Provides the ability to retrieve an access token from an Azure AD Application

AzureRmAccessToken.ps1

function Get-AzureRmAccessToken {
    
    <#
    .SYNOPSIS
        Get-AzureRmAccessToken will retrieve an Access Token via Azure Active Directory.
    .DESCRIPTION
        Provides the ability to retrieve an Access Token from Azure Active Directory Application.
    .EXAMPLE
        Get-AzureRmAccessToken -TenantId $tenantId -ClientId $clientId -ClientSecret $clientSecret
    .LINK
        https://gist.github.com/ljtill
    #>

    [CmdletBinding()]
    param (
        [Parameter()]
        [string]$TenantId,

        [Parameter()]
        [string]$ClientId,

        [Parameter()]
        [string]$ClientSecret
    )

    begin {
        $request = @{
            Method = "POST"
            Uri = ("https://login.microsoftonline.com/" + $tenantId + "/oauth2/token")
            Headers = @{
                "Content-Type" = "application/x-www-form-urlencoded"
                "Accept" = "application/json"
            }
            Body = @{
                "grant_type" = "client_credentials"
                "client_id" = $clientId
                "client_secret" = $clientSecret
                "resource" = "https://management.azure.com/"
            }
        }
    }

    process {
        $response = Invoke-RestMethod @request
    }

    end {
        return $response.access_token
    }

}

TODO: Enhanced verbose output.