Generate-Auth-Token.ps1

#This function generate auth token using azure sdk
Function GetAuthTokenUsingAzureSdk {
    Param (
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$apiEndpointUri,         
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$tenantId,
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$applicationId,
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$secret
    )
    try {
        $adal = "${env:ProgramFiles(x86)}\Microsoft SDKs\Azure\PowerShell\ServiceManagement\Azure\Services\Microsoft.IdentityModel.Clients.ActiveDirectory.dll"
        [System.Reflection.Assembly]::LoadFrom($adal) | Out-Null
        $authorityUri = "https://login.microsoftonline.com/$tenantId/oauth2/token"    
        $authContext = New-Object "Microsoft.IdentityModel.Clients.ActiveDirectory.AuthenticationContext" -ArgumentList $authorityUri
        $credential = New-Object "Microsoft.IdentityModel.Clients.ActiveDirectory.ClientCredential" -ArgumentList $applicationId, $secret    
        return $authContext.AcquireTokenAsync($apiEndpointUri, $credential).Result.AccessToken;
    }
    catch {
        throw
    }
} 

#This function generate auth token using REST api
Function GetAuthTokenInvokingRestApi {
 
    Param(
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$tenantId,
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$applicationId,
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [String]$secret,
        [Parameter(Mandatory)][ValidateNotNull()][ValidateNotNullOrEmpty()]
        [string]$apiEndpointUri
    )
    $encodedSecret = [System.Web.HttpUtility]::UrlEncode($secret) 
    $RequestAccessTokenUri = "https://login.microsoftonline.com/$tenantId/oauth2/token"
    $body = "grant_type=client_credentials&client_id=$applicationId&client_secret=$encodedSecret&resource=$apiEndpointUri"
    $contentType = 'application/x-www-form-urlencoded'
    try {
        $Token = Invoke-RestMethod -Method Post -Uri $RequestAccessTokenUri -Body $body -ContentType $contentType
        Write-Output $Token
    }
    catch { throw }
}


$apiEndpointUri = "https://management.azure.com/"
$tenantId = "xxxxxx-xxxxx-xxxx-xxx-xxxx" 
$applicationId = "xxxx-xxxx-xxxx-xxxx-xxxxx"
$secret = "xxxxxxxxxx"

$authToken = GetAuthTokenUsingAzureSdk -apiEndpointUri $apiEndpointUri -tenantId $tenantId -applicationId $applicationId -secret $secret
if (-not $authToken) { throw "One of the provided login information is invalid 'tenantId: $tenantId', 'applicationId: $applicationId', 'secret: $secret' " }	  

Write-Host "Auth token by GetAuthTokenUsingAzureSdk :"
Write-Host $authToken -ForegroundColor Yellow

Write-Host "---------------------------------------"

$authToken = GetAuthTokenInvokingRestApi -apiEndpointUri $apiEndpointUri -tenantId $tenantId -applicationId $applicationId -secret $secret
if (-not $authToken) { throw "One of the provided login information is invalid 'tenantId: $tenantId', 'applicationId: $applicationId', 'secret: $secret' " }	  

Write-Host "Auth token by GetAuthTokenInvokingRestApi :"
Write-Host $authToken -ForegroundColor Yellow