---
prelude: |
    This release of OpenStack Glance introduces 2 new API versions. Images
    API v2.7 adds support and modifications for the Hidden Images and
    Multihash features introduced during Rocky cycle. Version 2.8 is
    included as an optional EXPERIMENTAL API for testing and preparing for
    multiple back-end support.

    Rocky development cycle marks long waited milestone on Glance work. The
    Images API v1 which has been deprecated for years is finally removed and
    not available at all in Glance version 17.0.0 forward.

    Some security aspects were tackled for this release. Multihash, providing
    secure hashing for image data with future proof options marks the end of
    relying upon MD5 checksums when verifying image payloads. OSSN-0075
    migitation lessens the risk of ID reusability on those very rare cases
    when a database purge is necessary.

    When delayed delete is enabled operators are able to recover image records
    if the scrubber has been stopped before the data removal interval. While
    the image metadata is still not preserved in these cases, this provides a
    way to save the image data on accidental deletes.

    Due to increasing core counts on modern servers Glance services started
    consuming huge amounts of resources as the default was to spin up equal
    amount of workers to logical CPUs seen on the host. This automatic scaling
    was capped to 8 workers limiting the resources consumed. While each worker
    can handle a pool of connections this limit should be sufficient for most
    clouds. Large deployments should monitor their performance after upgrade.

    When using Interoperable Image Import workflow, the cloud operators can
    now enable automatic image conversion to desired format. When the plugin
    is enabled end-users do not have any input to its operation but their
    local checksum might not match with checksums recorded in Glance.