Shared backend config stanza

Registered by Patrick East

We don't have a nice way for backends to share common config parameters. Infact... we have a somewhat confusing model right now. As an example consider something like:

[DEFAULT]
enabled_backends = backend1, backend2
...
my_driver_param = foo
...

[backend1]
...
my_driver_param = bar

[backend2]
..
(not specifying the param)

Generally this is confused as thinking that backend1 will get 'bar' and backend2 will get 'foo' since its in the default section, unfortunately that 'foo' setting is completely ignored and backend2 gets whatever the default setting was for the driver.

The idea then is to be able to do something like:

[DEFAULT]
...

[common-or-shared-or-whatever-we-call-it]
my_driver_param = foo

[backend1]
...
my_driver_param = bar

[backend2]
..
(not specifying the param)

[backend3]
...
(also not specifying, maybe even a different volume driver... doesn't matter)

And the result being that backend2 and backend3 get 'foo', and backend1 gets its 'bar' value where it overwrote the shared one.

Blueprint information

Status:
Complete
Approver:
Sean McGinnis
Priority:
Medium
Drafter:
Patrick East
Direction:
Approved
Assignee:
Patrick East
Definition:
Approved
Series goal:
Accepted for pike
Implementation:
Implemented
Milestone target:
None
Started by
Eric Harney
Completed by
Eric Harney

Related branches

Sprints

Whiteboard

Gerrit topic: https://review.openstack.org/#q,topic:bp/shared-backend-config,n,z

Addressed by: https://review.openstack.org/330767
    Shared backend config stanza

Addressed by: https://review.openstack.org/335135
    Deprecate defining c-vol backends in DEFAULT

Addressed by: https://review.openstack.org/335299
    Add support for shared "backend_defaults" config

Addressed by: https://review.openstack.org/335672
    Don't merge - demo showing DEFAULT as a shared conf

(?)

Work Items

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