15. Measure cloud resources

Telemetry measures cloud resources in OpenStack. It collects data related to billing. Currently, this metering service is available through only the ceilometer command-line client.

To model data, Telemetry uses the following abstractions:

Meter

Measures a specific aspect of resource usage, such as the existence of a running instance, or ongoing performance, such as the CPU utilization for an instance. Meters exist for each type of resource. For example, a separate cpu_util meter exists for each instance. The life cycle of a meter is decoupled from the existence of its related resource. The meter persists after the resource goes away.

A meter has the following attributes:

String name
A unit of measurement
A type, which indicates whether values increase monotonically (cumulative), are interpreted as a change from the previous value (delta), or are stand-alone and relate only to the current duration (gauge)

Sample

An individual data point that is associated with a specific meter. A sample has the same attributes as the associated meter, with the addition of time stamp and value attributes. The value attribute is also known as the sample volume.

Statistic

A set of data point aggregates over a time duration. (In contrast, a sample represents a single data point.) The Telemetry service employs the following aggregation functions:

count. The number of samples in each period.
max. The maximum number of sample volumes in each period.
min. The minimum number of sample volumes in each period.
avg. The average of sample volumes over each period.
sum. The sum of sample volumes over each period.

Alarm

A set of rules that define a monitor and a current state, with edge-triggered actions associated with target states. Alarms provide user-oriented Monitoring-as-a-Service and a general purpose utility for OpenStack. Orchestration auto scaling is a typical use case. Alarms follow a tristate model of ok, alarm, and insufficient data. For conventional threshold-oriented alarms, a static threshold value and comparison operator govern state transitions. The comparison operator compares a meter statistic against a predefined evaluation window over a selected period of time. This evaluation window is a configurable value.

This example uses the heat client to create an auto-scaling stack and the ceilometer client to measure resources.

Create an auto-scaling stack by running the following command. The -f option specifies the name of the stack template file, and the -P option specifies the KeyName parameter as heat_key.
```
$ heat stack-create -f cfn/F17/AutoScalingCeilometer.yaml -P "KeyName=heat_key"
```

List the heat resources that were created:

$ heat resource-list
+--------------------------+-----------------------------------------+-----------------+----------------------+
| resource_name            | resource_type                           |resource_status | updated_time         |
+--------------------------+-----------------------------------------+-----------------+----------------------+
| CfnUser                  | AWS::IAM::User                          |CREATE_COMPLETE | 2013-10-02T05:53:41Z |
| WebServerKeys            | AWS::IAM::AccessKey                     |CREATE_COMPLETE | 2013-10-02T05:53:42Z |
| LaunchConfig             | AWS::AutoScaling::LaunchConfiguration   |CREATE_COMPLETE | 2013-10-02T05:53:43Z |
| ElasticLoadBalancer      | AWS::ElasticLoadBalancing::LoadBalancer |UPDATE_COMPLETE | 2013-10-02T05:55:58Z |
| WebServerGroup           | AWS::AutoScaling::AutoScalingGroup      |CREATE_COMPLETE | 2013-10-02T05:55:58Z |
| WebServerScaleDownPolicy | AWS::AutoScaling::ScalingPolicy         |CREATE_COMPLETE | 2013-10-02T05:56:00Z |
| WebServerScaleUpPolicy   | AWS::AutoScaling::ScalingPolicy         |CREATE_COMPLETE | 2013-10-02T05:56:00Z |
| CPUAlarmHigh             | OS::Ceilometer::Alarm                   |CREATE_COMPLETE | 2013-10-02T05:56:02Z |
| CPUAlarmLow              | OS::Ceilometer::Alarm                   |CREATE_COMPLETE | 2013-10-02T05:56:02Z |
+--------------------------+-----------------------------------------+-----------------+----------------------+

List the alarms that are set:

$ ceilometer alarm-list
+--------------------------------------+------------------------------+-------------------+---------+------------+-------------------------------+
| Alarm ID                             | Name                         | State             | Enabled | Continuous | Alarm condition               |
+--------------------------------------+------------------------------+-------------------+---------+------------+-------------------------------+
| 4f896b40-0859-460b-9c6a-b0d329814496 | as-CPUAlarmLow-i6qqgkf2fubs  | insufficient data | True    | False      | cpu_util < 15.0 during 1x 60s |
| 75d8ecf7-afc5-4bdc-95ff-19ed9ba22920 | as-CPUAlarmHigh-sf4muyfruy5m | insufficient data | True    | False      | cpu_util > 50.0 during 1x 60s |
+--------------------------------------+------------------------------+-------------------+---------+------------+-----------------------------+

List the meters that are set:

$ ceilometer meter-list
+--------------------------+------------+----------+-----------------------------------------------------------------------+------------------------------------+
| Name                     | Type       | Unit     | Resource ID                          | User ID                          | Project ID                       |
+--------------------------+------------+----------+-----------------------------------------------------------------------+------------------------------------+
| cpu                      | cumulative | ns       | 3965b41b-81b0-4386-bea5-6ec37c8841c1 | d1a2996d3b1f4e0e8645ba9650308011 | bf03bf32e3884d489004ac995ff7a61c |
| cpu                      | cumulative | ns       | 62520a83-73c7-4084-be54-275fe770ef2c | d1a2996d3b1f4e0e8645ba9650308011 | bf03bf32e3884d489004ac995ff7a61c |
| cpu_util                 | gauge      | %        | 3965b41b-81b0-4386-bea5-6ec37c8841c1 | d1a2996d3b1f4e0e8645ba9650308011 | bf03bf32e3884d489004ac995ff7a61c |
+--------------------------+------------+----------+-----------------------------------------------------------------------+------------------------------------+

List samples:

$ ceilometer sample-list -m cpu_util
+--------------------------------------+----------+-------+---------------+------+---------------------+
| Resource ID                          | Name     | Type  | Volume        | Unit | Timestamp           |
+--------------------------------------+----------+-------+---------------+------+---------------------+
| 3965b41b-81b0-4386-bea5-6ec37c8841c1 | cpu_util | gauge | 3.98333333333 | %    | 2013-10-02T10:50:12 |
+--------------------------------------+----------+-------+---------------+------+---------------------+

View statistics:

$ ceilometer statistics -m cpu_util
+--------+---------------------+---------------------+-------+---------------+---------------+---------------+---------------+----------+---------------------+---------------------+
| Period | Period Start        | Period End          | Count | Min           | Max           | Sum           | Avg           | Duration | Duration Start      | Duration End        |
+--------+---------------------+---------------------+-------+---------------+---------------+---------------+---------------+----------+---------------------+---------------------+
| 0      | 2013-10-02T10:50:12 | 2013-10-02T10:50:12 | 1     | 3.98333333333 | 3.98333333333 | 3.98333333333 | 3.98333333333 | 0.0      | 2013-10-02T10:50:12 | 2013-10-02T10:50:12 |
+--------+---------------------+---------------------+-------+---------------+---------------+---------------+---------------+----------+---------------------+---------------------+