Running .NET on AWS Lambda: A Quick Start Guide

Amazon Web Services (AWS) Lambda is a serverless compute service that lets you run code without provisioning or managing servers. With support for .NET, you can build Lambda functions in C# and deploy them seamlessly. In this guide, you'll learn how to create, build, and deploy a .NET Lambda function using the AWS .NET tooling.

Prerequisites

Before you start, make sure you have:

• .NET SDK 6.0 or later

• AWS CLI (configured with credentials)

• Amazon.Lambda.Tools

• An AWS account

Install the Lambda tooling with:

dotnet tool install -g Amazon.Lambda.Tools

Step 1: Create a Lambda Project

You can create a new Lambda project using one of the AWS templates:

dotnet new lambda.EmptyFunction --name MyLambdaFunction
cd MyLambdaFunction

The main function logic will be in Function.cs, under the method FunctionHandler.

Step 2: Write Your Function Logic

Edit Function.cs to match your logic. For example:

public class Function
{
    public string FunctionHandler(string input, ILambdaContext context)
    {
        return $"Hello, {input}!";
    }
}

Step 3: Test Locally

You can test the function locally with:

dotnet lambda invoke-function MyLambdaFunction --payload "World"

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Step 4: Deploy to AWS

Deploy using the Lambda tools:

dotnet lambda deploy-function MyLambdaFunction

You’ll be prompted for details like the IAM role, region, and function name. You can also use --function-role, --region, and other flags to script deployments.

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Step 5: Invoke from AWS Console or API

Once deployed, you can:

• Test it from the AWS Lambda Console

• Invoke it using the AWS CLI:

aws lambda invoke \
  --function-name MyLambdaFunction \
  --payload "\"John Doe\"" \
  output.json

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Optional: Set Up API Gateway

To expose your Lambda via HTTP, connect it to API Gateway:

• In the AWS Console, go to API Gateway.

• Create a new HTTP API.

• Add an integration with your Lambda.

• Deploy the API and use the URL to invoke your Lambda.

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Cleanup

To delete the Lambda and avoid charges:

aws lambda delete-function --function-name MyLambdaFunction

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Conclusion

Running .NET on AWS Lambda is a great way to take advantage of serverless architecture while using C#. With a few CLI commands, you can deploy scalable functions to the cloud without managing infrastructure.

Need advanced patterns, like dependency injection, configuration, or async I/O? AWS .NET Lambda projects support all of them. Let me know if you want a follow-up post on those topics.

References

• AWS Lambda for .NET
  https://docs.aws.amazon.com/lambda/latest/dg/dotnet.html

• AWS Toolkit for .NET CLI (Amazon.Lambda.Tools)
  https://github.com/aws/aws-extensions-for-dotnet-cli

• .NET Templates for AWS Lambda
  https://docs.aws.amazon.com/lambda/latest/dg/csharp-package-cli.html

• Deploying .NET Lambda Functions
  https://docs.aws.amazon.com/lambda/latest/dg/csharp-deployment-package.html

• Testing AWS Lambda Functions Locally
  https://docs.aws.amazon.com/lambda/latest/dg/images-test.html

• AWS Lambda + API Gateway Integration
  https://docs.aws.amazon.com/apigateway/latest/developerguide/apigateway-getting-started-with-rest-apis.html

• .NET on AWS – Official AWS Page
  https://aws.amazon.com/net/