The AWS Lambda Tools for Powershell

The AWS Lambda Tools for Powershell allows PowerShell developers to publish PowerShell scripts with their dependent modules and have the scripts be invoked by Lambda.

Setting up a development environment

Before we get started developing PowerShell based Lambda functions, let's set up our development environment.

First, we need to set up the correct version of PowerShell. AWS Lambda support for PowerShell is based on the cross-platform PowerShell release. This means you can develop your Lambda functions for PowerShell on Windows, Linux, or Mac. If you don't have this version of PowerShell installed, you can find instructions here.

If you are using Visual Studio Code on Windows as your IDE, you need to ensure it's configured for PowerShell Core. To learn how to configure Visual Studio Code for PowerShell Core, see the following: https://learn.microsoft.com/en-us/powershell/scripting/dev-cross-plat/vscode/using-vscode?view=powershell-7.4

Next, we need to install the .NET 8 SDK. Because PowerShell Core is built on top of .NET Core, the Lambda support for PowerShell uses the same .NET 8 Lambda runtime for both .NET Core and PowerShell based Lambda functions. The .NET 8 SDK is used by the new PowerShell publishing cmdlets for Lambda to create the Lambda deployment package. You can find the .NET 8 SDK here. Be sure to install the SDK, not the runtime installation.

The last component we need for the development environment is the new AWSLambdaPSCore module that you can install from the PowerShell Gallery. The following is an example of installing the module from a PowerShell Core shell.

Install-Module AWSLambdaPSCore -Scope CurrentUser

This new module has the following new cmdlets to help you author and publish PowerShell based Lambda functions.

Cmdlet name	Description
Get-AWSPowerShellLambdaTemplate	Returns a list of getting started templates.
New-AWSPowerShellLambda	Used to create an initial PowerShell script that is based on a template.
Publish-AWSPowerShellLambda	Publishes a given PowerShell script to Lambda.
New-AWSPowerShellLambdaPackage	Creates the Lambda deployment package that can be used in a CI/CD system for deployment.

Troubleshooting

Enabling Debug output

In PowerShell, Write-Debug CmdLet could be used to write debug message to the console. However, by default, debug messages are not displayed in the console, but you can display them by using the Debug parameter or the $DebugPreference variable.

The default value of DebugPreference variable is SilentlyContinue, which means the debug message isn't displayed and execution continues without interruption. The -Debug parameter could be used to override the $DebugPreference value.

Enabling output of Write-Debug to CloudWatch logs is a 2 step process:

• In PowerShell Lambda script,

  • Either need to set $DebugPreference = "Continue" at the beginning of script. Thereafter use Write-Debug to output debug messages ; OR
  • Include -Debug parameter while executing Write-Debug (e.g. Write-Debug "Testing Lambda PowerShell Write-Debug" -Debug).

• At Lambda function level, set the value of AWS_LAMBDA_HANDLER_LOG_LEVEL environment variable with value DEBUG. This would enable debug logs at Lambda level. This environment variable could be set:

  • Either manually in Lambda function configuration in AWS console; OR
  • While executing CmdLet Publish-AWSPowerShellLambda, passing parameter -EnvironmentVariable @{'AWS_LAMBDA_HANDLER_LOG_LEVEL'='DEBUG'}.

  The value of the AWS_LAMBDA_HANDLER_LOG_LEVEL environment variable is set to the values of the LogLevel enum.

The role assigned to Lambda function should have permissions to write to CloudWatch logs.

Learning Resources

Lambda Developer Guide

• Programming Model for Authoring Lambda Functions in PowerShell
• Creating a Deployment Package (PowerShell)

AWS Blog Posts

• Announcing Lambda Support for PowerShell Core
• Deploying PowerShell-based Lambda with AWS CloudFormation
• Creating a PowerShell REST API

AWS Recorded Talks

• Unleash your PowerShell with AWS Lambda and Serverless Computing - PowerShell and DevOps Global Summit 2019 by Andrew Pearce
  • Introduces PowerShell language support in AWS Lambda, introduces event driven design patterns and demonstrates a PowerShell Serverless application using Amazon Simple Notification Service (SNS), Amazon Simple Queue Service (SQS) and Amazon API Gateway.