azure function return event grid validation event

event-grid-function-test.ps1

# POST method: $req
$requestBody = Get-Content $req -Raw | ConvertFrom-Json

## validate event grid as described in https://docs.microsoft.com/en-us/azure/event-grid/security-authentication
# check event type and return a Json object with the correct validation response
if ($requestBody.eventType -eq "Microsoft.EventGrid.SubscriptionValidationEvent") {
    $code = $requestBody.data.validationCode
    $content = @{ validationResponse = $code }
    $message = convertto-json -compress -InputObject ([ordered]@{
        body = $content
        statusCode = 200
    })

    Out-File -Encoding Ascii -FilePath $res -inputObject $($message)
    write-output $message
}

## continue main script
# Get event grid data
$data = $requestBody.data
$name = $data.name

Out-File -Encoding Ascii -FilePath $res -inputObject "hello $name"
write-output "hello $name"