Bug 1416546

Description of problem: 
mongodb fills disk with event data of "objectstore.http.request" with gnocchi driver=swift


Version-Release number of selected component (if applicable):


How reproducible: 100%


Steps to Reproduce:
1. Create overcloud (non ceph) 
2. Deploy a few vms

Actual results: 
mongodb fills with many "objectstore.http.request" filling up system disk


Expected results:


Additional info: 
Below is a breakdown of document count by event type in collection after a few days of running in overcloud with 4 compute nodes and 10 VMs

DB size : ceilometer event colletion size  12GB

Event Document Count
----------------------------------
"objectstore.http.request", 3505417
"identity.authenticate", 34043
"compute.instance.exists", 446
"compute.instance.update", 70
"identity.endpoint.created", 39
"identity.role_assignment.created", 15
"identity.service.created", 13
"identity.user.created", 12
"scheduler.select_destinations.start", 10
"scheduler.select_destinations.end", 10
"port.update.start", 10
"port.update.end", 10
"port.create.start", 10
"port.create.end", 10
"compute.instance.create.start", 10
"compute.instance.create.end", 10
"identity.role.created", 5
"image.send", 4
"identity.user.updated", 3
"image.update", 2
"identity.project.created", 2
"identity.domain.created", 2
"subnet.create.start", 1
"subnet.create.end", 1
"network.create.start", 1
"network.create.end", 1
"image.upload", 1
"image.prepare", 1
"image.create", 1
"image.activate", 1
"identity.region.created", 1
"identity.project.updated", 1