AWS SAM CLI adds AWS CloudFormation Language Extensions support to accelerate local serverless development

AWS has updated its SAM CLI (Serverless Application Model Command Line Interface) to support AWS CloudFormation Language Extensions, addressing a longstanding limitation that forced developers to choose between template efficiency and local development capabilities. The enhancement allows developers to use CloudFormation's Fn::ForEach and other language extensions to define multiple similar resources from a single template definition while maintaining full local testing and development workflows through SAM CLI commands. Previously, developers using SAM CLI for local serverless development could not process templates containing CloudFormation Language Extensions, which are commonly used to reduce code duplication when defining multiple similar resources like Lambda functions, DynamoDB tables, or SNS topics. The new capability processes Language Extensions in memory during local operations while preserving the original template structure for CloudFormation deployment, enabling developers to catch syntax errors and missing dependencies before cloud deployment. The feature is immediately available with the latest SAM CLI version and works across all major SAM commands including sam build, sam local invoke, sam sync, and sam local start-api. Developers can now add the AWS::LanguageExtensions transform to their SAM templates and use functions like Fn::ForEach to generate resources programmatically, with SAM CLI automatically expanding loops and processing each generated resource during local development cycles.