AWS Serverless Application Model (AWS SAM) now supports WebSocket APIs for Amazon API Gateway, enabling you to define complete WebSocket APIs with minimal configuration in your SAM template.

AWS SAM is a collection of open-source tools that make it easy for you to build and manage serverless applications. WebSocket APIs are critical for real-time applications such as chat, live dashboards, AI/LLM streaming, and IoT. However, SAM previously did not support WebSocket APIs, requiring you to manually configure all of the underlying resources in AWS CloudFormation. This made it difficult to debug common issues such as missing IAM permissions for Lambda functions. Now, SAM handles all of this automatically, generating the required resources and permissions from your template. The new resource provides feature parity with API Gateway WebSocket APIs, including IAM and Lambda authorization, custom domains, RouteSettings, Models, and StageVariables. Globals support lets you share common configuration across multiple WebSocket APIs.

To get started, add the AWS::Serverless::WebSocketApi resource type to your SAM template. Define your routes by specifying Lambda function handlers for $connect, $disconnect, and $default routes, along with any custom routes your application requires. SAM automatically wires up the integrations and permissions for each route. You can also configure authorization, stage settings, and custom domains directly within the resource definition.

To learn more, visit the SAM developer guide.