Azure VM scale set environment variables for Terraform input

scale-set-agent-terraform-input-vars.yaml

- pwsh: |
    # 1. Use pipeline agent VNet as network to peer from
    $env:TF_VAR_peer_network_id ??= $env:GEEKZTER_AGENT_VIRTUAL_NETWORK_ID

    # 2. Set random CIDR (to reduce the risk of clashing VNet peerings with agent VNet)
    $env:TF_VAR_address_space ??= "$([IPAddress]::Parse(`
        [String] (`
          167772160 + (`
            65536*(`
              Get-Random -Minimum 0 -Maximum 255 -SetSeed $(Build.BuildId)`
            )`
          )`
        )`
      ) | Select-Object -ExpandProperty IPAddressToString)/16"
                                    
    # Set unique resource suffix
    $env:TF_VAR_resource_suffix ??= "$(Build.BuildId)"
    
    # Convert uppercased Terraform environment variables to Terraform arguments
    foreach ($tfvar in $(Get-ChildItem -Path Env: -Recurse -Include TF_VAR_*)) {
      $terraformVariableName = $tfvar.Name.Substring(7).ToLowerInvariant()
      $terraformVariableValue = $tfVar.Value
      $varArgs += " -var ${terraformVariableName}=${terraformVariableValue}"
    } 
    Write-Host "##vso[task.setvariable variable=variableOption;isOutput=true]$varArgs"
  name: terraformVariables
  displayName: 'Prepare Terraform variables'
  workingDirectory: '$(terraformDirectory)'