guestagent config for datastore_registry_ext needs to be cleaner

[Craig Vyvial]

If you want to override the guestagent managers its looks really nasty to have EVERY manager on a single line here.

datastore_registry_ext = mysql:my.guestagent.datastore.mysql.manager.Manager,percona:my.guestagent.datastore.mysql.manager.Manager

This needs to be tidied up and split out some way.
Ideally each of these should be on a single line.

datastore_registry_ext = mysql:my.guestagent.datastore.mysql.manager.Manager
datastore_registry_ext = percona:my.guestagent.datastore.mysql.manager.Manager

or maybe...

datastores = mysql,precona
[mysql]
manager = my.guestagent.datastore.mysql.manager.Manager
[percona]
manager = my.guestagent.datastore.percona.manager.Manager

After typing out the second idea i dont like it as much as something like the first way.

DEV LIST THREAD: http://lists.openstack.org/pipermail/openstack-dev/2014-July/039145.html

[Denis M. (dmakogon)]

Not quite sure about which solution can be more user-friendly. But iirc, oslo.config allows to define custom attribute type.

[Amrith Kumar (amrith)]

A change is in review now.

See: https://review.openstack.org/#/c/284434/

[OpenStack Infra (hudson-openstack)]

Change abandoned by amrith (<email address hidden>) on branch: master
Review: https://review.openstack.org/284434
Reason: time to abandon based on the midcycle conversation re: refactor