glance/releasenotes/notes/rethinking-filesystem-access-120bc46064b3d40a.yaml
Abhishek Kekane 6dba83ba3a Rethinking filesystem access
In Rocky multiple backend support is added as experimental feature. In
order to take advantage of this feature it is decided to deprecate
work_dir and node_staging_uri configuration options
and reserve two filesystem stores 'os_glance_tasks_store' and
'os_glance_staging_store', which can be used to get rid of initializing
store via internal functions.

These internal stores are considered "reserved stores" by Glance.
For the time being, these are hard-coded as filesystem stores.  The
store prefix 'os_glance_' is reserved for internal Glance use and
the glance-api service will refuse to start if a store with this
prefix is included in the enabled_backends config option in
glance-api.conf.

NOTE: Because there are no sensible default values for the location
of the datadir for each of these stores, the operator must define
'os_glance_tasks_store' and 'os_glance_staging_store' in
glance-api.conf configuration file as shown below.

[os_glance_tasks_store]
filesystem_store_datadir = /var/lib/glance/tasks_work_dir/

[os_glance_staging_store]
filesystem_store_datadir = /var/lib/glance/staging/

Each filesystem store must have a unique datadir.

Depends-On: https://review.openstack.org/#/c/639765/
Implements: blueprint rethinking-filesystem-access
Change-Id: I86ec513c5fc653dbb97b79d953d8430f014e684f
2019-10-01 09:53:48 +00:00

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2.7 KiB
YAML

---
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.