[ocata][17.02] ceilometer errors due to incorrect swift API url usage with rados gateway: storage.containers.objects: Account GET failed

ceilometer-agent-central log is full of errors:

ceilometer-agent-central.log.1:2017-08-14 12:36:55.689 76729 ERROR ceilometer.agent.manager [-] Continue after error from storage.containers.objects: Account GET failed: http://10.232.40.209:80/swift/v1/AUTH_099a6960844445f48b7ed795c8ffeac2?format=json 404 Not Found [first 60 chars of response] {"Code":"NoSuchBucket","BucketName":"AUTH_099a6960844445f48b
ceilometer-agent-central.log.1:2017-08-14 12:36:55.689 76729 ERROR ceilometer.agent.manager raise ClientException.from_response(resp, 'Account GET failed', body)
ceilometer-agent-central.log.1:2017-08-14 12:36:55.689 76729 ERROR ceilometer.agent.manager ClientException: Account GET failed: http://10.232.40.209:80/swift/v1/AUTH_099a6960844445f48b7ed795c8ffeac2?format=json 404 Not Found [first 60 chars of response] {"Code":"NoSuchBucket","BucketName":"AUTH_099a6960844445f48b
ceilometer-agent-central.log.1:2017-08-14 12:36:56.949 76729 ERROR ceilometer.agent.manager [-] Continue after error from storage.containers.objects.size: Account GET failed: http://10.232.40.209:80/swift/v1/AUTH_099a6960844445f48b7ed795c8ffeac2?format=json 404 Not Found [first 60 chars of response] {"Code":"NoSuchBucket","BucketName":"AUTH_099a6960844445f48b
ceilometer-agent-central.log.1:2017-08-14 12:36:56.949 76729 ERROR ceilometer.agent.manager raise ClientException.from_response(resp, 'Account GET failed', body)
ceilometer-agent-central.log.1:2017-08-14 12:36:56.949 76729 ERROR ceilometer.agent.manager ClientException: Account GET failed: http://10.232.40.209:80/swift/v1/AUTH_099a6960844445f48b7ed795c8ffeac2?format=json 404 Not Found [first 60 chars of response] {"Code":"NoSuchBucket","BucketName":"AUTH_099a6960844445f48b

Errors indicate that ceilometer is polling the swift API for an object size. And it does not use code available specifically for radosgw:

https://github.com/openstack/ceilometer/blob/stable/ocata/ceilometer/objectstore/swift.py#L127 -L142 - this code is used (swift-specific)

https://github.com/openstack/ceilometer/blob/stable/ocata/ceilometer/objectstore/rgw.py#L121-L137
 instead of this (rados-gateway specific)

The messages would have reported radosgw.containers.objects.size not storage.containers.objects.size

Related info:

https://docs.openstack.org/ceilometer/latest/admin/telemetry-measurements.html#ceph-object-storage
https://review.openstack.org/#/c/151763/10/doc/source/measurements.rst

This is missing in our current implementation:

"In order to access Ceph from Telemetry, you need to specify a service group for radosgw in the ceilometer.conf configuration file along with access_key and secret_key of the admin user mentioned above."

Similar issue:
http://tracker.ceph.com/issues/19268