Validate Azure ARM template

ValidateAzureTemplate.ps1

function Format-ValidationOutput {
    Param (
        [Parameter(ValueFromPipeline=$true)] $ValidationOutput,
        [int] $Depth = 0
    )

    return @($ValidationOutput | Where-Object { $_ -ne $null } | ForEach-Object { @('  ' * $Depth + ': ' + $_.Message) + @(Format-ValidationOutput @($_.Details) ($Depth + 1)) })
}

# Template

$template = $DeployAzureResourceGroupStep.Azure.ResourceGroupTemplate
Write-Verbose $template

$templateFile = New-TemporaryFile
Set-Content -Value $template -Path $templateFile

# Parameters (convert JSON to Hashtable)
$templateParameters = @{}
$tmp = $DeployAzureResourceGroupStep.Azure.ResourceGroupTemplateParameters | ConvertFrom-Json
$tmp.PSObject.Properties | ForEach-Object { $templateParameters[$_.Name] = $_.Value.value }

Write-Host "Template: $templateFile"
$templateParameters | Format-Table -AutoSize
Write-Host "Verifying ARM Template..." -NoNewline
  
$errorMessages = Test-AzureRmResourceGroupDeployment -ResourceGroupName $ResourceGroupName -TemplateFile $templateFile -TemplateParameterObject $templateParameters
$errorMessages = $errorMessages | Format-ValidationOutput

if ($errorMessages) {
  Write-Host " FAILED" -ForegroundColor Red
  Throw "$name Azure Deployment Template is invalid with the following errors: $errorMessages"
}

Write-Host " VALID" -ForegroundColor Green