Summary
In this chapter, we learned about custom resources, the most universal way to extend CloudFormation. We created our own CR backed by AWS Lambda, made it stable and secure, and also made it able to handle updates, deletions, and errors.
Custom resources are widely used to either create resources in AWS that are not yet supported by CloudFormation or create resources outside of AWS, whether they are other cloud platforms or your own platforms and systems running on EC2.
We covered custom resources and provisioning logic and understood what actually happens under the hood. To get a real hands-on experience with CRs, we developed our own CR, made it error resistant, and added support for custom reason messages.
In the next chapter we will learn about another extension of CloudFormation called the template macro. Stay tuned!
