Measurements¶
Existing meters¶
For the list of existing meters see the tables under the Measurements page of Ceilometer in the Administrator Guide.
New measurements¶
Ceilometer is designed to collect measurements from OpenStack services and from other external components. If you would like to add new meters to the currently existing ones, you need to follow the guidelines given in this section.
Types¶
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) |
When you’re about to add a new meter choose one type from the above list, which is applicable.
Units¶
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’).
For a given meter, the units should NEVER, EVER be changed.
When the measurement does not represent a volume, the unit description should always describe WHAT is measured (ie: apples, disk, routers, floating IPs, etc.).
When creating a new meter, if another meter exists measuring something similar, the same units and precision should be used.
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 |
Naming convention¶
If you plan on adding meters, please follow the convention below:
Always use ‘.’ as separator and go from least to most discriminant word. For example, do not use ephemeral_disk_size but disk.ephemeral.size
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.
If you have any hesitation, come and ask in #openstack-telemetry
Meter definitions¶
Meters definitions by default, are stored in separate configuration
file, called ceilometer/data/meters.d/meters.yaml. This is essentially
a replacement for prior approach of writing notification handlers to consume
specific topics.
A detailed description of how to use meter definition is illustrated in the admin_guide.
