Is my Windows Server up to date? Let's check it with latest Windows image tags from MCR :-) 🐳

is-my-server-up-to-date.ps1

$ErrorActionPreference = 'Stop'

# fetch the current version number from host
$current=(Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion")
$currUBR=$current.UBR

# fetch the maximum version number from MCR by filtering and sorting the JSON result
$prefix="$($current.CurrentMajorVersionNumber).$($current.CurrentMinorVersionNumber).$($current.CurrentBuildNumber)."
$json=$(Invoke-WebRequest -UseBasicParsing https://mcr.microsoft.com/v2/windows/servercore/tags/list | ConvertFrom-Json)
$hubUBR=($json.tags | Where-Object -FilterScript { $_.StartsWith($prefix) -and $_ -Match "^\d+\.\d+\.\d+\.\d+$" } |%{[System.Version]$_}|sort)[-1].Revision

Write-Output "Host Update Build Revision $currUBR, Hub Update Build Revision $hubUBR"

if ($currUBR -Lt $hubUBR) {
  Write-Error "Your host has update revision $currUBR, but should be updated to $hubUBR!"
} else {
  Write-Output "Your host seems up to date."
}