Create - AWS CloudFormation
RequestResponses

Create

When the template developer creates a stack containing a custom resource, CloudFormation sends a request to the custom resource provider with RequestType set to Create. This request happens specifically when the custom resource is being created.

For an introduction to custom resources and how they work, see Create custom provisioning logic with custom resources.

Request

Create requests contain the following fields:

RequestType

Create.

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 CloudFormation template. Custom resource type names can be up to 60 characters long and can include alphanumeric and the following characters: _@-.

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.

ResourceProperties

This field contains the contents of the Properties object sent by the template developer. Its contents are defined by the custom resource provider.

Example

{
   "RequestType" : "Create",
   "RequestId" : "unique id for this create request",
   "ResponseURL" : "pre-signed-url-for-create-response",
   "ResourceType" : "Custom::MyCustomResourceType",
   "LogicalResourceId" : "name of resource in template",
   "StackId" : "arn:aws:cloudformation:us-west-2:123456789012:stack/mystack/5b918d10-cd98-11ea-90d5-0a9cd3354c10",
   "ResourceProperties" : {
      "key1" : "string",
      "key2" : [ "list" ],
      "key3" : { "key4" : "map" }
   }
}

Responses

Success

When the create request is successful, a response must be sent to the Amazon S3 bucket with the following fields:

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.

The value returned for a PhysicalResourceId can change custom resource update operations. If the value returned is the same, it is considered a normal update. If the value returned is different, AWS CloudFormation recognizes the update as a replacement and sends a delete request to the old resource. For more information, see AWS::CloudFormation::CustomResource.

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 (*****), except for those stored in the Metadata section of the template. AWS CloudFormation does not transform, modify, or redact any information you include in the Metadata section. The default value is false.

For more information about using NoEcho to mask sensitive information, see the Do not embed credentials in your templates best practice.

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

{
   "Status" : "SUCCESS",
   "RequestId" : "unique id for this create request (copied from request)",
   "LogicalResourceId" : "name of resource in template (copied from request)",
   "StackId" : "arn:aws:cloudformation:us-west-2:123456789012:stack/mystack/5b918d10-cd98-11ea-90d5-0a9cd3354c10 (copied from request)",
   "PhysicalResourceId" : "required vendor-defined physical id that is unique for that vendor",
   "Data" : {
      "keyThatCanBeUsedInGetAtt1" : "data for key 1",
      "keyThatCanBeUsedInGetAtt2" : "data for key 2"
   }
}

Failed

When the create request fails, a response must be sent to the S3 bucket with the following fields:

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.

The value returned for a PhysicalResourceId can change custom resource update operations. If the value returned is the same, it is considered a normal update. If the value returned is different, AWS CloudFormation recognizes the update as a replacement and sends a delete request to the old resource. For more information, see AWS::CloudFormation::CustomResource.

Example

{
   "Status" : "FAILED",
   "Reason" : "Required failure reason string",
   "RequestId" : "unique id for this create request (copied from request)",
   "LogicalResourceId" : "name of resource in template (copied from request)",
   "StackId" : "arn:aws:cloudformation:us-west-2:123456789012:stack/mystack/5b918d10-cd98-11ea-90d5-0a9cd3354c10 (copied from request)",
   "PhysicalResourceId" : "required vendor-defined physical id that is unique for that vendor"
}