image volume cache internal tenant subject to quotas

[Brian Rosmaita]

Cinder has these 2 options governing the image-volume-cache:

   image_volume_cache_max_size_gb
   image_volume_cache_max_count

The default value for these is 0 (unlimited), but in practice, the number of GB/volumes is subject to the quotas on the internal tenant configured as the cache owner. This confuses some people, and it would be good to make this point explicitly in the documentation.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/cinder/+/903174

[Jeremy Stanley (fungi)]

I've switched this back to a regular public bug. If you actually think a report may represent a vulnerability, please include your rationale for that belief when switching a bug's type to security.

[Brian Rosmaita (brian-rosmaita)]

Thanks, Jeremy. @johnsonjiang, I'm not sure what the vulnerability would be? The point of the documentation request is that even with the default setting of 0 for the image_volume_cache_max options, the cache is actually limited by the quotas that apply to whoever is configured as the internal tenant owning the cache. The issue is that the cache turns out to be smaller than the operator may think, depending on what the quotas are on the internal tenant.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/cinder/+/903174
Committed: https://opendev.org/openstack/cinder/commit/5b59d85dc05457f0cac757ae32dbce35b368955d
Submitter: "Zuul (22348)"
Branch: master

commit 5b59d85dc05457f0cac757ae32dbce35b368955d
Author: Brian Rosmaita <email address hidden>
Date: Fri Dec 8 09:16:23 2023 -0500

    [docs] quotas apply to image-volume-cache owner

    Add a note that even though there are configuration options
    governing the number and total GB consumed by volumes in the
    image-volume-cache, the internal tenant configured as the
    cache owner is nonetheless subject to quotas, which can affect
    the actual amount of stuff cached.

    Change-Id: Ice12d2f7401fa481bb410c7518bfc436d90bb86a
    Closes-bug: #2045984

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/cinder 24.0.0.0rc1 release candidate.