state-machine-cr-provider

StateMachineCustomResourceProvider

Implement custom resources with AWS Step Functions state machines.

The StateMachineCustomResourceProvider allows to create complex custom resources calling various AWS services and running long processes. This with minimal runtime code.

For example, it can be used to run a Fargate task to provision a RDS database.

Usage

Define a StateMachineCustomResourceProvider and pass its serviceToken to a a cdk.CustomResource.

import { CustomResource, Stack, StackProps } from 'aws-cdk-lib';
import * as cloudstructs from 'cloudstructs';
import { Construct } from 'constructs';

export class MyStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);

    // Define a provider
    const provider = new cloudstructs.StateMachineCustomResourceProvider(this, 'Provider', {
      stateMachine: myStateMachine,
    });

    // Use the provider as a custom resource
    new CustomResource(this, 'CustomResource', {
      serviceToken: provider.serviceToken,
      properties: {
        Key: 'value',
      },
    });
  }
}

The provider will start an execution of myStateMachine with the custom resource request object.

The provider automatically sends back a response to CloudFormation and handles errors in case of failures or timeouts. This prevent deployments from being blocked.

The following fields can be specified in the execution output of myStateMachine:

• PhysicalResourceId: The allocated/assigned physical ID of the resource. If omitted for Create events, the event's RequestId will be used. For Update, the current physical ID will be used. If a different value is returned, CloudFormation will follow with a subsequent Delete for the previous ID (resource replacement). For Delete, it will always return the current physical resource ID.

• Data: Resource attributes, which can later be retrieved through Fn::GetAtt on the custom resource object.

• NoEcho: Indicates whether to mask the output of the custom resource when retrieved by using the Fn::GetAtt function. The default value is false.