You can use the change set feature to update running stacks. You can preview how proposed changes to a stack may affect your running resources. ROS makes changes to stacks only after you execute change sets. You can use the ROS console, Alibaba Cloud CLI, or ROS API to create and manage change sets.
The limits on change sets are as follows:
- A stack can contain up to 20 change sets.
- Change sets only reflect stack changes. They do not indicate whether stacks have been updated.
- Change sets do not check whether the upper limit of your account has been reached, whether resources that cannot be updated will be updated, or whether your account has sufficient permissions to modify resources. Each of these limitations can cause stack updates to fail. If stack updates fail, ROS attempts to roll back your resources to their original status.
Stack update process
The process of using change sets to update a stack is as follows:
- Create a change set by submitting changes for the stack that you want to update. You can submit a modified template or modified input parameter values. ROS compares your stack with the submitted changes and generates a change set.
- View the stack settings and resources that will be changed in the change set. For example, you can view the resources that ROS will add, modify, or delete.
- Optional. If you need to make additional changes before you execute a change set, create additional change sets. Creating multiple change sets can help you understand and evaluate how different changes will affect your resources. You can also delete change sets that are no longer needed to avoid executing inapplicable change sets accidentally.
- Execute the change set that you need to apply to your stack.
Notice After you execute a change set, other change sets associated with the stack will become invalid and be deleted.
- The stack is being updated. After the update is complete, you can view the update result.
The following table describes the features of change sets.
|Create a change set||If you need to create a change set for a running stack, follow the instructions in this topic to modify the template or template parameters.|
|View a change set||After you create a change set, you can view the change records and JSON-formatted change details.|
|Execute a change set||After you create a change set for a stack, you must execute the change set to update the stack.|
|Delete a change set||If a change set is no longer needed, you can delete it to avoid unexpected or accidental stack changes.|