# Alarms
  
  ## Info
  
  Alarms bind alerting rules, entities, and notification plans into a logical unit. Alarms are responsible for determining a state (```OK```, ```WARNING``` or ```CRITICAL```) based on the result of a Check, and executing a notification plan whenever that state changes. You create alerting rules by using the alarm DSL. For information about using the alarm language, refer to the [reference documentation](http://docs.rackspace.com/cm/api/v1.0/cm-devguide/content/alerts-language.html).
  
  ## Setup
  
  Alarms are sub-resources of Entities:
  
  ```php
  $alarmId = 'alAAAA';
  $alarm = $check->getAlarm();
  ```
  
  For more information about working with Checks, please see the [appropriate documentation](Checks.md).
  
  ## Attributes
  
  Name|Description|Required?|Method
  ---|---|---|---
  check_id|The ID of the check to alert on.|Required|`getCheckId()`
  notification_plan_id|The ID of the notification plan to execute when the state changes.|Optional|`getNotificationPlanId()`
  criteria|The alarm DSL for describing alerting conditions and their output states.|Optional|`getCriteria()`
  disabled|Disable processing and alerts on this alarm|Optional|`isDisabled()` <`bool`>
  label|A friendly label for an alarm.|Optional|`getLabel()`
  metadata|Arbitrary key/value pairs.|Optional|`getMetadata()`
  
  ## Create Alarm
  ```php
  $alarm->create(array(
  	'check_id' => 'chAAAA',
  	'criteria' => 'if (metric["duration"] >= 2) { return new AlarmStatus(OK); } return new AlarmStatus(CRITICAL);',
  	'notification_plan_id' => 'npAAAAA'
  ));
  ```
  
  ## List Alarms
  ```php
  $alarms = $entity->getAlarms();
  
  foreach ($alarms as $alarm) {
  	echo $alarm->getId();
  }
  ```
  
  ## Update and delete Alarm
  ```php
  // Update
  $alarm->update(array(
  	'criteria' => 'if (metric["duration"] >= 5) { return new AlarmStatus(OK); } return new AlarmStatus(CRITICAL);'
  ));
  
  // Delete
  $alarm->delete();
  ```