Resolving Cross-Region Stack References in AWS CDK
ERROR: Cross-stack references are only supported for stacks deployed to the same environment or between nested stacks and their parent stack. Set crossRegionReferences=true to enable cross-region references.
When working with AWS Cloud Development Kit (CDK), it’s common to encounter situations where resources from different stacks, possibly in different regions, need to reference each other. A typical error message you might come across is:
Error: Stack ‘Stack1’ cannot reference {Stack2/KmsKey/Resource[Arn]}
in stack ‘Stack2’. Cross-stack references are only supported for stacks
deployed to the same environment or between nested stacks and their parent stack.
Set crossRegionReferences=true to enable cross-region references.This article explains the issue and provides a straightforward solution to enable cross-region references between stacks in AWS CDK.
Understanding the Issue
By default, AWS CDK supports references (e.g., outputs, SSM parameters) only between stacks that are deployed within the same AWS region or between nested stacks and their parent stack. This limitation exists to prevent complexities and potential inconsistencies arising from managing resources across different geographic locations.
However, in a multi-region AWS architecture, you might need to reference resources across regions. For example, a KMS key created in one region might need to be accessed by resources in another region.
Solution: Enabling Cross-Region References
AWS CDK offers a property crossRegionReferences: true within the stack properties to overcome this limitation. By setting this property to true, you instruct CDK to allow resources in one stack to reference resources in another stack, even if they are in different regions.
How to Apply the Solution
To implement cross-region references, you need to modify the stack properties in your CDK code. Below is an example that demonstrates how to enable cross-region references for two stacks:
Define Stack 1 (Primary Stack):
This stack is deployed in the primary region and might contain resources that need to be accessed by another stack in a different region.
const stack1 = new Stack(app, 'Stack1', {
env: { region: 'us-east-1' },
// Other stack properties
});Define Stack 2 (Secondary Stack)
This stack is deployed in a secondary region and needs to access resources from Stack 1.
To enable cross-region references, add crossRegionReferences: true in the stack properties:
const stack2 = new Stack(app, 'Stack2', {
env: { region: 'eu-west-1' },
crossRegionReferences: true, // Enable cross-region references
// Other stack properties
});By setting crossRegionReferences: true in the secondary stack, you enable it to reference resources from the primary stack, regardless of the region. This solution simplifies the management of multi-region architectures in AWS CDK.
For more detailed information and advanced configurations, refer to the AWS CDK documentation and community discussions, such as those on Stack Overflow.
