Define paste entrypoints

[Brant Knudson]

oslo.middleware middlewares should define the entry points for the factories.

In setup.cfg:

[entry_points]
paste.filter_factory =
    request_id = oslo_middleware:RequestId.factory

(Or whatever you want to call the entrypoint)

Then we can use it in keystone instead of defining our own.

Here's how it's used in keystone:

[filter:request_id]
use = egg:keystone#request_id

So we'd change to "use = egg:oslo.middleware#request_id".

And then eventually we can remove the line from keystone-paste.ini.

[Doug Hellmann (doug-hellmann)]

We need to be careful about staging the upgrade for this in keystone. The grenade tests should fail if keystone removes the entry point setting in its setup.cfg, but it should be possible to update the paste file and add an entry point to oslo.middleware in the same cycle, then remove the entry point from keystone in the next cycle.

However, it's not clear what paste will do when it finds multiple entry points with the same name. We should test that, maybe it will work fine, but if not we might need to use a different name for the same factory in oslo.middlware to avoid the conflict.

[Tom Cocozzello (tjcocozz-deactivatedaccount)]

Review: https://review.openstack.org/#/c/230156/

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/263155

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/263155
Committed: https://git.openstack.org/cgit/openstack/keystone/commit/?id=5fe12468cfd8445f7ebdd7d6ac940e2b4228a37c
Submitter: Jenkins
Branch: master

commit 5fe12468cfd8445f7ebdd7d6ac940e2b4228a37c
Author: zhang.lei <[e-mail]>
Date: Mon Jan 4 14:48:25 2016 +0800

    Define paste entrypoints

    Define filter factories so other projects can reference them by name
    and can take advantage of the python egg instead of referencing
    by the direct path.

    Change-Id: I8f2b409e35b44323ef1a4488de5964a0f1bd7cdc
    Closes-Bug: 1500509

[Thierry Carrez (ttx)]

This issue was fixed in the openstack/keystone 9.0.0.0b2 development milestone.