1733502_: Use cached auth_ref instead of getting a new one each time

    .. _1738331: https://code.launchpad.net/bugs/1738331
    .. _1733502: https://code.launchpad.net/bugs/1733502
upgrade:
  - |
    Two new configuration options, ``swift_buffer_on_upload`` and
    ``swift_upload_buffer_dir`` have been introduced.  These apply only to
    users of the Swift store and their use is optional.  See the New Features
    section for more information.