Question

A team deploys a serverless application using AWS SAM. The same application is deployed to 'dev', 'staging', and 'prod' environments, each represented by a separate API Gateway stage. The Lambda function behind the API must call a different downstream service endpoint depending on the stage it is invoked from, WITHOUT redeploying separate copies of the function code for each environment. What is the recommended approach to pass the correct endpoint value to the Lambda function per stage?

Accepted Answer

Define API Gateway stage variables for each stage and map them into the Lambda integration request so the function receives the correct endpoint at invocation time.

Answer

Hardcode all three endpoints in the Lambda code and use an if/else block based on the AWS_REGION environment variable to select the endpoint.

Answer

Set a single Lambda environment variable in the SAM template Globals section so all stages share the same endpoint value.

Answer

Create three separate Lambda functions, one per environment, each with its own environment variable, and route each API Gateway stage to its dedicated function.