OpenFaaS PowerShell HTTP function template

This template for building Powershell based functions on OpenFaaS, Docker, Knative and Cloud Run.

With this template you can create a new function and deploy it to a platform like OpenFaaS for:

scale-to-zero
horizontal scale-out
metrics & logs
automated health-checks
sane Kubernetes defaults like running as a non-root user

Status of the template

This template is experimental and I would like your feedback through GitHub issues or OpenFaaS Slack.

Get started

You can create or scaffold a new function using the OpenFaaS CLI.

# USERNAME is your Docker Hub account or private Docker registry
$ export USERNAME=alexellisuk

$ faas template pull https://github.com/openfaas-incubator/powershell-http-template
$ faas new --lang powershell-http <fn-name> --prefix="${USERNAME}"

Once you've written your code you can run faas-cli build to create a local Docker image, then faas-cli push to transfer it to your registry.

You can now deploy it to OpenFaaS, Knative, Google Cloud Run or even use docker run.

Example usage

Minimal string based example

function Handler {
  Param(
  [Parameter(Mandatory=$true)]
  [FunctionContext]$fnContext,
  [Parameter(Mandatory=$true)]
  [FunctionResponse]$fnResponse
  )

  $output = "Hello! Your input was: " + $fnContext.Body

  $fnResponse.Body = $output
  
}

Minimal JSON based example

function Handler {
  Param(
  [Parameter(Mandatory=$true)]
  [FunctionContext]$fnContext,
  [Parameter(Mandatory=$true)]
  [FunctionResponse]$fnResponse
  )

  $json = $fnContext.Body | Out-String | ConvertFrom-Json 

  $key1 = $json.key1
  $key2 = $json.key2

  $output = @{
      "Your JSON input was" = @{
          key1=$key1;
          key2=$key2;
      }
  } | ConvertTo-Json -Compress

  $fnResponse.Body = $output
  
}

Example usage with WinRM based remote PowerShell module, environment variables and secrets.

function Handler {
  Param(
  [Parameter(Mandatory=$true)]
  [FunctionContext]$fnContext,
  [Parameter(Mandatory=$true)]
  [FunctionResponse]$fnResponse
  )

  $username = $env:USERNAME
  $password = Get-Content "/var/openfaas/secrets/password" | ConvertTo-SecureString -AsPlainText -Force
  $cred = New-Object System.Management.Automation.PSCredential -ArgumentList ($username, $password)

  $sessionoptions = New-PSSessionOption -SkipCACheck -SkipCNCheck
  $output = Invoke-Command -ComputerName <winrm-server> -Authentication Negotiate -SessionOption $sessionoptions -Credential $cred -ScriptBlock {
    Import-module ActiveDirectory
    Get-Domain
  }

  $fnResponse.Body = $output

}

MnrGreg / powershell-http-template