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AWS Lambda with .NET Functions

Learn how to build and deploy serverless .NET functions using AWS Lambda.

By EMEPublished: February 20, 2025
awslambdaserverlessdotnetcloudfunctions

A Simple Analogy

Imagine a light switch that only turns on when you need it. AWS Lambda is like that switch—it runs your code only when something happens (an event), then turns off to save energy and cost. You don't need to worry about the wiring or the power company; AWS handles all the infrastructure for you.

What Is AWS Lambda?

AWS Lambda is a serverless compute service that lets you run code in response to events (HTTP requests, file uploads, database changes) without managing servers. You pay only for the time your code runs.

With .NET, you can write Lambda functions in C# or F#, package them, and deploy to AWS.

Why Use Lambda Functions?

  • No servers to manage: AWS handles scaling, patching, and availability.
  • Cost-effective: Pay only for actual usage (per millisecond).
  • Event-driven: Trigger code from many AWS services (API Gateway, S3, DynamoDB, etc.).
  • Scalable: Automatically handles thousands of requests in parallel.
  • Fast deployments: Update code quickly without downtime.

How to Build .NET Lambda Functions

1. Create a Lambda Project

dotnet new lambda.EmptyFunction -n MyLambdaFunction

2. Write Your Handler

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

3. Deploy to AWS

dotnet tool install -g Amazon.Lambda.Tools
dotnet lambda deploy-function MyLambdaFunction

4. Trigger from API Gateway

  • Create an API Gateway endpoint
  • Connect it to your Lambda function
  • Send HTTP requests to invoke your code

Practical Examples

  • RESTful APIs: Handle HTTP requests with Lambda and API Gateway
  • Image processing: Resize or analyze images uploaded to S3
  • Scheduled tasks: Run code on a timer (CloudWatch Events)
  • Data transformation: Process DynamoDB streams or Kinesis events
  • Notifications: Send emails or push notifications when events occur

Real-World Use Cases

  • E-commerce: Order processing, payment notifications
  • IoT: Device telemetry ingestion and analysis
  • Analytics: Real-time data aggregation
  • DevOps: Automated deployment and monitoring scripts
  • Chatbots: Respond to user messages instantly

Best Practices

  • Keep functions small and focused (single responsibility)
  • Use environment variables for configuration
  • Monitor with AWS CloudWatch (logs, metrics, alarms)
  • Secure with IAM roles and policies
  • Optimize cold start times (minimize dependencies)
  • Test locally before deploying
  • Use layers for shared code/libraries

Related Concepts to Explore

  • AWS API Gateway
  • Serverless Frameworks (SAM, Serverless.com)
  • Event-driven architecture
  • AWS Step Functions (workflows)
  • CloudWatch monitoring
  • IAM roles and permissions
  • S3 triggers and event sources
  • Azure Functions and Google Cloud Functions
  • Container-based Lambda (with .NET)
  • Lambda Layers and deployment packages

Summary

AWS Lambda lets you run .NET code in the cloud without managing servers. It's perfect for event-driven, scalable, and cost-effective solutions—whether you're building APIs, automating tasks, or processing data in real time.