You need to deploy an AWS stack in a repeatable manner across multiple environments. You have selected CloudFormation as the right tool to accomplish this. You have found that there is a resource type you need to create and model, but it is unsupported by CloudFormation. How should you overcome this challenge?

Answer options:

A.Use a CloudFormation Custom Resource Template by selecting an API call to proxy for create, update, and delete actions.CloudFormation will use the AWS SDK, CLI, or API method of your choosing as the state transition function for the resource type you are modeling.
B.Submit a ticket to the AWS Forums. AWS extends CloudFormation Resource Types by releasing tooling to the AWS Labs organization on GitHub. Their response time is usually 1 day, and they complete requests within a week or two.
C.Instead of depending on CloudFormation, use Chef, Puppet, or Ansible to author Heat templates, which are declarative stack resource definitions that operate over the OpenStack hypervisor and cloud environment.
D.Create a CloudFormation Custom Resource Type by implementing create, update, and delete functionality, either by subscribing a Custom Resource Provider to an SNS topic, or by implementing the logic in AWS Lambda.

Answer – D
Custom resources enable you to write custom provisioning logic in templates that AWS CloudFormation runs anytime you create, update (if you changed the custom resource), or delete stacks. For example, you might want to include resources that aren`t available as AWS CloudFormation resource types. You can include those resources by using custom resources. That way, you can still manage all your related resources in a single stack.
Use the AWS::CloudFormation::CustomResource or Custom::String resource type to define custom resources in your templates. Custom resources require one property: the service token, which specifies where AWS CloudFormation sends requests, such as an Amazon SNS topic.
For more information on Custom Resources in Cloudformation, please visit the below URL:
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/template-custom-resources.html