Designate should use "sqlalchemy" pool manager cache driver instead of "memcached"

Fix proposed to branch: master
Review: https://review.openstack.org/#/c/529079/

Hi Tytus

Any reason why memcache is not a good idea? I'm not convinced as to the need to expose this as a configuration option - charms are permitted to be opinionated where that's desirable.

James,

I'll capture all information around that and will get back to you with a detailed use case soon.

Hi James,

Based on the discussion with Graham Hayes (core Designate developer & original author) the "sqlalchemy" driver is needed for the deployments which require the cache to be resilient, especially deployments with huge zone sizes (hundreds of MB).

Although my environment is not so huge, I would still ask for enabling this option. The change is pretty simple, the "pool_manager_cache:sqlalchemy" section in "designate.conf" file is already configured by the existing templates, and the "memcache" would still remain the default option.

I've just talked to James offline and we agreed to switch to "sqlalchemy" without introducing charm option. I'll re-write the patch next week.

Reviewed: https://review.openstack.org/529079
Committed: https://git.openstack.org/cgit/openstack/charm-designate/commit/?id=ad34f1e889d9bf91ae6ee92f597534857e6e98b7
Submitter: Zuul
Branch: master

commit ad34f1e889d9bf91ae6ee92f597534857e6e98b7
Author: Tytus Kurek <email address hidden>
Date: Mon Jan 29 09:30:58 2018 +0100

    Change pool manager cache driver

    This patchset changes the default pool manager cache driver used by
    the designate charm from "memcached" to "sqlalchemy".

    Change-Id: If61a28f572137b0e3041d17bd9296929074faf7d
    Closes-Bug: #1739012