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AWS Lambda

Pode has support for being used within AWS Lambda PowerShell Functions, helping you with routing and responses, but also leveraging middleware, authentication, and other features of Pode.

Overview

When you use Pode in a serverless environment, the server logic is run once, and the route logic immediately parsed; any response is returned, and the server disposed. Unlike the normal web-server logic of Pode, when in serverless the server logic doesn't continually loop.

Usage

Module

Your PowerShell Function script will need to have the Pode module imported, so it can be used. To do this, the following line is required at the top of your script (as well as the normal AWS module):

#Requires -Modules @{ModuleName='AWSPowerShell.NetCore';ModuleVersion='3.3.509.0'}
#Requires -Modules @{ModuleName='Pode';ModuleVersion='<version>'}

Template

One Function can accept many routes if you setup the template. Your SAM/serverless YAML template could look as follows:

AWSTemplateFormatVersion : '2010-09-09'
Transform: 'AWS::Serverless-2016-10-31'
Resources:
  ExampleFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: 'Example::Example.Bootstrap::ExecuteFunction'
      Runtime: dotnetcore2.1
      CodeUri: Example.zip
      Timeout: 60
      MemorySize: 256
      Events:
        Example:
          Type: Api
          Properties:
            Path: /{proxy+}
            Method: get

Here, the /{proxy+} will enable one Function for all routes - which can be controlled via Pode within your Function.

The Server

With the above being done, your Pode server can be created as follows. The $LambdaInput is a parameter supplied to your Function by AWS:

Start-PodeServer -Request $LambdaInput -ServerlessType AwsLambda {
    # logic
}

Routing

Let's say for your Function you have it setup for multiple routes, and you've enabled the GET method.

The following script would be a simple example of using Pode to aid with routing in this Function:

#Requires -Modules @{ModuleName='AWSPowerShell.NetCore';ModuleVersion='3.3.509.0'}
#Requires -Modules @{ModuleName='Pode';ModuleVersion='<version>'}

Start-PodeServer -Request $LambdaInput -ServerlessType AwsLambda {
    # get some user data
    Add-PodeRoute -Method Get -Path '/users' -ScriptBlock {
        Write-PodeJsonResponse -Value @{ 'Users' = @() }
    }

    # get some messages data
    Add-PodeRoute -Method Get -Path '/message' -ScriptBlock {
        Write-PodeJsonResponse -Value @{ 'UserId' = 123; 'Messages' = @() }
    }
}

Websites

You can render websites using Pode as well. To do this in Lambda Functions you'll need to upload your website files to some S3 bucket. In here you can place your normal /views, /public and /errors directories - as well as your server.psd1 file.

Then within your Function script, you need to read in the data from your S3 bucket to some path your Function can access. Once read in, you need to then reference this directory as the root path for your server:

#Requires -Modules @{ModuleName='AWSPowerShell.NetCore';ModuleVersion='3.3.509.0'}
#Requires -Modules @{ModuleName='Pode';ModuleVersion='<version>'}

Read-S3Object -BucketName '<bucket-name>' -KeyPrefix '<dir-name>' -Folder '/tmp/www' | Out-Null

Start-PodeServer -Request $LambdaInput -ServerlessType AwsLambda -RootPath '/tmp/www' {
    # set your engine renderer
    Set-PodeViewEngine -Type Pode

    # get route for your 'index.pode' view
    Add-PodeRoute -Method Get -Path '/home' -ScriptBlock {
        Write-PodeViewResponse -Path 'index'
    }
}

Static Content

Unlike Azure Functions, static content in AWS Functions can be served up in the normal way - assuming your function can recieve multiple routes.

For example, if you have a CSS stylesheet at /tmp/www/styles/main.css.pode, then your index.pode view would get this as such:

<html>
    <head>
        <title>Example</title>
        <link rel="stylesheet" type="text/css" href="/styles/main.css.pode">
    </head>
    <body>
        <img src="/SomeImage.jpg" />
    </body>
</html>

Responses

Pode will handle returning an appropriate response object for you, dealing with the Status Code, Body, Headers, etc. There's no need to return the normal hashtable from your Function.

Unsupported Features

Unfortunately not all the features of Pode can be used within a serverless environment. Below is a list of features in Pode that cannot be used when running in a serverless context:

  • Access Middleware
  • Limit Middleware
  • Opening your server as a GUI
  • TCP/Service Handler logic
  • Listening on endpoints (as AWS Lambda does this for us)
  • Schedules
  • Timers
  • File Monitoring
  • Server Restarting