Measurements

Three type of meters are defined in ceilometer:

Type	Definition
Cumulative	Increasing over time (instance hours)
Gauge	Discrete items (floating IPs, image uploads) and fluctuating values (disk I/O)
Delta	Changing over time (bandwidth)

Units

1. Whenever a volume is to be measured, SI approved units and their approved symbols or abbreviations should be used. Information units should be expressed in bits (‘b’) or bytes (‘B’).
2. For a given meter, the units should NEVER, EVER be changed.
3. When the measurement does not represent a volume, the unit description should always described WHAT is measured (ie: apples, disk, routers, floating IPs, etc.).
4. When creating a new meter, if another meter exists measuring something similar, the same units and precision should be used.
5. Meters and samples should always document their units in Ceilometer (API and Documentation) and new sampling code should not be merged without the appropriate documentation.

Dimension	Unit	Abbreviations	Note
None	N/A		Dimension-less variable
Volume	byte	B
Time	seconds	s

Here are the meter types by components that are currently implemented:

Compute (Nova)

All meters are related to the guest machine, not the host.

Name	Type	Unit	Resource	Origin	Note
instance	Gauge	instance	inst ID	both	Duration of instance
instance:<type>	Gauge	instance	inst ID	both	Duration of instance <type> (openstack types)
memory	Gauge	MB	inst ID	notification	Volume of RAM in MB
cpu	Cumulative	ns	inst ID	pollster	CPU time used
cpu_util	Gauge	%	inst ID	pollster	Average CPU utilisation
vcpus	Gauge	vcpu	inst ID	notification	Number of VCPUs
disk.read.requests	Cumulative	request	inst ID	pollster	Number of read requests
disk.write.requests	Cumulative	request	inst ID	pollster	Number of write requests
disk.read.bytes	Cumulative	B	inst ID	pollster	Volume of read in B
disk.write.bytes	Cumulative	B	inst ID	pollster	Volume of write in B
disk.root.size	Gauge	GB	inst ID	notification	Size of root disk in GB
disk.ephemeral.size	Gauge	GB	inst ID	notification	Size of ephemeral disk in GB
network.incoming.bytes	Cumulative	B	iface ID	pollster	number of incoming bytes on the network for a VM interface
network.outgoing.bytes	Cumulative	B	iface ID	pollster	number of outgoing bytes on the network for a VM interface
network.incoming.packets	Cumulative	packets	iface ID	pollster	number of incoming packets for a VM interface
network.outgoing.packets	Cumulative	packets	iface ID	pollster	number of outgoing packets for a VM interface

At present, most of the Nova meters will only work with libvirt front-end hypervisors while test coverage was mostly done based on KVM. Contributors are welcome to implement other virtualization backends’ meters or complete the existing ones.

Network (Neutron)

Name	Type	Unit	Resource	Origin	Note
network	Gauge	network	netw ID	notification	Duration of network
network.create	Delta	network	netw ID	notification	Creation requests for this network
network.update	Delta	network	netw ID	notification	Update requests for this network
subnet	Gauge	subnet	subnt ID	notification	Duration of subnet
subnet.create	Delta	subnet	subnt ID	notification	Creation requests for this subnet
subnet.update	Delta	subnet	subnt ID	notification	Update requests for this subnet
port	Gauge	port	port ID	notification	Duration of port
port.create	Delta	port	port ID	notification	Creation requests for this port
port.update	Delta	port	port ID	notification	Update requests for this port
router	Gauge	router	rtr ID	notification	Duration of router
router.create	Delta	router	rtr ID	notification	Creation requests for this router
router.update	Delta	router	rtr ID	notification	Update requests for this router
ip.floating	Gauge	ip	ip ID	both	Duration of floating ip
ip.floating.create	Delta	ip	ip ID	notification	Creation requests for this floating ip
ip.floating.update	Delta	ip	ip ID	notification	Update requests for this floating ip

Image (Glance)

Name	Type	Unit	Resource	Origin	Note
image	Gauge	image	image ID	both	Image polling -> it (still) exists
image.size	Gauge	B	image ID	both	Uploaded image size
image.update	Delta	image	image ID	notification	Number of update on the image
image.upload	Delta	image	image ID	notification	Number of upload of the image
image.delete	Delta	image	image ID	notification	Number of delete on the image
image.download	Delta	B	image ID	notification	Image is downloaded
image.serve	Delta	B	image ID	notification	Image is served out

Volume (Cinder)

Name	Type	Unit	Resource	Origin	Note
volume	Gauge	volume	vol ID	notification	Duration of volune
volume.size	Gauge	GB	vol ID	notification	Size of volume

Make sure Cinder is properly configured first: see Installing Manually.

Object Storage (Swift)

Name	Type	Volume	Resource	Origin	Note
storage.objects	Gauge	objects	store ID	pollster	Number of objects
storage.objects.size	Gauge	B	store ID	pollster	Total size of stored objects
storage.objects.containers	Gauge	containers	store ID	pollster	Number of containers
storage.objects.incoming.bytes	Delta	B	store ID	notification	Number of incoming bytes
storage.objects.outgoing.bytes	Delta	B	store ID	notification	Number of outgoing bytes
storage.api.request	Delta	request	store ID	notification	Number of API requests against swift

In order to use storage.objects.incoming.bytes and storage.outgoing.bytes, one must configure Swift as described in Installing Manually. Note that they may not be updated right after an upload/download, since Swift takes some time to update the container properties.

Energy (Kwapi)

Name	Type	Volume	Resource	Origin	Note
energy	Cumulative	kWh	probe ID	pollster	Amount of energy
power	Gauge	W	probe ID	pollster	Power consumption

Dynamically retrieving the Meters via ceilometer client

To retrieve the available meters that can be queried given the actual resource instances available, use the meter-list command:

$ ceilometer meter-list -s openstack
+------------+-------+--------------------------------------+---------+----------------------------------+
| Name       | Type  | Resource ID                          | User ID | Project ID                       |
+------------+-------+--------------------------------------+---------+----------------------------------+
| image      | gauge | 09e84d97-8712-4dd2-bcce-45970b2430f7 |         | 57cf6d93688e4d39bf2fe3d3c03eb326 |

Naming convention

If you plan on adding meters, please follow the convention bellow:

1. Always use ‘.’ as separator and go from least to most discriminent word. For example, do not use ephemeral_disk_size but disk.ephemeral.size
2. When a part of the name is a variable, it should always be at the end and start with a ‘:’. For example do not use <type>.image but image:<type>, where type is your variable name.
3. If you have any hesitation, come and ask in #openstack-metering

User-defined sample metadata (nova only)

Users are allowed to add additional metadata to samples of nova meter. These additional metadata are stored in ‘resource_metadata.user_metadata.*’ of the sample To do so, users should add nova user metadata prefixed with ‘metering.’:

::

$ nova boot –meta metering.custom_metadata=a_value my_vm

Note: The name of the metadata shouldn’t exceed 256 characters otherwise it will be cut off. Also, if it has ‘.’, this will be replaced by a ‘_’ in ceilometer.