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The Benefits and Limitations of CloudFormation Nested Stacks

Creating robust and scalable infrastructures in AWS requires proper planning and management of resources. AWS CloudFormation is an AWS service that allows you to define your infrastructure as code. This means you can use code to create, update, or delete your infrastructure resources in a repeatable and predictable manner. CloudFormation is a very powerful tool that can help you manage your infrastructure efficiently, and one of the features that makes it so powerful is Nested Stacks. In this post, we will discuss the benefits and limitations of using CloudFormation Nested Stacks.

What are Nested Stacks in CloudFormation?

Nested Stacks are CloudFormation stacks that are created from within another CloudFormation stack. This means you can create a CloudFormation stack that contains other CloudFormation stacks. This is useful when you want to break down your infrastructure into smaller, more manageable pieces.

Benefits of Using Nested Stacks

• Modular Infrastructure: Nested Stacks help you build a modular infrastructure with reusable components. You can use the same Nested Stack in multiple CloudFormation stacks, eliminating duplication of code and configuration.

• Reduced Stack Complexity: Using Nested Stacks, you can separate complex resources and configurations from the main stack. This helps to reduce the complexity of the main stack, making it easier to read and manage.

• Parallel Creation and Deletion: Nested Stacks can be created and deleted in parallel, which speeds up the creation and tear-down of your infrastructure. This is because CloudFormation creates each Nested Stack as a separate CloudFormation stack.

• Failure Isolation: Nested Stacks allow you to isolate failures to a specific area of your infrastructure. If a Nested Stack fails to create or delete, it will not affect the other stacks in the main CloudFormation stack.

Limitations of Using Nested Stacks

• Increased Management Overhead: Using Nested Stacks can increase management overhead as you need to manage the lifecycle of each stack separately. This can include tasks such as updating the stack, monitoring its status, and troubleshooting issues.

• Limits on the Number of Nested Stacks: AWS imposes a limit on the number of nested stacks that you can create within a root stack. This limit is fixed at 1000 stacks per root stack. This limit can be increased, but it requires you to reach out to AWS support.

• Increased Complexity of Stack Dependencies: As the number of Nested Stacks increases, so does the complexity of the stack dependencies. This can be challenging to manage, especially when creating or deleting stacks.

• Costs: Using Nested Stacks can incur additional costs as each Nested Stack is treated as a separate stack in CloudFormation. This means you pay for the resources used in each Nested Stack as well as the main stack.

Conclusion

Nested Stacks are a powerful feature of AWS CloudFormation that can help you build modular infrastructures. They can reduce the complexity of the main stack, allowing for better organization and management. However, they do come with some limitations, such as increased management overhead and potential for increased costs. It's important to weigh the benefits against the limitations before deciding if Nested Stacks are the right approach for your infrastructure.

We hope this article has helped you understand the benefits and limitations of using CloudFormation Nested Stacks. If you have any suggestions, please let us know in the comments section below.