class aws_cdk.core.CustomResource(scope, id, *, service_token, pascal_case_properties=None, properties=None, removal_policy=None, resource_type=None)

Bases: Resource

Instantiation of a custom resource, whose implementation is provided a Provider.

This class is intended to be used by construct library authors. Application builder should not be able to tell whether or not a construct is backed by a custom resource, and so the use of this class should be invisible.

Instead, construct library authors declare a custom construct that hides the choice of provider, and accepts a strongly-typed properties object with the properties your provider accepts.

Your custom resource provider (identified by the serviceToken property) can be one of 4 constructs:

  • If you are authoring a construct library or application, we recommend you use the Provider class in the custom-resources module.

  • If you are authoring a construct for the CDK’s AWS Construct Library, you should use the CustomResourceProvider construct in this package.

  • If you want full control over the provider, you can always directly use a Lambda Function or SNS Topic by passing the ARN into serviceToken.






service_token = CustomResourceProvider.get_or_create(self, "Custom::MyCustomResourceType",
    description="Lambda function created by the custom resource provider"

CustomResource(self, "MyResource",
  • scope (Construct) –

  • id (str) –

  • service_token (str) – The ARN of the provider which implements this custom resource type. You can implement a provider by listening to raw AWS CloudFormation events and specify the ARN of an SNS topic (topic.topicArn) or the ARN of an AWS Lambda function (lambda.functionArn) or use the CDK’s custom resource provider framework which makes it easier to implement robust providers. Provider framework:: // use the provider framework from aws-cdk/custom-resources: const provider = new customresources.Provider(this, ‘ResourceProvider’, { onEventHandler, isCompleteHandler, // optional }); new CustomResource(this, ‘MyResource’, { serviceToken: provider.serviceToken, }); AWS Lambda function:: // invoke an AWS Lambda function when a lifecycle event occurs: new CustomResource(this, ‘MyResource’, { serviceToken: myFunction.functionArn, }); SNS topic:: // publish lifecycle events to an SNS topic: new CustomResource(this, ‘MyResource’, { serviceToken: myTopic.topicArn, });

  • pascal_case_properties (Optional[bool]) – Convert all property keys to pascal case. Default: false

  • properties (Optional[Mapping[str, Any]]) – Properties to pass to the Lambda. Default: - No properties.

  • removal_policy (Optional[RemovalPolicy]) – The policy to apply when this resource is removed from the application. Default: cdk.RemovalPolicy.Destroy

  • resource_type (Optional[str]) – For custom resources, you can specify AWS::CloudFormation::CustomResource (the default) as the resource type, or you can specify your own resource type name. For example, you can use “Custom::MyCustomResourceTypeName”. Custom resource type names must begin with “Custom::” and can include alphanumeric characters and the following characters: _@-. You can specify a custom resource type name up to a maximum length of 60 characters. You cannot change the type during an update. Using your own resource type names helps you quickly differentiate the types of custom resources in your stack. For example, if you had two custom resources that conduct two different ping tests, you could name their type as Custom::PingTester to make them easily identifiable as ping testers (instead of using AWS::CloudFormation::CustomResource). Default: - AWS::CloudFormation::CustomResource



Apply the given removal policy to this resource.

The Removal Policy controls what happens to this resource when it stops being managed by CloudFormation, either because you’ve removed it from the CDK application or because you’ve made a change that requires the resource to be replaced.

The resource can be deleted (RemovalPolicy.DESTROY), or left in your AWS account for data recovery and cleanup later (RemovalPolicy.RETAIN).


policy (RemovalPolicy) –

Return type



Returns the value of an attribute of the custom resource of an arbitrary type.

Attributes are returned from the custom resource provider through the Data map where the key is the attribute name.


attribute_name (str) – the name of the attribute.

Return type



a token for Fn::GetAtt. Use Token.asXxx to encode the returned Reference as a specific type or use the convenience getAttString for string attributes.


Returns the value of an attribute of the custom resource of type string.

Attributes are returned from the custom resource provider through the Data map where the key is the attribute name.


attribute_name (str) – the name of the attribute.

Return type



a token for Fn::GetAtt encoded as a string.


Returns a string representation of this construct.

Return type




The environment this resource belongs to.

For resources that are created and managed by the CDK (generally, those created by creating new class instances like Role, Bucket, etc.), this is always the same as the environment of the stack they belong to; however, for imported resources (those obtained from static methods like fromRoleArn, fromBucketName, etc.), that might be different than the stack they were imported into.


The construct tree node associated with this construct.


The physical name of this custom resource.


The stack in which this resource is defined.

Static Methods

classmethod is_construct(x)

Return whether the given object is a Construct.


x (Any) –

Return type


classmethod is_resource(construct)

Check whether the given construct is a Resource.


construct (IConstruct) –

Return type