Get started

By the end of this page you’ll have your own solution, a container running it, and a function that answers back. It takes about five minutes, or ten if Docker decides to download the internet first.

Before you start

You need the .NET 10 SDK and Docker. You don’t need an AWS account yet. The container image ships with the Lambda runtime emulator, so your laptop can pretend to be AWS for a while.

Make it yours

Install the template from NuGet.

dotnet new install CleanLambdaFunction.Template

Create a solution. The name becomes your namespace, project names and folder, so pick something you’re happy to see a lot of.
Terminal window
```
dotnet new cleanlambdafunction --name Acme.Reviews --authorName "Your Name"
cd Acme.Reviews
```
Have a look around. Everything you need is already here.
- Acme.Reviews.sln
- Dockerfile
- docker-compose.yml
- Directorysrc/
  - DirectoryApplication/ the rules, queries and validation
    …
  - DirectoryInfrastructure/ the database and repositories
    …
  - DirectoryPresentation/ the Lambda handler
    …
- Directorytests/
  - DirectoryApplication.Tests.Unit/
    …
  - DirectoryInfrastructure.Tests.Integration/
    …
  - DirectoryPresentation.Tests.Integration/
    …
Build the image and start it with sample data. Docker Compose turns the sample data on for you.
Terminal window
```
docker compose up -d --build
```

Invoke the function. The emulator listens on port 9000 and answers the same way Lambda does.

curl -X POST "http://localhost:9000/2015-03-31/functions/function/invocations" \
  -d '{"query":"global","limit":2}'

You get a page of movies back:

{
  "Items": [
    { "Id": "30fca414-247a-779e-105a-d81aa2506f58", "Title": "Assimilated global infrastructure", "ReviewCount": 1, "AverageStars": 1 },
    { "Id": "c27d6600-79a6-9346-2595-a52b7f07dc3e", "Title": "Automated global alliance", "ReviewCount": 3, "AverageStars": 3.3 }
  ],
  "TotalCount": 2
}

Yes, the movies are named by a corporate buzzword generator. Assimilated global infrastructure only got one star. Critics can be harsh.

Run the tests while you’re here.
Terminal window
```
dotnet test
```
Tidy up when you’re done.
Terminal window
```
docker compose down
```

Where to next

Run it locallyTry the other functions, switch databases and stamp a version.

Add a functionTurn an existing query into a brand new Lambda function.

Deploy to AWSPush the container image and create the function for real.

How the layers fitWhy there are three rings and who's allowed to talk to whom.