Gnocchi processes data from Ceilometer and stores the processed data which can be accessed by users. It correlates measurements from Ceilometer to resources and metrics.
Metric: A resource property which can be measured. For example the CPU, memory usage etc.
Resource: These can be instances, volumes, networks etc.
gnocchiclient
The gnocchi command line tool can be installed using pip:
pip install gnocchiclient
This provides the following Openstack commands:
openstack [metric-command] metric aggregates metric archive-policy create metric archive-policy delete metric archive-policy list metric archive-policy show metric archive-policy update metric archive-policy-rule create metric archive-policy-rule delete metric archive-policy-rule list metric archive-policy-rule show metric benchmark measures add metric benchmark measures show metric benchmark metric create metric benchmark metric show metric capabilities list metric create metric delete metric list metric measures add metric measures aggregation metric measures batch-metrics metric measures batch-resources-metrics metric measures show metric resource batch delete metric resource create metric resource delete metric resource history metric resource list metric resource search metric resource show metric resource update metric resource-type create metric resource-type delete metric resource-type list metric resource-type show metric resource-type update metric server version metric show metric status
Metrics
Metrics consist of:
Name: unique name for the metric
Unit (e.g. MB, ns, B/s)
Resource ID - where the measurement is from
Unique User ID (UUID): Identifies the metric
Archive policy: stores and aggregates the measures
Archive policies determine how long aggregates are kept and how they are aggregated. The archive policies can be seen using the command:
openstack metric archive-policy list +----------------------+-------------+-----------------------------------------+---------------------+ | name | back_window | definition | aggregation_methods | +----------------------+-------------+-----------------------------------------+---------------------+ | ceilometer-high | 0 | - points: 3600, timespan: 1:00:00, | mean | | | | granularity: 0:00:01 | | | | | - points: 1440, timespan: 1 day, | | | | | 0:00:00, granularity: 0:01:00 | | | | | - points: 8760, timespan: 365 days, | | | | | 0:00:00, granularity: 1:00:00 | | | ceilometer-high-rate | 0 | - points: 3600, timespan: 1:00:00, | rate:mean, mean | | | | granularity: 0:00:01 | | | | | - points: 1440, timespan: 1 day, | | | | | 0:00:00, granularity: 0:01:00 | | | | | - points: 8760, timespan: 365 days, | | | | | 0:00:00, granularity: 1:00:00 | | | ceilometer-low | 0 | - points: 8640, timespan: 30 days, | mean | | | | 0:00:00, granularity: 0:05:00 | | | ceilometer-low-rate | 0 | - points: 8640, timespan: 30 days, | rate:mean, mean | | | | 0:00:00, granularity: 0:05:00 | | +----------------------+-------------+-----------------------------------------+---------------------+
This table shows each archive-policy and how the raw datapoints for each metric is stored. As an example, let’s view the detail for one of the archive policies.
To view an archive policy, use the command:
openstack metric archive-policy show <archive-policy>
For example:
openstack archive-policy show ceilometer-high +---------------------+-------------------------------------------------------------------+ | Field | Value | +---------------------+-------------------------------------------------------------------+ | aggregation_methods | mean | | back_window | 0 | | definition | - points: 3600, timespan: 1:00:00, granularity: 0:00:01 | | | - points: 1440, timespan: 1 day, 0:00:00, granularity: 0:01:00 | | | - points: 8760, timespan: 365 days, 0:00:00, granularity: 1:00:00 | | name | ceilometer-high | +---------------------+-------------------------------------------------------------------+
For the archive policy ceilometer-high:
The mean is stored for each interval.
Stores one hour of data in one second intervals. (3600 data points)
Stores one day of data in one minute intervals. (1440 data points)
Stores one year of data in one hour intervals. (8760 data points)
To view the list of metrics:
openstack metric list
This will show the metrics which have been created/visible to the user.
To view the metric resources:
openstack metric resource list
To view the properties of a specific metric:
openstack metric show <metric-id>
Metrics can be created by the user using the gnocchiclient plugin in the Openstack CLI:
openstack metric create [-h] [--resource-id RESOURCE_ID] [-f {json,shell,table,value,yaml}]
[-c COLUMN] [--noindent] [--prefix PREFIX] [--max-width <integer>]
[--fit-width] [--print-empty]
[--archive-policy-name ARCHIVE_POLICY_NAME] [--unit UNIT]
[METRIC_NAME]
Note: Once a metric has been created, the archive policy attribute for that metric is fixed and cannot be changed.
References:
Gnocchi Documentation: https://gnocchi.xyz/stable_4.2/rest.html
Telemetry Measurements for Train: https://docs.openstack.org/ceilometer/train/admin/telemetry-measurements.html
Gnocchi Aggregation: https://medium.com/@berndbausch/how-i-learned-to-stop-worrying-and-love-gnocchi-aggregation-c98dfa2e20fe
Gnocchi Glossary: https://gnocchi.xyz/stable_4.2/glossary.html