Developing Amazon Lambda function scripts on my local machine is a hassle. There are work-arounds, but it required me to write dirty, ad-hoc code. So I took some time to develop a node commandline tool called Lambda-local , that’ll execute your Lambda functions on your local machine, with whatever sample event data you want to feed it.

Just install with

npm install -g lambda-local

and use it with

lambda-local -l index.js -h handler -e event_samples/s3-put.js

You can feed any even data (JSON object) into the -e option.
I also added a -t (--timeout) option which let’s you set your own timeout limit in seconds.


The goal of this script is for devleopers to not have to write even 1 line of extra code in order to run their Lambda functions on their local machine. I thought it should all be handled by a simple command.
My further goal is to emulate whatever environment Amazon has set up on their Lambda console - Which includes:

  • Feeding sample event data
  • Setting a timeout limit
  • Setting a memory limit

I have two out of three (although the timeout part is still pretty rought). I want to try and implement a memory limit, maybe even just a warning.

Things I want to fix

Since the AWS console lets you load the aws-sdk module without installation, I wanted to emulate that.
The only solution I have now is to add Lambda-local’s node_modules path to the $NODE_PATH env variable, as well as your AWS credentials.
It would be great if I can have the lambda-local handle that automatically, but currently the users have to export manually.
I wish there is a better solution for this.

Personally I think Amazon Lambda has a great amount of potential, so I believe it’s important to have a dead-easy development environment for it, rather than having to upload your script/zip everytime. Hell, you don’t even have to sign up for Lambda to play with Lambda.

If AWS comes out with their own Lambda-local tool this will become obsolete, but until then, it’s a simple & independent tool that doesn’t require any learning curves and any additional code/configuration on your existing Lambda function scripts. I think it’s not too bad for a start.

So please try it out, fork it, or give me any feedback!

P.S. This was also my first time to write and publish a npm module. It was quite fun, and the publishing process is surprisingly easy. I really like it :)