REST_ACCESS_TOKEN_OAUTH2.js

%%[
SET @MID = '50000XXXX'
SET @apiCreds = LOOKUP('REST_Credentials', 'apiCreds', 'MID', @MID)
SET @apiCreds = DecryptSymmetric(@apiCreds, 'aes', 'INT_PWD', @null, 'INT_SALT', @null, 'INT_IV', @null)
]%%
  
<script runat="server">

Platform.Load("Core","1.1.1");
  
var apiCreds = Variable.GetValue('@apiCreds');
var credentialObj = Platform.Function.ParseJSON(apiCreds);

var clientId = credentialObj.clientId;
var clientSecret = credentialObj.clientSecret;
var authURL = credentialObj.authURL;
var tenantURL = authURL.substring(0,36);

/* Authentification */
var payload = {
        client_id: clientId,
        client_secret: clientSecret,
 		    grant_type: "client_credentials"
    };

var url = authURL + '/v2/token';  
var contentType = 'application/json';
var accessToken;

try {
   var accessTokenRequest = HTTP.Post(url, contentType, Stringify(payload));
   if(accessTokenRequest.StatusCode == 200) {
        var tokenResponse = Platform.Function.ParseJSON(accessTokenRequest.Response[0]);
        accessToken = tokenResponse.access_token;
   }
} catch (error) {
    Write(Stringify(error));
}