Extensions for aws-lambda-dotnet

aws-lambda-dotnet provides a LambdaServer to integrate with APIGateway requests.

This project introduces couple of extension points to connect other types of integrations (SQS, CustomAuthorizer etc.) to .NET application host

It provides:

• .NET-idiomatic experience to create lambda function handlers without worrying about host services (configuration, DI, logging) similar to the existing APIGateway integration
• local lambda invocation with an HTTP endpoint to be used with common tools (Postman, curl)
• sam local invocation (TODO)

Usage

1. Create a ASP.NET Core project as you would normally (e.g. dotnet new webapi)

2. Implement a function handler by implementing ILambdaFunctionHandler<TRequest,TResponse>:HandleAsync() method. TRequest is the type of event received from Lambda (e.g. APIGatewayCustomAuthorizerRequest) and TResponse is the type of response to be returned (e.g. APIGatewayCustomAuthorizerResponse)

    public class CustomAuthorizerHandler : ILambdaFunctionHandler<APIGatewayCustomAuthorizerRequest, APIGatewayCustomAuthorizerResponse>
    {
        public Task<APIGatewayCustomAuthorizerResponse> HandleAsync(APIGatewayCustomAuthorizerRequest request)
        { 
            ...
        }
    }

3. To configure the Host, extend AbstractDotNetCoreFunction<TRequest, TResponse> and override the Init method and register the handler

    public class APIGatewayCustomAuthorizerFunction : AbstractDotNetCoreFunction<APIGatewayCustomAuthorizerRequest, APIGatewayCustomAuthorizerResponse>
    {
        protected override void Init(IHostBuilder builder)
        {
            builder
                .UseLambda<APIGatewayCustomAuthorizerRequest, APIGatewayCustomAuthorizerResponse, CustomAuthorizerHandler>();
        }
    }

4. To be able to run the application locally, create a GenericHost with a local lambda server

        public static async Task Main(string[] args)
        {
            await CreateHostBuilder(args).Build().RunAsync();
        }

        public static IHostBuilder CreateHostBuilder(string[] args)
        {
            return Host.CreateDefaultBuilder(args)
                .UseLambdaLocal<APIGatewayCustomAuthorizerRequest, APIGatewayCustomAuthorizerResponse,
                    CustomAuthorizerHandler>();
        }

This will allow to test events with something like following (e.g. simulate APIGatewayCustomAuthorizerRequest)

curl -X POST http://localhost:5000/ -d \
'{
    "type": "aaa",
    "authorizationToken": "bbb",
    "methodArn": "ccc",
    "path": "ddd",
    "httpMethod": "POST",
    "headers": null,
    "queryStringParameters": null,
    "pathParameters": null,
    "stageVariables": null
}'

5. Lambda handler needs to be configured as

<dll>::<Namespace>.<ClassExtendingGenericProxyFunction>::FunctionHandlerAsync

e.g. APIGatewayCustomAuthorizer::APIGatewayCustomAuthorizer.APIGatewayCustomAuthorizerFunction::FunctionHandlerAsync

Example

1. To build the sample, run ./deploy/Build.ps1
2. To deploy, run ./deploy/Deploy.ps1 <artificatsBucket> where <artificatsBucket> is a bucket to store the Lambda code and artifacts.