AWS CloudFormation
User Guide (API Version 2010-05-15)

Viewing a Change Set

After you create a change set, you can view the proposed changes before executing them. You can use the AWS CloudFormation console, AWS CLI, or AWS CloudFormation API to view change sets. The AWS CloudFormation console provides a summary of the changes and a detailed list of changes in JSON format. The AWS CLI and AWS CloudFormation API return a detailed list of changes in JSON format.

To view a change (console)

  1. In the AWS CloudFormation console, choose the stack that has the change set that you want to view.

  2. In the stack detail pane, choose Change Sets to view a list of the stack's change sets.

  3. Choose the change set that you want to view.

    The AWS CloudFormation console directs you to the change set's detail page, where you can see the time the change set was created, its status, the input used to generate the change set, and a summary of changes.

    In the Changes section, each line represents a resource that AWS CloudFormation will add, delete, or modify. AWS CloudFormation adds a resource when you add a resource to the stack's template. AWS CloudFormation deletes a resource when you delete an existing resource from the stack's template. AWS CloudFormation modifies a resource when you change the properties of a resource. Note that a modification can cause the resource to be interrupted or replaced (recreated). For more information about resource update behaviors, see Update Behaviors of Stack Resources.

    To focus on specific changes, use the filter view. For example, filter for a specific resource type, such as AWS::EC2::Instance. To filter for a specific resource, specify its logical or physical ID, such as myWebServer or i-123abcd4.

    If you want to consider other changes before you decide which changes to make, create additional change sets.

To view a change set (AWS CLI)

  1. To get the ID of the change set, run the aws cloudformation list-change-sets command.

    Specify the stack ID of the stack that has the change set that you want to view, as shown in the following example:

    aws cloudformation list-change-sets --stack-name arn:aws:cloudformation:us-east-1:123456789012:stack/SampleStack/1a2345b6-0000-00a0-a123-00abc0abc000

    AWS CloudFormation returns a list of change sets, similar to the following:

    { "Summaries": [ { "StackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/SampleStack/1a2345b6-0000-00a0-a123-00abc0abc000", "Status": "CREATE_COMPLETE", "ChangeSetName": "SampleChangeSet", "CreationTime": "2016-03-16T20:44:05.889Z", "StackName": "SampleStack", "ChangeSetId": "arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet/1a2345b6-0000-00a0-a123-00abc0abc000" }, { "StackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/SampleStack/1a2345b6-0000-00a0-a123-00abc0abc000", "Status": "CREATE_COMPLETE", "ChangeSetName": "SampleChangeSet-conditional", "CreationTime": "2016-03-16T21:15:56.398Z", "StackName": "SampleStack", "ChangeSetId": "arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet-conditional/1a2345b6-0000-00a0-a123-00abc0abc000" }, { "StackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/SampleStack/1a2345b6-0000-00a0-a123-00abc0abc000", "Status": "CREATE_COMPLETE", "ChangeSetName": "SampleChangeSet-replacement", "CreationTime": "2016-03-16T21:03:37.706Z", "StackName": "SampleStack", "ChangeSetId": "arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet-replacement/1a2345b6-0000-00a0-a123-00abc0abc000" } ] }
  2. Run the aws cloudformation describe-change-set command, specifying the ID of the change set that you want to view. For example:

    aws cloudformation describe-change-set --change-set-name arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet/1a2345b6-0000-00a0-a123-00abc0abc000

    AWS CloudFormation returns information about the specified change set:

    { "StackId": "arn:aws:cloudformation:us-east-1:123456789012:stack/SampleStack/1a2345b6-0000-00a0-a123-00abc0abc000", "Status": "CREATE_COMPLETE", "ChangeSetName": "SampleChangeSet-direct", "Parameters": [ { "ParameterValue": "testing", "ParameterKey": "Purpose" }, { "ParameterValue": "ellioty-useast1", "ParameterKey": "KeyPairName" }, { "ParameterValue": "t2.micro", "ParameterKey": "InstanceType" } ], "Changes": [ { "ResourceChange": { "ResourceType": "AWS::EC2::Instance", "PhysicalResourceId": "i-1abc23d4", "Details": [ { "ChangeSource": "DirectModification", "Evaluation": "Static", "Target": { "Attribute": "Tags", "RequiresRecreation": "Never" } } ], "Action": "Modify", "Scope": [ "Tags" ], "LogicalResourceId": "MyEC2Instance", "Replacement": "False" }, "Type": "Resource" } ], "CreationTime": "2016-03-17T23:35:25.813Z", "Capabilities": [], "StackName": "SampleStack", "NotificationARNs": [], "ChangeSetId": "arn:aws:cloudformation:us-east-1:123456789012:changeSet/SampleChangeSet-direct/9edde307-960d-4e6e-ad66-b09ea2f20255" }

    The Changes key lists changes to resources. If you were to execute this change set, AWS CloudFormation would update the tags of the i-1abc23d4 EC2 instance. For a description of each field, see the Change data type in the AWS CloudFormation API Reference.

    For additional examples of change sets, see Example Change Sets.