Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Tutorial: Build and Test a Serverless Application with Amazon Lambda

You can build a serverless Lambda application by using an Amazon Toolkit for Visual Studio template. The Lambda project templates include one for an Amazon Serverless Application, which is the Amazon Toolkit for Visual Studio implementation of the Amazon Serverless Application Model (Amazon SAM). Using this project type you can develop a collection of Amazon Lambda functions and deploy them with any necessary Amazon resources as a whole application, using Amazon CloudFormation to orchestrate the deployment.

For prerequisites and information about setting up the Amazon Toolkit for Visual Studio, see Using the Amazon Lambda Templates in the Amazon Toolkit for Visual Studio.

Create a New Amazon Serverless Application Project

Amazon Serverless Application projects create Lambda functions with a serverless Amazon CloudFormation template. Amazon CloudFormation templates enable you to define additional resources such as databases, add IAM roles, and deploy multiple functions at one time. This differs from Amazon Lambda projects, which focus on developing and deploying a single Lambda function.

The following procedure describes how to create a new Amazon Serverless Application Project.

Reviewing the Serverless Application files

The following sections provide a detailed look at three Serverless Application files created for your project:

1. serverless.template

A serverless.template file is an Amazon CloudFormation template for declaring your Serverless functions and other Amazon resources. The file included with this project contains a declaration for a single Lambda function that will be exposed through the Amazon API Gateway as an HTTP *Get* operation. You can edit this template to customize the existing function or add more functions and other resources that are required by your application.

The following is an example of a serverless.template file:

{
  "AWSTemplateFormatVersion": "2010-09-09",
  "Transform": "AWS::Serverless-2016-10-31",
  "Description": "An AWS Serverless Application.",
  "Resources": {
    "Get": {
      "Type": "AWS::Serverless::Function",
      "Properties": {
         "Architectures": [
            "x86_64"
            ],
         "Handler": "ServerlessPowertools::ServerlessPowertools.Functions::Get",
         "Runtime": "dotnet8",
         "CodeUri": "",
         "MemorySize": 512,
         "Timeout": 30,
         "Role": null,
         "Policies": [
            "AWSLambdaBasicExecutionRole"
            ],
         "Environment": {
            "Variables": {
               "POWERTOOLS_SERVICE_NAME": "ServerlessGreeting",
               "POWERTOOLS_LOG_LEVEL": "Info",
               "POWERTOOLS_LOGGER_CASE": "PascalCase",
               "POWERTOOLS_TRACER_CAPTURE_RESPONSE": true,
               "POWERTOOLS_TRACER_CAPTURE_ERROR": true,
               "POWERTOOLS_METRICS_NAMESPACE": "ServerlessGreeting"
               }
            },
         "Events": {
            "RootGet": {
               "Type": "Api",
               "Properties": {
                  "Path": "/",
                  "Method": "GET"
                  }
               }
            }
         }
      }
   },
  "Outputs": {
    "ApiURL": {
      "Description": "API endpoint URL for Prod environment",
      "Value": {
        "Fn::Sub": "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/"
      }
    }
  }
}

Notice that many of the ...AWS:: Serverless::Function... declaration fields are similar to the fields of a Lambda project deployment. Powertools Logging, Metrics and Tracing are configured through the following environment variables:

For definitions and additional details about the environment variables, see the Powertools for Amazon Lambda references website.

2. Functions.cs

Functions.cs is a class file containing a C# method that's mapped to a single function declared in the template file. The Lambda function responds to HTTP Get methods from API Gateway. The following is an example of the Functions.cs file:

public class Functions
{
    [Logging(LogEvent = true, CorrelationIdPath = CorrelationIdPaths.ApiGatewayRest)]
    [Metrics(CaptureColdStart = true)]
    [Tracing(CaptureMode = TracingCaptureMode.ResponseAndError)]
    public APIGatewayProxyResponse Get(APIGatewayProxyRequest request, ILambdaContext context)
    {
        Logger.LogInformation("Get Request");

        var greeting = GetGreeting();

        var response = new APIGatewayProxyResponse
        {
            StatusCode = (int)HttpStatusCode.OK,
            Body = greeting,
            Headers = new Dictionary (string, string) { { "Content-Type", "text/plain" } }
        };

        return response;
    }

    [Tracing(SegmentName = "GetGreeting Method")]
    private static string GetGreeting()
    {
        Metrics.AddMetric("GetGreeting_Invocations", 1, MetricUnit.Count);

        return "Hello Powertools for AWS Lambda (.NET)";
    }
}

3. aws-lambda-tools-defaults.json

aws-lambda-tools-defaults.json provides the default values for the Amazon deployment wizard inside Visual Studio and the Amazon Lambda commands added to the .NET Core CLI. The following is an example of the aws-lambda-tools-defaults.json file included with this project:

{
  "profile": "Default",
  "region": "us-east-1",
  "configuration": "Release",
  "s3-prefix": "ServerlessPowertools/",
  "template": "serverless.template",
  "template-parameters": ""
}

Deploying the Serverless Application

To deploy your serverless application complete the following steps

Test the Serverless Application

When the stack creation is complete, you can view your application using the Amazon Serverless URL. If you've completed this tutorial without adding any additional functions or parameters, accessing your Amazon serverless URL displays the following phrase in your web browser: Hello Powertools for AWS Lambda (.NET).