Ceilometer upgrade is coupled to other projects

[Sean Dague]

Ceilometer's pattern of installing it's own code into the paste pipelines of other projects means that ceilometer must be attomically upgraded with all the other components in OpenStack that it does this with.

Ceilometer should not be putting code into the address space of other projects, as it makes the upgrade unit of work much larger, and creates additional coupling between all the projects.

[Chris Dent (cdent)]

See the comments on https://review.openstack.org/#/c/117745/ for a bit of history on this issue.

The notification generation code should not be in ceilometer, at all.

[gordon chung (chungg)]

@Sean, i might have missed your response to my question to your ML post but what was the original bug that you created a workaround for? http://lists.openstack.org/pipermail/openstack-dev/2014-December/052121.html

reason i asked is so we can vet the fix we do implement.

[gordon chung (chungg)]

swift middleware branched from ceilometer lib into it's own package... ceilometermiddleware functions in same way as keystonemiddleware so upgrading issues are resolved.

devstack update: https://review.openstack.org/#/c/155473/
openstack-manual update: https://review.openstack.org/#/c/158778/