Configure response header mappings to pass ADRUM_n headers back to the browser. You can configure response header mappings:

• Using the AWS API Gateway
• Passing directly via AWS Lambda Proxy Integration
• Returning EUM metadata in your function code

Response Header Mappings in Amazon API Gateway

Add header mappings for each ADRUM_n header in the Amazon API Gateway. See Amazon API Gateway API request and response data mapping reference.

The table below lists the required response headers and their mapping values:

Response Header Mappings in AWS Lambda Proxy Integration

As an alternative to custom integration, AWS Lambda proxy integration allows the client to call each function in the backend and returns output in a JSON format. Map these responses by adding each single-value ADRUM_n header directly to the headers field in your output object class. Refer to the Amazon documentation for details.

Response Header Mappings for All Other Invocations

To gather EUM metadata, you need to configure response header mappings. This code sample invokes an appDEumHeaders method on the tracer. This method returns an object containing the ADRUM_n headers. Pass this object to the downstream service for consumption by the downstream JavaScript Agent.

The code snippet below demonstrates how you can return EUM metadata:

module.exports.myLambdaHandler = function (event, context, callback) {
setTimeout(function () {
////Call a transaction object
let appDBusinessTxn = tracer.getCurrentTransaction();
//Stop the transaction
tracer.stopTransaction();
//Return EUM Metadata
let appDEumHeaders = tracer.getEumMetadata(appDBusinessTxn);
callback(null, {
eumMetadata: appDEumHeaders,
data: 'Call to Lambda is a success'
});
}, 300);
}