max_pool_size is not dynamically allocated by the number of workers

Nobuto, the nova-cloud-controller charm has a config option "neutron-alchemy-flags" that can be used to set arbitrary sqlalchemy config values. Having this value set dynamically might be nice but for now you should at least be able to set this parameter manually.

Hi Edward,

> Nobuto, the nova-cloud-controller charm has a config option "neutron-
> alchemy-flags" that can be used to set arbitrary sqlalchemy config
> values. Having this value set dynamically might be nice but for now you
> should at least be able to set this parameter manually.

I know "neutron-alchemy-flags". But this time I mean alchemy settings for
*nova*. There is no way for it at this moment as far as I know.

Ah yes indeed, sorry. So we should add a 'nova-alchemy-flags' to allow sqlalchemy config options to be set for Nova as well. I'll get that queued up.

@Edward,

I still prefer dynamic max_pool_size instead of *-alchemy-flags. Now that neutron-api charm is there, neutron-alchemy-flags is no longer used since no neutron service is running on nova-cloud-controller node. Besides, assuming the situation to adjust worker-multiplier, we need to tweak two configs(worker-multiplier and nova-alchemy-flags) at the same time if we adopt nova-alchemy-flags approach. Instead, max_pool_size={{ workers * X }} in nova [database] template makes our life easy like neutron-api charm, IMHO.

Nobuto, a *-alchemy-flags option is provided to allow any of the options in https://github.com/openstack/oslo.db/blob/master/oslo_db/options.py (when available in respective project) to be modified/set. Therefore I think it still make sense to add a nova-alchemy-flags option. What we could also do is if no nova-alchemy-flags are provided we could have max_pool_size set to num_cpu_cores * worker-multiplier by default. Would that work for you? That way you get your optimised default and you also get the option to override it.

Yes, easy dynamic max_pool_size + expert mode with *-alchemy-flags sounds good to me.
When I requested a way to customize alchemy flags for neutron (maybe a year ago?), I thought some flags in addition to max_pool_size were needed. In the end, I realized just setting max_pool_size sufficed most of the cases.

Ok thanks, I'll get that done.