:Manage a change set

Scenario

If you want to preview the impacts of a stack update on running resources before you update a stack, you can use the change set feature. Resource Orchestration Service (ROS) applies changes to the stack only after you execute the change set.

Limits

Change sets are subject to the following limits:

• You can create change sets only for stacks in specific states. For more information about the supported states, see Limits.

• You can associate up to 20 change sets with a stack.

• Change sets reflect only the changes of stacks. Change sets do not reflect whether stacks are successfully updated.

• You cannot use a change set to check whether you exceed an account limit, whether you update resources that cannot be updated, and whether you have insufficient permissions to modify resources. The items that cannot be checked by using a change set cause a stack update to fail. If a stack update fails, ROS attempts to roll back your resources to their original status.

Manage a change set to update a stack

This section describes how to manage a change set to update a stack.

1. Create a change set.

   You can create a change set to submit changes for the stack that you want to update. When you create a change set for a stack, you can submit a modified stack template or modified parameter values. ROS automatically compares the original stack data with the modified data that you submit to generate the change set. For more information, see Create a change set.

2. (Optional) View the change set.

   When you view the change set of a stack that you want to update, you can check the JSON code that will be changed and the change records that will be generated. For example, you can view the resources that ROS will add, modify, or delete. For more information, see View a change set.

   Note

   If you want to add new changes when you view a change set, you can create a new change set for the stack. A stack that has multiple change sets can help you better understand and evaluate different changes that will affect your resources.

3. (Optional) Delete the change set.

   If the change set that you create does not meet your expectations, you can delete the change set to prevent it from being improperly executed. For more information, see Delete a change set.

4. Execute the change set.

   You can execute a change set that meets your expectations to apply the changes to your stack. For more information, see Execute a change set.

   Important

   After you execute a change set, ROS automatically deletes all change sets that are associated with the stack because they are no longer applicable to the updated stack.

5. View the update result of the stack.

   After you execute the change set, ROS starts to update the stack. After the update is complete, you can view the update result of the stack.