Built-in Policies
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description and details on the Cloudify built-in policies
Host Failure
Type: cloudify.policies.types.host_failure
Properties
| Property | Required | Type | Description |
|---|---|---|---|
| service | yes | list | A list of regular expressions matching service names. |
Description
This policy is based on intercepting expired events.
The first monitoring event sent by a certain node instance will add this event type (determined by the event’s service and host properties) to the policy engine index (Riemann’s index mechanism). Later, if this type of event does not get sent for a period of 60 seconds for this particular node instance, it gets expired.
When an event expires and has been sent by a service that matches one of the service property regular expressions of the policy specified in the blueprint, the host failure policy passes this event to the restraints check and eventually processes the policy’s triggers. It adds the diagnose field with value “heart-beat-failure” to the event. Additionally, the event’s state gets changed to “triggering_state”.
This policy’s implementation can be found at github.
It is based on Riemann’s expired? function.
Threshold
Type: cloudify.policies.types.threshold
Properties:
| Property | Required | Type | Description |
|---|---|---|---|
| service | yes | string | A regular expression that matches the service name. |
| threshold | yes | float | The metric threshold value. |
| upper_bound | no | boolean | If true, process triggers for metrics with values higher than threshold; otherwise, the threshold is a lower bound (default: true). |
| stability_time | no | int | How long (in seconds) a threshold must be breached before the triggers will be processed (default: 0). |
Description:
When for stability_time seconds all non-expired events have metric values that breach the threshold, the policy passes the last event to the restraints check and eventually processes the policy’s triggers.
The event’s state gets changed to “triggering_state”.
This policy’s implementation can be found at github.
It is based on Riemann’s stable function.
Exponential Weighted Moving Average
Type: cloudify.policies.types.ewma_stabilized
Properties
| Property | Required | Type | Description |
|---|---|---|---|
| service | yes | string | A regular expression that matches the service name. |
| threshold | yes | float | The metric threshold value. |
| upper_bound | no | boolean | If true, process triggers for metrics with values higher than threshold; otherwise, the threshold is a lower bound (default: true). |
| ewma_timeless_r | no | float | The ratio between successive events. The smaller it is, the smaller impact on the computed value the most recent event has (default: 0.5). |
Description
This policy calculates the weighted average of events metrics over time.
When the average breaches the threshold, the policy passes the last event to the restraints check and eventually processes the policy’s triggers.
The event’s state gets changed to “triggering_state”.
This policy’s implementation can be found at github.
It is based on Riemann’s ewma-timeless function.