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

Update

Custom resource provider requests with RequestType set to "Update" are sent when there's any change to the properties of the custom resource within the template. Therefore, custom resource code doesn't have to detect changes because it knows that its properties have changed when Update is being called.

Request

Update requests contain the following fields:

RequestType

Will be "Update".

RequestId

A unique ID for the request.

ResponseURL

The response URL identifies a presigned S3 bucket that receives responses from the custom resource provider to AWS CloudFormation.

ResourceType

The template developer-chosen resource type of the custom resource in the AWS CloudFormation template. Custom resource type names can be up to 60 characters long and can include alphanumeric and the following characters: _@-. You can't change the type during an update.

LogicalResourceId

The template developer-chosen name (logical ID) of the custom resource in the AWS CloudFormation template.

StackId

The Amazon Resource Name (ARN) that identifies the stack that contains the custom resource.

PhysicalResourceId

A required custom resource provider-defined physical ID that is unique for that provider.

ResourceProperties

The new resource property values that are declared by the template developer in the updated AWS CloudFormation template.

OldResourceProperties

The resource property values that were previously declared by the template developer in the AWS CloudFormation template.

Example

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{ "RequestType" : "Update", "RequestId" : "unique id for this update request", "ResponseURL" : "pre-signed-url-for-update-response", "ResourceType" : "Custom::MyCustomResourceType", "LogicalResourceId" : "name of resource in template", "StackId" : "arn:aws:cloudformation:us-east-2:namespace:stack/stack-name/guid", "PhysicalResourceId" : "custom resource provider-defined physical id", "ResourceProperties" : { "key1" : "new-string", "key2" : [ "new-list" ], "key3" : { "key4" : "new-map" } }, "OldResourceProperties" : { "key1" : "string", "key2" : [ "list" ], "key3" : { "key4" : "map" } } }

Responses

Success

If the custom resource provider is able to successfully update the resource, AWS CloudFormation expects the status to be set to "SUCCESS" in the response.

Status

Must be "SUCCESS".

RequestId

A unique ID for the request. This response value should be copied verbatim from the request.

LogicalResourceId

The template developer-chosen name (logical ID) of the custom resource in the AWS CloudFormation template. This response value should be copied verbatim from the request.

StackId

The Amazon Resource Name (ARN) that identifies the stack that contains the custom resource. This response value should be copied verbatim from the request.

PhysicalResourceId

This value should be an identifier unique to the custom resource vendor, and can be up to 1 Kb in size. The value must be a non-empty string and must be identical for all responses for the same resource.

NoEcho

Optional. Indicates whether to mask the output of the custom resource when retrieved by using the Fn::GetAtt function. If set to true, all returned values are masked with asterisks (*****). The default value is false.

Data

Optional. The custom resource provider-defined name-value pairs to send with the response. You can access the values provided here by name in the template with Fn::GetAtt.

Important

If the name-value pairs contain sensitive information, you should use the NoEcho field to mask the output of the custom resource. Otherwise, the values are visible through APIs that surface property values (such as DescribeStackEvents).

Example

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{ "Status" : "SUCCESS", "RequestId" : "unique id for this update request (copied from request)", "LogicalResourceId" : "name of resource in template (copied from request)", "StackId" : "arn:aws:cloudformation:us-east-2:namespace:stack/stack-name/guid (copied from request)", "PhysicalResourceId" : "custom resource provider-defined physical id", "Data" : { "keyThatCanBeUsedInGetAtt1" : "data for key 1", "keyThatCanBeUsedInGetAtt2" : "data for key 2" } }

Failed

If the resource can't be updated with a new set of properties, AWS CloudFormation expects the status to be set to "FAILED", along with a failure reason in the response.

Status

Must be "FAILED".

Reason

Describes the reason for a failure response.

RequestId

A unique ID for the request. This response value should be copied verbatim from the request.

LogicalResourceId

The template developer-chosen name (logical ID) of the custom resource in the AWS CloudFormation template. This response value should be copied verbatim from the request.

StackId

The Amazon Resource Name (ARN) that identifies the stack that contains the custom resource. This response value should be copied verbatim from the request.

PhysicalResourceId

This value should be an identifier unique to the custom resource vendor, and can be up to 1 Kb in size. The value must be a non-empty string and must be identical for all responses for the same resource.

Example

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{ "Status" : "FAILED", "Reason" : "Required failure reason string", "RequestId" : "unique id for this update request (copied from request)", "LogicalResourceId" : "name of resource in template (copied from request)", "StackId" : "arn:aws:cloudformation:us-east-2:namespace:stack/stack-name/guid (copied from request)", "PhysicalResourceId" : "custom resource provider-defined physical id" }

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