With the rise of cloud computing, developers are shifting toward serverless architectures to build highly scalable, cost-efficient, and maintenance-free applications. AWS Lambda, combined with DynamoDB, provides an excellent way to create serverless .NET 8 APIs without worrying about infrastructure management.
This article will provide a deep dive into building serverless APIs using:
- AWS Lambda – Serverless function execution.
- Amazon API Gateway – Exposing APIs securely.
- Amazon DynamoDB – NoSQL data persistence.
- .NET 8 Minimal APIs – Optimized for performance.
- AWS CDK for Infrastructure as Code (IaC).
By the end, you’ll have a fully functional serverless API, capable of handling high traffic with minimal cost. 🚀
1. Why Choose Serverless with .NET 8?
✅ Auto-scaling – Handles thousands of requests without provisioning servers.
✅ Cost-efficient – Pay only for execution time (no idle server costs).
✅ Event-driven – Respond to events in real-time.
✅ Reduced Ops – No server maintenance, patching, or scaling worries.
✅ Seamless AWS integration – Works with S3, DynamoDB, SQS, SNS, and API Gateway.
2. Setting Up a Serverless API Using AWS Lambda
Step 1: Install AWS Lambda Templates for .NET 8
First, install the AWS Lambda .NET templates:
dotnet new -i Amazon.Lambda.Templates
Step 2: Create a New AWS Lambda Function
dotnet new lambda.EmptyFunction -n ServerlessProductAPI
cd ServerlessProductAPI
This creates a basic AWS Lambda function.
3. Implementing a .NET 8 Lambda Function
Modify Function.cs to handle HTTP requests using Minimal APIs:
Step 1: Define a Product Model
public class Product
{
public string Id { get; set; }
public string Name { get; set; }
public decimal Price { get; set; }
}
Step 2: Implement the Lambda Function
using Amazon.DynamoDBv2;
using Amazon.DynamoDBv2.DataModel;
using Amazon.Lambda.APIGatewayEvents;
using Amazon.Lambda.Core;
using System.Text.Json;
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.DefaultLambdaJsonSerializer))]
public class Function
{
private readonly DynamoDBContext _dbContext;
public Function()
{
var client = new AmazonDynamoDBClient();
_dbContext = new DynamoDBContext(client);
}
public async Task<APIGatewayProxyResponse> CreateProduct(APIGatewayProxyRequest request, ILambdaContext context)
{
var product = JsonSerializer.Deserialize<Product>(request.Body);
product.Id = Guid.NewGuid().ToString();
await _dbContext.SaveAsync(product);
return new APIGatewayProxyResponse
{
StatusCode = 201,
Body = JsonSerializer.Serialize(product)
};
}
}
✅ DynamoDB integration
✅ Minimal API for fast response
✅ Event-driven execution
4. Deploying Serverless API with AWS Lambda
Step 1: Package and Deploy Lambda
Run the following command to publish your .NET 8 Lambda function:
dotnet lambda deploy-function ServerlessProductAPI
AWS will package, upload, and deploy the function.
5. Exposing Lambda via API Gateway
To make the Lambda function accessible via HTTP, set up an API Gateway.
Step 1: Create an API Gateway
aws apigateway create-rest-api --name "ProductAPI"
Step 2: Create a Resource & Method
aws apigateway create-resource --rest-api-id <api-id> --parent-id <root-id> --path-part products
aws apigateway put-method --rest-api-id <api-id> --resource-id <resource-id> --http-method POST --authorization-type NONE
Step 3: Integrate API Gateway with Lambda
aws apigateway put-integration --rest-api-id <api-id> --resource-id <resource-id> --http-method POST --type AWS_PROXY --uri "arn:aws:lambda:region:account-id:function:ServerlessProductAPI"
✅ Now, calling POST /products will invoke the Lambda function.
6. Persisting Data in DynamoDB
DynamoDB is a fully managed NoSQL database optimized for serverless applications.
Step 1: Create a DynamoDB Table
aws dynamodb create-table --table-name Products \
--attribute-definitions AttributeName=Id,AttributeType=S \
--key-schema AttributeName=Id,KeyType=HASH \
--billing-mode PAY_PER_REQUEST
Step 2: Save Data to DynamoDB
Modify CreateProduct function:
await _dbContext.SaveAsync(product);
Now, products are stored in DynamoDB.
7. Automating Deployment with AWS CDK
AWS CDK allows you to define infrastructure as code using C#.
Step 1: Install AWS CDK
npm install -g aws-cdk
Step 2: Define Infrastructure in C#
var lambdaFunction = new Function(this, "ProductLambda",
new FunctionProps
{
Runtime = Runtime.DOTNET_8,
Code = Code.FromAsset("ServerlessProductAPI/bin/Release/net8.0/publish"),
Handler = "ServerlessProductAPI::Function::CreateProduct"
});
var api = new RestApi(this, "ProductAPI",
new RestApiProps { RestApiName = "Product Service" });
var productsResource = api.Root.AddResource("products");
productsResource.AddMethod("POST", new LambdaIntegration(lambdaFunction));
Step 3: Deploy
cdk deploy
✅ This fully automates deployment of Lambda, API Gateway, and DynamoDB.
8. Securing the Serverless API
A. Enforcing Authentication (Cognito + JWT)
aws cognito-idp create-user-pool --pool-name MyUserPool
Modify API Gateway to require authentication:
aws apigateway update-method --rest-api-id <api-id> --resource-id <resource-id> --http-method POST --patch-operations '[{"op": "replace", "path": "/authorizationType", "value": "COGNITO_USER_POOLS"}]'
B. Implementing Rate Limiting
aws apigateway create-usage-plan --name "BasicPlan" --throttle rateLimit=10,burstLimit=5
This prevents API abuse by limiting requests.
9. Monitoring with AWS CloudWatch
Enable CloudWatch logging for API Gateway:
aws apigateway update-stage --rest-api-id <api-id> --stage-name prod --patch-operations '[{"op": "replace", "path": "/*/*/logging/loglevel", "value": "INFO"}]'
Now, every request logs execution details for debugging.
Conclusion
In this article, we built a serverless .NET 8 API using:
✅ AWS Lambda for auto-scaling execution.
✅ API Gateway for exposing APIs.
✅ DynamoDB for persistence.
✅ AWS CDK for infrastructure automation.
✅ Cognito & Rate Limiting for security.
Next, we’ll explore integrating AI-powered APIs using AWS Bedrock and .NET 8! 🚀