How to detect if I'm running in AWS Lambda environment?

Question

I want to detect if my code is getting executed in AWS Lambda environment. Is there a good, documented way to do it?

Currently I'm depending on existence of environmental variable LAMBDA_TASK_ROOT which was described in the Exploring The AWS Lambda Runtime Environment blog post which feels wrong.

Answer 1

There is a process.env property that you can check:

const isLambda = !!process.env.LAMBDA_TASK_ROOT;

if (isLambda) {
  // You're on AWS Lambda
} else {
  // Local or elsewhere
}

Credit to watson/is-lambda for the discovery.

Edit: Official AWS source (with more env vars) https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html