image-volume-cache options incorrectly default to None and prevent startup

[Trent Lloyd]

The following image-volume-cache options get written to the configuration file with a value of "None" by default which fails to parse and cinder-volume won't start.

image_volume_cache_max_size_gb = None
image_volume_cache_max_count = None

= Error Message =

2022-04-12 05:41:34.758 1194037 ERROR cinder.cmd.volume [req-UUID - - - - -] Volume service cinder-volume@cinder-purestorage failed to start.: oslo_config.cfg.ConfigFileValueError: Value for option image_volume_cache_max_size_gb from LocationInfo(location=<Locations.user: (4, True)>, detail='/etc/cinder/cinder.conf') is not valid: invalid literal for int() with base 10: 'None'
2022-04-12 05:41:34.758 1194037 ERROR cinder.cmd.volume ValueError: invalid literal for int() with base 10: 'None'

= Cause =

This occurs because the config.yaml defaults are Null and config.get returns a value of "None" in such a case.

In most cases this pattenr works because values are only rendered in a template if they pass an "if VARIABLE_NAME" test which fails if it is None. However in this case the values are sent via relation to charm-cinder which then iterates on the list and renders them directly to the file without checking for a value of None.

= Workaround =

You can explicitly configure the values to 0 (which is the upstream default) to workaround the issue:

juju config cinder-purestorage image-volume-cache-max-count=0 image-volume-cache-max-size-gb=0

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/charm-cinder-purestorage/+/844256

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/openstack/charm-cinder-purestorage/+/844256
Committed: https://opendev.org/openstack/charm-cinder-purestorage/commit/b3a5d3b35835d454224e5404b41a548f52322bed
Submitter: "Zuul (22348)"
Branch: master

commit b3a5d3b35835d454224e5404b41a548f52322bed
Author: Trent Lloyd <email address hidden>
Date: Wed Jun 1 15:46:39 2022 +0800

    Fix image-volume-cache configuration defaults

    The image_volume_cache_max_count and image_volume_cache_max_size_gb
    options were incorrectly being written to cinder.conf with a value of
    "None" when not configured.

    This occurred because config.get returns None for values with a null
    default, this value was being placed into a dictionary and sent over
    relation data to charm-cinder which renders it directly from a list of
    key-value pairs.

    Fix the handling of these options not to include them in the dictionary
    if they are None.

    Closes-Bug: #1976465
    Change-Id: I61781fa5d837d0ed5191d8a92cc8e0bdf600c08a

[Trent Lloyd (lathiat)]

This fix has been cloned into all branches from stable/train through stable/zed (as well as master).

CharmHub migration seems complete for the charm but it has not yet been tested and released into a channel-per-release. That work is pending.

[Trent Lloyd (lathiat)]

This has now been released to the edge channel for all releases back to ussuri.