Building Serverless Apps with .NET 8 and AWS Lambda - Made Simple

The way we build apps in the cloud is changing. With serverless architecture like AWS Lambda, we’re no longer managing infrastructure. And with .NET 8, C# developers now have the tools to run apps faster, lighter, and smarter in that environment.

Over the last few weeks, I explored what it’s like building serverless Lambda functions with .NET 8, using Minimal APIs and Native AOT (ahead-of-time compilation). What started as an experiment turned into a surprisingly fast, developer-friendly, and cost-effective workflow - and in this post, I’ll walk you through how to do the same.

Why Serverless with .NET 8?

AWS Lambda is built for simplicity - short-lived tasks, triggered by events, scaled automatically. It’s been hugely popular in the JavaScript and Python ecosystems. But for .NET? Not always.

That’s now changed. .NET 8 brings:

1. Native AOT (Ahead-of-Time Compilation)

• Compiles your app into a native binary
• Starts up fast - ideal for serverless

2. Minimal APIs

• No controllers, no startup classes
• Clean, modern syntax with fewer lines of code

3. Official AWS Support

• Lambda templates for .NET 8
• Easy deployment with the AWS CLI and Toolkit

This isn’t just theory - I built and benchmarked it.

Step-by-Step Setup: Create a .NET 8 Lambda Function from Scratch

Open PowerShell or your terminal. Here’s exactly what I did (generic folder structure so you can follow along

1. Install Lambda templates (if you haven’t)

dotnet new install Amazon.Lambda.Templates        

2. Create the Lambda function

dotnet new lambda.EmptyFunction --name DemoLambda
cd DemoLambda        

3. Create and set up a solution

dotnet new sln -n DemoLambda
dotnet sln add src/DemoLambda/DemoLambda.csproj        

4. Add any packages (e.g., SQL client)

cd src/DemoLambda
dotnet add package System.Data.SqlClient        

5. Build and test

dotnet build        

Optional : add a test project to validate your logic and build it as well:

dotnet build "test/DemoLambda.Tests/"        

Enable Native AOT for Speed

Update your .csproj file like this:

<PropertyGroup>
  <TargetFramework>net8.0</TargetFramework>
  <RuntimeIdentifier>linux-x64</RuntimeIdentifier>
  <SelfContained>true</SelfContained>
  <PublishAot>true</PublishAot>
  <StripDebugSymbols>true</StripDebugSymbols>
  <InvariantGlobalization>true</InvariantGlobalization>
  <AWSProjectType>Lambda</AWSProjectType>
</PropertyGroup>        

Then publish your app:

dotnet publish -c Release -r linux-x64 --self-contained true /p:PublishAot=true        

This compiles your app into a small, native executable. Lambda loves this - it starts your function faster.

Tips and Best Practices

• Trim your build output. AOT builds can be big. Use flags like StripDebugSymbols and remove unused packages.
• No reflection. AOT can’t handle dynamic reflection well. Avoid libraries that depend heavily on it.
• Add good logs. Error messages are minimal in native builds. Use structured logging to help with debugging.
• Test cold starts. Deploy and test from a cold start, not just local warm runs.

Use Cases Where This Shines

• REST APIs
• Cognito triggers (like pre-auth)
• Background jobs
• SQS / SNS / S3 event handlers

Not ideal for:

• Heavy, long-running workflows
• Apps with complex dynamic behavior or reflection
• In-memory caching that relies on warm state

In Summary

I’ve worked with AWS Lambda, but this was my first serious run at it with .NET 8. I didn’t expect it to be this smooth.

• Native AOT makes C# feel fast in the cloud.
• Minimal APIs make code easier to read, write, and maintain.
• AWS has done a great job bringing .NET into the serverless world.

If you’re a .NET developer and haven’t tried Lambda recently, you’re missing out. The combination is modern, efficient, and production-ready.

Share this if it helped, or drop a comment with your Lambda + .NET stories.

Let’s build smarter.

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