AWS Lambda logs in context of traces

This page describes how to include TraceId and SpanId information in user-generated log messages. This way, you can associate log messages with the surrounding trace.

Prerequisites

Set up AWS Lambda log collection or AWS log forwarding.
Enable OpenTelemetry interoperability for the Lambda function.
The log output generated by the AWS Lambda function must be formatted so that the TraceId and SpanId information can be picked up. The expected format of the enriched fields in an unstructured log is as follows:
- Encapsulated in square brackets [] with a !dt prefix
- dt.trace_id and dt.span_id must be hex-encoded strings Example: [!dt dt.trace_id=0af7651916cd43dd8448eb211c80319c,dt.span_id=00f067aa0ba902b7]

OpenTelemetry Python

In the example below, a dt_log function has been created to enrich a given log message with the trace_id and span_id information. Printing this enriched message to stdout associates the log message with the currently active span in the Dynatrace web UI.

python
from opentelemetry import trace

def dt_log(msg):
  ctx = trace.get_current_span().get_span_context()
  trace_id = format(ctx.trace_id, "032x")
  span_id =  format(ctx.span_id, "016x")
  print("[!dt dt.trace_id={},dt.span_id={}] - {}".format(trace_id, span_id, msg));

def lambda_handler(event, context):
  msg = "Hello from AWS Lambda Python"

  dt_log(msg)

  return {
      "statusCode": 200,
      "body": msg
  }

OpenTelemetry JavaScript (Node.js)

javascript
const opentelemetry = require('@opentelemetry/api');

function dtLog(msg) {
  let current_span = opentelemetry.trace.getSpan(opentelemetry.context.active());
  let trace_id = current_span.spanContext().traceId;
  let span_id = current_span.spanContext().spanId;
  console.log(`[!dt dt.trace_id=${trace_id},dt.span_id=${span_id}] - ${msg}`);
}

exports.handler = function(event, context) {
  let msg = "Hello from AWS Lambda Node.js"

  dtLog(msg);

  context.succeed({
    statusCode: 200,
    body: msg
  });
};

OpenTelemetry Java

In the example below, a dtLog method has been created to enrich a given log message with the TraceId and SpanId information. Printing this enriched message via System.out associates the log message with the currently active span in the Dynatrace web UI.

java
package com.amazonaws.lambda.demo;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;

import io.opentelemetry.api.trace.Span;
import io.opentelemetry.api.trace.SpanContext;

public class HelloJava implements RequestHandler<Object, String> {

  private static void dtLog(final String msg) {
    SpanContext spanContext = Span.current().getSpanContext();
    System.out.printf(
      "[!dt dt.trace_id=%s,dt.span_id=%s] - %s%n",
      spanContext.getTraceId(),
      spanContext.getSpanId(),
      msg
    );
  }

  @Override
  public String handleRequest(Object input, Context context) {
    String msg = "Hello from AWS Lambda Java";

    dtLog(msg);

    return msg;
  }
}