"idle_timeout" is missing a help string

[Takashi Natsume]

When executing 'tox -e genconfig', the following warning is emitted.

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stack@devstack-master:/tmp/nova$ tox -e genconfig
genconfig create: /tmp/nova/.tox/genconfig
genconfig installdeps: -r/tmp/nova/test-requirements.txt
genconfig develop-inst: /tmp/nova
(snipped...)
genconfig runtests: PYTHONHASHSEED='582552523'
genconfig runtests: commands[0] | oslo-config-generator --config-file=etc/nova/nova-config-generator.conf
WARNING:oslo_config.generator:"idle_timeout" is missing a help string
----------------------------------------------------------------------------------------

In generated nova.conf.sample, there is not a help text for 'idle_timeout'.

----------------------------------------------------------------------------------------
(snipped...)
# The SQL mode to be used for MySQL sessions. This option, including the
# default, overrides any server-set SQL mode. To use whatever SQL mode is set by
# the server configuration, set this to no value. Example: mysql_sql_mode=
# (string value)
#mysql_sql_mode = TRADITIONAL

# (integer value)
#idle_timeout = 3600

# Maximum number of SQL connections to keep open in a pool. Setting a value of 0
# indicates no limit. (integer value)
#max_pool_size = <None>
(snipped...)
----------------------------------------------------------------------------------------

Environment:
OS Ubuntu 16.04.3 LTS
nova master(commit f01bda973a59a44f0443fb8ff9d23c3e8395873d)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/507006

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/507006
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=503a78b47c49e9361d606a967605796baaa1b87c
Submitter: Jenkins
Branch: master

commit 503a78b47c49e9361d606a967605796baaa1b87c
Author: Takashi NATSUME <email address hidden>
Date: Mon Sep 25 15:28:34 2017 +0900

    Deprecate idle_timeout in api_database

    In oslo.db, the 'idle_timeout' has been renamed to
    'connection_recycle_time' in
    I5e39d5ac81eaa8d85b1dfb18862fe27695ab8b96.

    So the 'idle_timeout' in 'api_database' group is
    renamed to 'connection_recycle_time' as well.

    Change-Id: Ie6e003be241d071904a99fdf6d83bc1186602f99
    Closes-Bug: #1716786

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 17.0.0.0b1 development milestone.