AWS CloudFormation Outputs and Stack Collaboration

Overview of Outputs in CloudFormation

• Outputs are optional values that can be declared in a CloudFormation template.
• They can be used to export configuration values to other stacks, allowing stack collaboration.
• Outputs can be viewed in the AWS Management Console or retrieved using the AWS CLI.
• The term "cross-stack reference" in AWS CloudFormation refers to the ability to share information between different CloudFormation stacks.

Benefits of Using Outputs

• Facilitates the reuse of resources such as VPC IDs and Subnet IDs across different stacks.
• Enables collaboration, allowing different teams to manage their respective stacks and share resources.
• Ensures that resources are properly referenced and managed across dependent stacks.

Example of Output Declaration

• A security group is created in one template.
• An output is declared that references the security group and includes an export block.
• The export block assigns a unique name to the output value, which can be used in other stacks.

Example of Output Usage

• Another CloudFormation template imports the value of the security group from the previous stack.
• The ImportValue function is used to reference the exported value by its unique name.
• The EC2 instance in the new template uses the imported security group ID.