Post Request with springboot4 Container hangs

[Vadym79]

I have a simple example application which uses AWS Serverless Java Container for Spring Boot 4 to store and retrieve a product from DynamoDB. You can deploy it with AWS SAM.

It works, if I use my own handler implementation for the PostProductFunction (which creates a new product, see template.yaml) like this:

PostProductFunction:
Type: AWS::Serverless::Function
Properties:
Handler: software.amazonaws.example.product.handler.StreamLambdaHandler::handleRequest

If I switch the handler to use

Handler: com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler

and activate a required MAIN_CLASS environment variable in the Globals Function section of the SAM template like this:

Globals:
Function:
.....
Environment:
Variables:
MAIN_CLASS: software.amazonaws.Application
REGION: !Sub ${AWS::Region}
JAVA_TOOL_OPTIONS: "-XX:+TieredCompilation -XX:TieredStopAtLevel=1"
PRODUCT_TABLE_NAME: !Ref ProductsTable

The POST request sent from the API Gateway with Content-Type:application/json as a HTTP Header and JSON payload { "id": 1, "name": "Print 10x13", "price": 15 } as a HTTP body runs into the 30 second timeout of the API Gateway and Lambda function even if I clearly see in the Lambda logs, that the request is executed, which means that ProductController createProduct method is sucessfully finished within a few seconds (and the product is created in the DynamoDB). I don't have any control what's happening outside of the Controller method when using the SpringDelegatingLambdaContainerHandler as a handler.

If I switch from POST to PUT in the SAM template and ProductController the behavior is the same (it hangs with the com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler handler).

I don't have such a problem with the GET request (for example GetProductByID) which finishes successfully in time.

Please help me investigate why the problem arise? Maybe I'm doing something wrong.

ADDED : I found out how to make it work. It didn't work when createProduct method of ProductController returned void and didn't have produces mime type. Now I changed both (returning String and defined text/plain as produces mime type) and it works with com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler handler as well. Still it worked with returning void and not having produces mime type for POST/PUT with AWS Serverless Java Spring Boot 3 Container and Spring Boot 3 (I cheked my working examples). The most important thing: it should work the same way regardless whether I define my own StreamHandler , which works fine with return void and without produces mime type for POST/PUT or re-use the existing com.amazonaws.serverless.proxy.spring.SpringDelegatingLambdaContainerHandler handler. So please review the issue and fix it.