Migrating to AWS: Using the AWS SDK for .NET in Enterprise Projects

Hands-On Examples: S3, DynamoDB, and Lambda with the AWS SDK for .NET

This guide shows concise, practical examples for using AWS services from a .NET application with the AWS SDK for .NET (AWSSDK). It assumes .NET 6+ and the AWSSDK NuGet packages. Each example includes setup, code snippets, and key tips.

Prerequisites

• .NET 6+ SDK installed.
• AWS credentials configured (e.g., ~/.aws/credentials, environment variables, or AWS IAM role).
• Install packages (examples):

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dotnet add package AWSSDK.S3 dotnet add package AWSSDK.DynamoDBv2 dotnet add package AWSSDK.Lambda 

1) Amazon S3 — Upload and Download a File

• Use AmazonS3Client from Amazon.S3.
• Upload:

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using Amazon.S3;
using Amazon.S3.Transfer;

var s3Client = new AmazonS3Client(region: Amazon.RegionEndpoint.USEast1);
var transferUtility = new TransferUtility(s3Client);
await transferUtility.UploadAsync(“local-file.txt”, “my-bucket”, “folder/local-file.txt”);

• Download:

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await transferUtility.DownloadAsync(“downloaded.txt”, “my-bucket”, “folder/local-file.txt”);

• Tips: use TransferUtility for large files, enable server-side encryption by setting PutObjectRequest.ServerSideEncryption, set ACLs carefully, and use presigned URLs for temporary access.

2) Amazon DynamoDB — Basic CRUD

• Use AmazonDynamoDBClient and DynamoDBContext (Object Persistence Model).
• Define a model:

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using Amazon.DynamoDBv2.DataModel;

[DynamoDBTable(“Users”)]
public class User {
[DynamoDBHashKey] public string UserId { get; set; }
  [DynamoDBProperty] public string Name { get; set; }
  [DynamoDBProperty] public int Age { get; set; }
}

• Save (Create/Update):

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var client = new AmazonDynamoDBClient();
var context = new DynamoDBContext(client);
await context.SaveAsync(new User { UserId = “u123”, Name = “Alex”, Age = 30 });

• Read:

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var user = await context.LoadAsync<User>(“u123”);

• Delete:

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await context.DeleteAsync<User>(“u123”);

• Query/Scan: prefer Query with a proper key design for performance; use AsyncSearch for paginated results.
• Tips: design partition/sort keys for access patterns, use batch operations for throughput, enable adaptive capacity and auto-scaling for production.

3) AWS Lambda — Invoke Function and Local Testing

• Use AmazonLambdaClient to invoke functions.
• Invoke synchronous:

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using Amazon.Lambda;
using Amazon.Lambda.Model;

var lambda = new AmazonLambdaClient();
var payload = ”{“name”:“Alex”}”;
var response = await lambda.InvokeAsync(new InvokeRequest {
  FunctionName = “MyFunction”,
  Payload = payload,
  InvocationType = InvocationType.RequestResponse });
using var sr = new StreamReader(response.Payload);
var result = await sr.ReadToEndAsync();

• Invoke asynchronously by setting InvocationType.Event.
• Local testing: use AWS SAM CLI or .NET Lambda Test Tool to run and debug functions locally.
• Deployment: use Amazon.Lambda.Tools (dotnet lambda deploy-function) or CI pipelines (SAM/CDK).
• Tips: keep Lambda handlers small, use dependency injection with Amazon.Lambda.AspNetCoreServer for web apps, and set proper memory/timeout.

4) Cross-cutting concerns & best practices

• Credential handling: prefer IAM roles for EC2/ECS/Lambda; avoid hardcoding keys.
• Async/await: use asynchronous APIs to avoid thread blocking.
• Retry & backoff: rely on SDK default retry or configure exponential backoff for transient errors.
• Logging & monitoring: integrate CloudWatch, X-Ray tracing, and structured logs.
• Security: least-privilege IAM policies, encrypt sensitive data, rotate keys if any.
• Performance: reuse client instances (they are thread-safe), tune HTTP connection settings, and use paginated APIs efficiently.

5) Quick sample project layout

• Console app or ASP.NET Core service
  • Services/S3Service.cs
  • Services/DynamoDbService.cs
  • Services/LambdaService.cs
  • Models/
  • Program.cs (DI registration)
• Include integration tests using LocalStack or AWS SAM for safe testing.