Auto Scaling provides the event notification feature to help you monitor the scaling events that happen in your scaling group. After you create advanced notification rules or regular notification rules for your scaling group, Auto Scaling sends event notifications to CloudMonitor or Message Service (MNS). This allows you to obtain dynamic information about your scaling group at the earliest opportunity, and your scaling group can be automatically managed.

Notification rules

Auto Scaling supports the following notification rules:

  • Advanced notification rule: This type of notification rule enables the automatic management of scaling events.
  • Regular notification rule: If you use this type of notification rule, you must manually manage scaling events.

The following table describes the two types of notification rules.

Notification rule Description
Advanced notification rule Auto Scaling sends event notifications to CloudMonitor, MNS topics, or MNS queues after scaling activities are triggered in the scaling group. For more information, see Create an advanced notification rule.
  • In CloudMonitor, you can query and view statistics on system events of various cloud services, including Auto Scaling. This way, you can obtain the status of your scaling group at the earliest opportunity. For information about the event monitoring feature of CloudMonitor, see View cloud service events.
  • MNS provides the MNS topic and MNS queue service models. MNS is a distributed message service that allows you to transfer data and messages among distributed components, and build loosely coupled systems. For information about the MNS topics and queues, see What is MNS?.
    • The MNS queue is a point-to-point messaging model that supports concurrent communications with high reliability. You can use the MNS queue model if you want to send a message to only one message consumer.
    • The MNS topic is a publish/subscribe messaging model. The publisher produces a message to a topic, and then all subscribers to the topic receive and consume the message. In the MNS topic model, messages can be pushed to subscribers by using various methods and to multiple servers. Subscribers can receive messages from various channels.
Regular notification rule Auto Scaling sends event notifications by text message, internal message, and email after a scaling activity succeeds, fails, or is rejected in your scaling group. After you receive the event notifications, you must manually resolve the issues if exceptions occur. For more information, see Create a regular notification rule.
Note After you create advanced notification rules for your scaling group, you cannot create regular notification rules. You must delete all advanced notification rules before you can create regular notification rules for your scaling group.

Event notification examples

The following section provides examples of event notifications. For information about how to create an advanced notification rule, see Create an advanced notification rule.

  • Event notifications by using CloudMonitor

    In this example, the Notification Method parameter is set to CloudMonitor, and the Event parameter is set to Successful Scale-out and Scale-out Started. After the scale-out activity is triggered, CloudMonitor receives a notification and displays the events. In the following figure, the events that a scale-out activity starts and the scale-out activity succeeds are displayed.

    Event notification overview - Event notifications by using CloudMonitor
    Note In the CloudMonitor console, you can obtain dynamic information about your scaling group. You can also create alert rules. This way, CloudMonitor sends alert notifications to contacts by text message or email at the same time when alerts are reported. This improves O&M efficiency.
  • Event notifications by using MNS topics

    In this example, the Notification Method parameter is set to MNS Topic, the MNS topic that is created in the region in which the scaling group resides is selected, and the Event parameter is set to Successful Scale-in and Scale-in Started. After the scale-in activity is triggered, Auto Scaling sends an event notification to the MNS topic. Then, the MNS topic pushes the notification to the subscribers of the topic. In the following figure, a scale-in activity is triggered. In the figure, the number of notifications that correspond to the MNS topic increases. You can click View Subscriptions to view the notification details.

    The MNS topic does not support the direct consumption of notifications. You must subscribe to the MNS topic by using an MNS queue, an HTTP request, or an email. When the MNS topic receives a notification, the MNS topic pushes the notification to the subscribers. This way, multiple subscribers separately consume the notification from the same publisher. This improves the efficiency of automatic management.

    Event notification overview - Event notifications by using MNS topics
  • Event notifications by using MNS queues

    In this example, the Notification Method parameter is set to MNS Queue, the MNS queue that is created in the region in which the scaling group resides is selected, and the Event parameter is set to Scale-out Failed and Scale-out Started. If the scale-out activity fails, Auto Scaling sends an event notification to the MNS queue and allows contacts to manage and consume the notification. In the following figure, a scale-out activity fails. In the figure, the number of available notifications that correspond to the MNS queue increases.

    You can manage notifications in a flexible manner. You can consume, delay, activate, or delete notifications based on your business requirements.

    Event notification overview - Event notifications by using MNS queues

References

The following table describes the references of the event notification feature.

Documentation Operation API reference
Create an advanced notification rule Create an advanced notification rule CreateNotificationConfiguration
Modify an advanced notification rule ModifyNotificationConfiguration
Delete an advanced notification rule DeleteNotificationConfiguration
View an advanced notification rule
Create a regular notification rule Create a regular notification rule N/A