AWS SAM CLI adds CloudFormation Language Extensions support

AWS SAM CLI now supports AWS CloudFormation Language Extensions, allowing developers to reduce template duplication and maintain a full local development workflow. This enables defining resources once and testing them locally across all SAM CLI commands before cloud deployment.

This feature accelerates serverless development by letting developers define resources once and iterate locally without waiting for cloud deployments. It shortens iteration cycles and reduces time spent debugging failed deployments in the cloud by catching errors like invalid syntax or missing dependencies early.

SAM CLI supports additional Language Extensions features including Fn::Length, Fn::ToJsonString, Fn::FindInMap with DefaultValue, and conditional DeletionPolicy and UpdateReplacePolicy attributes.

To use this feature, download or update SAM CLI to the latest version, add the AWS::LanguageExtensions transform to your SAM template, and use Fn::ForEach to generate multiple resources. SAM CLI commands will automatically expand loops and process generated resources, allowing invocation by expanded function name.