.NET 6 Lambdas on ARM64 - Part 1, Functions

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AWS Lambda allows you to run your code using x86_64 and ARM64 processors. The default Lambda templates use x86_64, but it is very easy to change these to use ARM64.

I have a few other posts on running .NET 6 on AWS Lambda.

Getting the tools

Install the latest tooling, this lets you deploy and run Lambdas.

dotnet tool install -g Amazon.Lambda.Tools

Install the latest templates to get .NET 6 support.

dotnet new --install Amazon.Lambda.Templates

A little background

To see a list of the available Lambda templates run -

dotnet new lambda --list

You will see a list like this -

Template Name                             Short Name                                    Language  Tags
----------------------------------------  --------------------------------------------  --------  ---------------------
Empty Top-level Function                  lambda.EmptyTopLevelFunction                  [C#]      AWS/Lambda/Serverless
Lambda ASP.NET Core Minimal API           serverless.AspNetCoreMinimalAPI               [C#]      AWS/Lambda/Serverless
Lambda ASP.NET Core Web Application w...  serverless.AspNetCoreWebApp                   [C#]      AWS/Lambda/Serverless
Lambda Custom Runtime Function (.NET 6)   lambda.CustomRuntimeFunction                  [C#],F#   AWS/Lambda/Function
Lambda Detect Image Labels                lambda.DetectImageLabels                      [C#],F#   AWS/Lambda/Function
Lambda Empty Function                     lambda.EmptyFunction                          [C#],F#   AWS/Lambda/Function
Lambda Empty Function (.NET 6 Contain...  lambda.image.EmptyFunction                    [C#],F#   AWS/Lambda/Function
Lambda Empty Serverless                   serverless.EmptyServerless                    [C#],F#   AWS/Lambda/Serverless
Lambda Empty Serverless (.NET 6 Conta...  serverless.image.EmptyServerless              [C#],F#   AWS/Lambda/Serverless
Lambda Giraffe Web App                    serverless.Giraffe                            F#        AWS/Lambda/Serverless
Lambda Simple Application Load Balanc...  lambda.SimpleApplicationLoadBalancerFunction  [C#]      AWS/Lambda/Function
Lambda Simple DynamoDB Function           lambda.DynamoDB                               [C#],F#   AWS/Lambda/Function
Lambda Simple Kinesis Firehose Function   lambda.KinesisFirehose                        [C#]      AWS/Lambda/Function
Lambda Simple Kinesis Function            lambda.Kinesis                                [C#],F#   AWS/Lambda/Function
Lambda Simple S3 Function                 lambda.S3                                     [C#],F#   AWS/Lambda/Function
Lambda Simple SNS Function                lambda.SNS                                    [C#]      AWS/Lambda/Function
Lambda Simple SQS Function                lambda.SQS                                    [C#]      AWS/Lambda/Function
Lex Book Trip Sample                      lambda.LexBookTripSample                      [C#]      AWS/Lambda/Function
Order Flowers Chatbot Tutorial            lambda.OrderFlowersChatbot                    [C#]      AWS/Lambda/Function

Note how some of the templates start with lambda and some with serverless. A single configuration change is needed to deploy to ARM64, but the change depends on the template you are using.

lambda vs serverless templates

Applications built from lambda.* templates are invoked by sending JSON requests to them, directly, from other applications, or from other services.

Applications built from serverless.* templates are invoked by sending HTTP requests to them via an API Gateway.

Moving to ARM64

If you are using the lambda. templates, a change is needed to aws-lambda-tools-defaults.json, covered in this post.

If you are using the serverless. templates, a change is needed to the serverless.templates file and will be covered in the next post.

Create the application with the lambda.* template

Create a simple Lambda function with the lambda.EmptyFunction template -

dotnet new lambda.EmptyFunction --name LambdaEmptyFunctionArm64

Edit the deployment configuration

Navigate to the LambdaEmptyFunctionArm64\src\LambdaEmptyFunctionArm64 directory.

Open the aws-lambda-tools-defaults.json file and add this -

"function-architecture": "arm64",

Your file should look something like -

  "Information": [
  "profile": "",
  "region": "",
  "configuration": "Release",
  "function-runtime": "dotnet6",
  "function-architecture": "arm64",
  "function-memory-size": 256,
  "function-timeout": 30,
  "function-handler": "LambdaEmptyFunctionArm64::LambdaEmptyFunctionArm64.Function::FunctionHandler"

Update the FunctionHandler method

Open Function.cs and replace the FunctionHandler(..) method with this -

public string FunctionHandler(string input, ILambdaContext context)
    var architecture = System.Runtime.InteropServices.RuntimeInformation.ProcessArchitecture;
    var dotnetVersion = Environment.Version.ToString();
    return $"Architecture: {architecture}, .NET Version: {dotnetVersion} -- {input?.ToUpper()}";

Try building the code before moving on to deploying the application.


Deploy using -

dotnet lambda deploy-function --functionname LambdaEmptyFunctionArm64

You’ll be asked which IAM role you want to use, the last number on the list will be for *** Create new IAM Role ***, pick that. Then enter a name for the role, something like LambdaNet6_role will do. Finally, you’ll be asked what permissions to grant, select AWSLambdaRole (it is number 9 on my list). It will then take a moment or two to create the role.

That’s it, you now have a .NET 6 Lambda function running on ARM64 processors.

Running the Lambda

You can test the function with the following -

dotnet lambda invoke-function LambdaEmptyFunctionArm64 --payload "hello arm64"

You should get a response that includes this -

"Architecture: Arm64, .NET Version: 6.0.1 -- HELLO ARM64"

Download full source code.

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