How can I know whether it is running inside lambda?

Question

I am deploying nodejs code to AWS lambda and I'd like to know how I can check whether it is running in lambda. Because I need to do something different in code between lambda and local.

Answer 1

AWS Lambda sets various runtime environment variables that you can leverage. You can use the following in Node.js, for example:

const isLambda = !!process.env.LAMBDA_TASK_ROOT;
console.log("Running on Lambda:", isLambda);

Note that the double bang !! converts a truthy/falsey object to a boolean (true/false).

Answer 2

I'd advise using a Lambda environment variable rather than attempting to check against any runtimes of the Lambda executing.

By doing this you can ensure that any infrastructure changes on the AWS side of Lambda will not affect your code.

It also allows you test it locally if you are trying to reproduce a scenario without the need to hardcode logic.