Retrieve Azure Tenant Id using PowerShell

CodeSnippets #1

I have an idea to do a series of short blog posts over the year with helpful PowerShell functions, SQL code or problems I’ve encountered. The kind of thing I wouldn’t bother writing about as it would barely hit 200 words. I’d love some feedback on whether these “snippets” are helpful.

This is a very handy little function that I refer to on a regular basis when working with Azure and Power BI in PowerShell. The purpose of the function is to quickly retrieve the tenant Id of any Azure tenant based on the provided parameter. The user can provide a domain name or a valid email address. The function queries Azure anonymously so there’s no requirement to login first.

You can also find this up on my Github. PRs are always welcome!

Enjoy!

<#
.SYNOPSIS
Retrieve a domain's Azure tenant ID anonymously

.DESCRIPTION
This function will anonymously retrieve a domain's Azure tenant ID using a provided email containing the target domain or a domain itself.

.PARAMETER Domain
The full domain of the Azure tenant.

.PARAMETER Email
An email or user account that contains the domain of the Azure tenant

.EXAMPLE
Get-AzureTenantID -Domain craigporteous.com

Get-AzureTenantID -Email craig@craigporteous.com

.NOTES
General notes
#>

function Get-AzureTenantId{

    [CmdletBinding()]
    param
    (
        [ValidateScript({$_ -notmatch "@"})]
        [string]
        $domain,

        [ValidateScript({$_ -match "@"})]
        [string]
        $email
    )

    Process{
        if($domain){
            Write-Verbose 'Domain provided.'
        }
        elseif ($email) {
            Write-Verbose 'Split the string on the username to get the Domain.'
            $domain = $email.Split("@")[1]
        }
        else{
            throw
            Write-Warning 'You must provide a valid Domain or User email to proceed.'
        }

        Write-Verbose 'Query Azure anonymously.'
        $tenantId = (Invoke-WebRequest -UseBasicParsing https://login.windows.net/$($Domain)/.well-known/openid-configuration|ConvertFrom-Json).token_endpoint.Split('/')[3]

        return $tenantId
    }
}