(PowerShell) Microsoft Graph OAuth2 Client Credentials Grant Flow

Demonstrates how to get a Microsoft Graph access token using the Client Credentials Grant Flow.

You can use the OAuth 2.0 client credentials grant specified in RFC 6749, sometimes called two-legged OAuth, to access web-hosted resources by using the identity of an application. This type of grant is commonly used for server-to-server interactions that must run in the background, without immediate interaction with a user. These types of applications are often referred to as daemons or service accounts.

For more information, see https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-oauth2-client-creds-grant-flow

Chilkat .NET Downloads Chilkat .NET Assemblies

Add-Type -Path "C:\chilkat\ChilkatDotNet47-9.5.0-x64\ChilkatDotNet47.dll"

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

$http = New-Object Chilkat.Http

$req = New-Object Chilkat.HttpRequest
$req.AddParam("client_secret","CLIENT_SECRET")
$req.AddParam("client_id","CLIENT_ID")
# Don't know if the scopes valid for the client credentials grant are different than the scopes for the 3-legged Authorization Code Grant...
$req.AddParam("scope","https://graph.microsoft.com/.default")
$req.AddParam("grant_type","client_credentials")

# Use your own tenant ID, for example 4d8fdd66-66d1-43b0-ae5c-e31b4b7de5cd
$url = "https://login.microsoftonline.com/TENANT_ID/oauth2/v2.0/token"
$resp = $http.PostUrlEncoded($url,$req)
if ($http.LastMethodSuccess -ne $true) {
    $($http.LastErrorText)
    exit
}

$statusCode = $resp.StatusCode
$("Response status code = " + $statusCode)

$json = New-Object Chilkat.JsonObject
$json.Load($resp.BodyStr)

$json.EmitCompact = $false
$($json.Emit())

# Sample successful output:

# {
#   "token_type": "Bearer",
#   "expires_in": 3599,
#   "ext_expires_in": 3599,
#   "access_token": "eyJ0eX...K0jOERg"
# }

if ($statusCode -eq 200) {
    $json.WriteFile("qa_data/tokens/msGraphClientCredentialsToken.json")
    $("Success.")
}
else {
    $("Failed.")
}