Monitor and roll back stack operations

Rollback triggers enable you to have AWS CloudFormation monitor the state of your application during stack creation and updating, and to roll back that operation if the application breaches the threshold of the alarms you've specified. For each rollback trigger you create, you specify the CloudWatch alarm that CloudFormation should monitor. CloudFormation monitors the specified alarms during the stack create or update operation, and for the specified amount of time after all resources have been deployed. If any of the alarms goes to ALARM state during the stack operation or the monitoring period, CloudFormation rolls back the entire stack operation.

You can set a monitoring time from the default of 0 up to 180 minutes. During this time, CloudFormation monitors all the rollback triggers after the stack creation or update operation deploys all necessary resources. If any of the alarms goes to ALARM state during the stack operation or this monitoring period, CloudFormation rolls back the entire stack operation. Then, for update operations, if the monitoring period expires without any alarms going to ALARM state, CloudFormation proceeds to dispose of old resources as usual. If you set a monitoring time but don't specify any rollback triggers, CloudFormation still waits the specified period of time before cleaning up old resources for update operations. You can use this monitoring period to perform any manual stack validation desired, and manually cancel the stack creation or update as necessary. If you set a monitoring time of 0 minutes, CloudFormation still monitors the rollback triggers during stack creation and update operations and rolls back the operation if an alarm goes to ALARM state. Then, for update operations with no breaching alarms, it begins disposing of old resources immediately once the operation completes.

By default, CloudFormation only rolls back stack operations if an alarm goes to ALARM state, not INSUFFICIENT_DATA state. To have CloudFormation roll back the stack operation if an alarm goes to INSUFFICIENT_DATA state as well, edit the CloudWatch alarm to treat missing data as breaching. For more information, see Configuring how CloudWatch alarms treat missing data in Amazon CloudWatch User Guide.

CloudFormation doesn't monitor rollback triggers when it rolls back a stack during an update operation.

You can add a maximum of 5 rollback triggers. To add a rollback trigger, specify the Amazon Resource Name (ARN) of the CloudWatch alarm. Currently, AWS::CloudWatch::Alarm and AWS::CloudWatch::CompositeAlarm types can be used as rollback triggers. For more information about CloudWatch alarms, see Using Amazon CloudWatch alarms in Amazon CloudWatch User Guide.

If a given CloudWatch alarm is missing, the entire stack operation fails and rolls back.

Be aware that access to Amazon CloudWatch requires credentials. Those credentials must have permissions to access AWS resources, such as retrieving CloudWatch metric data about your resources. For more information, see Authentication and access control for Amazon CloudWatch in Amazon CloudWatch User Guide.

To add rollback triggers during stack creation or updating

To add rollback triggers to a stack creation or update, specify the Amazon CloudWatch alarms in the Rollback configuration section.

1. During creating or updating a stack, on the Configure stack options page, under Advanced options, expand the Rollback configuration section.

2. Enter a monitoring time between 0 – 180 minutes. The default value is 0.

3. Specify the ARN of the CloudWatch alarm or composite alarm you want to use as a rollback trigger, and select Add CloudWatch alarm ARN.

   For example, the following is an ARN for a CloudWatch alarm or composite alarm, arn:aws:cloudwatch:us-east-1:123456789012:alarm:MyAlarmName.

4. Select Next and review the details of your stack.

5. After you review the stack creation settings and the estimated cost of your stack, choose Create stack to launch your stack.

Results: You've successfully added Amazon CloudWatch alarms to your stack.

To add rollback triggers to a change set

To add rollback triggers to a change set, create a change set by select your stack template and specify the Amazon CloudWatch alarms in the Rollback configuration section.

1. During creating or updating a change set, on the Configure stack options page, under Advanced options, expand the Rollback configuration section.

2. Enter a monitoring time between 0 – 180 minutes. The default value is 0.

3. Specify the ARN of the CloudWatch alarm or composite alarm you want to use as a rollback trigger, and select Add CloudWatch alarm ARN.

   For example, the following is an ARN for a CloudWatch alarm or composite alarm, arn:aws:cloudwatch:us-east-1:123456789012:alarm:MyAlarmName.

4. Select Next and review the details of your stack.

5. After you review the stack creation settings and the estimated cost of your stack, choose Create change set.

6. Review the Create change set module and select Create change set.

7. (Optional) To complete creating a new stack based on the change set, choose Execute, specify your rollback configuration, and then choose Execute change set.

Results: You've successfully added Amazon CloudWatch alarms to your change set.

To view rollback triggers for a stack

To view rollback triggers for a stack, see the Rollback configuration section.

1. On the Stacks page, select the stack you want to view from the list on the left.

2. On the Stack info tab, expand the Rollback configuration section.

Results: Rollback triggers are displayed in the Rollback configuration section, if rollback triggers were specified.

To view rollback triggers for a change set

To view rollback triggers for a change set, see the Rollback configuration section.

1. On the Stacks page, select the stack you want to view from the list on the left.

2. Select the Change sets tab, and select the change set you want to view.

3. Select the Input tab, and view the Rollback configuration section.

Results: Rollback triggers are displayed in the Rollback configuration section, if rollback triggers were specified.