AWS ADOT Java Lambda Not Sending Data to OTEL Collector

[papystanny]

Hi everyone,

I'm working on an AWS Lambda function in Java that collects logs, traces, and metrics and sends them to an OpenTelemetry (OTEL auto-instrumentattion ) collector running on-premise (Docker OTEL contrib container). From there, the OTEL collector should forward the data to Datadog.

I am using AWS Distro for OpenTelemetry (ADOT) following the documentation:
🔗 ADOT Lambda Java Setup
🔗 AWS ADOT Official Page

My Lambda runs successfully without errors, but I don't see any telemetry data reaching the OTEL collector.

Lambda Setup
Runtime: Java 21
Build Tool: Maven
ARN Used: arn:aws:lambda:ca-central-1:901920570463:layer:aws-otel-java-wrapper-amd64-ver-1-32-0:4

Environment Variables Configured:
AWS_LAMBDA_EXEC_WRAPPER /opt/otel-handler
OTEL_EXPORTER_OTLP_ENDPOINT http://8.tcp.ngrok.io:18215 ( the endpoint is reachable, i tried with external tool)

Lambda Code

package com.example;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import io.opentelemetry.api.GlobalOpenTelemetry;
import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.Tracer;

public class MyLambdaHandler implements RequestHandler<String, String> {
    private static final Tracer tracer = GlobalOpenTelemetry.getTracer("com.example.MyLambdaHandler");

    @Override
    public String handleRequest(String input, Context context) {
        context.getLogger().log("Lambda execution started...");

        // ✅ Create an OpenTelemetry trace
        Span span = tracer.spanBuilder("Lambda Execution").startSpan();
        try {
            span.setAttribute("input.value", input);
            System.out.println("✅ Trace recorded with OpenTelemetry");
        } finally {
            span.end(); // ✅ End the trace
        }

        return "Hello, " + input + "! This is a Lambda function in Java 21.";
    }
}

Issue Details
✅ Lambda executes without errors.
❌ No logs, traces, or metrics appear in the OTEL collector logs.
❌ The OTEL collector does not receive any data from Lambda.

Questions
Are my environment variables correctly set for ADOT Java Lambda?
Does ADOT Java Lambda require additional configuration to send traces/metrics?
Any recommendations to debug why the telemetry data is not being sent?

Thank you in advance !