What is a circular dependency in AWS CloudFormation?
When Nested Stacks depend on each other.
When Resources form a Depend On loop.
When a Template references an earlier version of itself.
When a Template references a region, which references the original Template.
Explanations:
Nested stacks can indeed depend on each other, but this is not classified as a circular dependency. Circular dependencies specifically refer to situations where resources are interdependent in such a way that they create a loop, which is more accurately described in option B.
Circular dependencies in AWS CloudFormation occur when resources depend on each other in a way that creates a loop. For example, if Resource A depends on Resource B, and Resource B depends on Resource A, this creates a circular dependency that prevents the stack from being created or updated.
A template referencing an earlier version of itself does not create a circular dependency. Circular dependencies are about the interdependencies between resources within a stack, rather than between versions of the template itself.
A template referencing a region that then references the original template does not constitute a circular dependency. Circular dependencies are defined by direct interdependencies among resources within a CloudFormation stack, not by the relationship between templates and regions.
From what I’ve heard, the answer is:
When Resources form a Depend On loop.