Library for testing an AWS lambda locally with C#

Recently I’ve been working on a library that will allow you to run an AWS lambda locally, as you would within an API Gateway. This is really useful for testing as if it were a real lambda, and has helped me out massively!

It works by standing up a web server (kestrel) which will proxy the incoming request into an ApiGatewayRequest and forward onto the instance of your lambda, with the context sending output to the console.

Setup

First of all, you will need to create a sperate project, to host the lambda, so create a new Console Application.

In the package manager console, install the library using the command install-package lambda-local-harness

In your console application you will want to new up the LambdaHost and Wait, similar to:

class Program
{
        static void Main(string[] args)
        {
            Ioc.IocSetup();
            var function = new Function(Ioc.Resolve<IApplicationValidator>(), new TelemetryClient());

            using (var host = new LambdaHost(function, nameof(Function.FullApplication), new Dictionary<string, string>()))
            {
                host.Wait();
            }
      }
}

Once setup and run, you can send requests to the lambda, and test your lambda, debugging support etc.

If you want more information, checkout the github repo: https://github.com/craiggoddenpayne/lambda-local-harness