« Lambda » : différence entre les versions

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     public void Handle(SQSEvent sqsEvent, ILambdaContext context) { }
     public void Handle(SQSEvent sqsEvent, ILambdaContext context) { }
}
}
</kode>
= [https://docs.aws.amazon.com/lambda/latest/dg/csharp-dev-env.html Setting up your .NET development environment] =
<kode lang='ps'>
# install the VS project template
dotnet new install Amazon.Lambda.Templates
# install the command line tools
dotnet tool install -g Amazon.Lambda.Tools
</kode>
</kode>


Version du 15 avril 2024 à 13:55

Links

Description

Serverless service / Function as a service allowing to run code without having to worry about underlying hardware and OS.
Event driven: the lambda is triggered by an event.
Pay only for what you use: per request and based on the duration of the code execution.

Use cases

  • Data transformation (Kinesis Data Stream as input)
  • File processing (when uploaded to S3 bucket)
  • Website backend microservice
  • Scheduled tasks

Bad use cases

  • Long running processes (timeout after 15mn)
  • Constant workload (no scalability and high cost)
  • Large code base (needed to be loaded at startup)
  • State management (lambda are stateless)

Anti-patterns

  • Monolithic function
    • increase package size
    • hard to enforce least privilege permissions
    • hard to upgrade, maintain and test
  • Recursion
    • endless loop
  • Orchestration
    • avoid complex workflow logic
    • ties lambda with other systems
    • instead consider AWS Step Functions or EventBridge
  • Chaining (synchronously invoke another lambda)
    • instead use EventBridge or QueueService
  • Waiting (synchronously call services or databases)
    • instead use asynchronous calls

Runtime

  • OS
  • Libraries
  • Programming language (.NET, Node.js, Python, Go, Ruby, Java)

Environnement variables

DOTNET_STARTUP_HOOKS ex: path to an assembly to inject logging

Wrapper scripts

Execute the wrapper on top of the runtime and the lambda function.

  • run shell commands and binaries

Use AWS_LAMBDA_EXEC_WRAPPER to point to your wrapper script.

Custom runtime

Provide your custom runtime.

  • unsupported programming language

Handler (entry point)

Method responsible for processing input events.

synchronous execution result returned to the calling app
asynchronous execution result sent to the configured destination otherwise lost

Executing lambda

Function.cs 
var handler = (string input, ILambdaContext context) =>
{
    return input.ToUpper();
};

await LambdaBootstrapBuilder.Create(handler, new DefaultLambdaJsonSerializer()).Build().RunAsync();

Library lambda

Cs.svg 
[assembly: LambdaSerializer(typeof(Amazon.Lambda.Serialization.SystemTextJson.CamelCaseLambdaJsonSerializer))]
namespace MyNamespace;

public class Function
{
    public APIGatewayProxyResponse Handle(APIGatewayProxyRequest request, ILambdaContext context)
    {
        var id = request.PathParameters["id"];

        var function = $"{context.FunctionName} {context.FunctionVersion}";
        var cognitoIdentity = context.Identity;
        context.Logger.LogLine("Message");
        
        return new APIGatewayProxyResponse 
        {
            StatusCode = (int)HttpStatusCode.OK,
            Body = JsonSerializer.Serialize(id)
        };
    }

    public void Handle(SQSEvent sqsEvent, ILambdaContext context) { }
}

Setting up your .NET development environment

Ps.svg 
# install the VS project template
dotnet new install Amazon.Lambda.Templates

# install the command line tools
dotnet tool install -g Amazon.Lambda.Tools

.NET 8

scenario description
Native AOT
Custom Runtime Function to use .NET 8
Container Image lambda function package as a container image

Debug locally

On VS, if the extension AWS Toolkit is installed you have the AWS .NET Mock Lambda Test Tool available.
A debug configuration is created for you lambda.

Properties\launchSettings.json 
{
  "profiles": {
    "Mock Lambda Test Tool": {
      "commandName": "Executable",
      "commandLineArgs": "--port 5050",
      "executablePath": "<home-directory>\\.dotnet\\tools\\dotnet-lambda-test-tool-6.0.exe",
      "workingDirectory": ".\\bin\\Debug\\net6.0"
    }
  }
}

Deployment

Lambda function handler in C#

For class libraries: ASSEMBLY::TYPE::METHOD

Call a lambda from code

Cs.svg 
var jsonSerializerOptions = new JsonSerializerOptions
{
    PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
    Converters = { new JsonStringEnumConverter() }
};

var amazonLambdaClient = new AmazonLambdaClient();

var request = new InvokeRequest
{
    FunctionName = functionName,
    Payload = JsonSerializer.Serialize(myObject, jsonSerializerOptions),
    LogType = LogType.Tail
};
var response = await this.amazonLambdaClient.InvokeAsync(request);

if(response.HttpStatusCode == System.Net.HttpStatusCode.OK)
{
    var payload = Encoding.ASCII.GetString(response.Payload.ToArray()); // to debug only
    var result = JsonSerializer.Deserialize<AwsJobResult<LambdaJob>>(response.Payload, jsonSerializerOptions);
}
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