如果私钥未直接存储在应用程序脚本文件中，则服务帐户的Google Apps脚本OAuth2库错误

Question

我已成功使用服务帐户建立了从Google Apps脚本到Google Cloud firestore数据库的连接。 只要我将凭据存储在应用程序脚本文件本身中，它就可以正常工作。 如果我将凭据的私钥存储在其他地方（在数据库中，在驱动器文件中，则是google doc ...），则oauth2身份验证将失败，并显示以下错误：GAS Oauth2库抛出了“无效参数：密钥”。

我进行了进一步调查，似乎是编码/字符集问题。 如果我比较硬编码和存储在文件/数据库中的私钥字符串的长度，则密钥的长度不相等，但是密钥字符串似乎是相同的。

一些帮助，将不胜感激。

function createOAuth() {

// credentials of service account hard coded 
var jsonObj = {
      "type": "service_account",
      "project_id": "id of project",
 "private_key": "-----BEGIN PRIVATE KEY-----.....----END PRIVATE KEY-\n",
      "client_email": "servic accoutn email",
      "auth_uri": "https://accounts.google.com/o/oauth2/auth",
      "token_uri": "https://oauth2.googleapis.com/token",    
    }  

// not working if store attribute private_key somewhere else like:
/*var fileContent = DriveApp.getFileById('idOfFile').getBlob().getDataAsString("UTF-8"); //OR
DocumentApp.getBody().getText() //OR
var privateKey = Utilities.newBlob(privatKeyFromCredents).getDataAsString()
//store key in cloud firestore database also not working. 
*/

return OAuth2.createService("Service Account")
  .setTokenUrl('https://accounts.google.com/o/oauth2/token')
  .setPrivateKey(jsonObj.private_key)
  .setIssuer(jsonObj.client_email)
   .setPropertyStore(PropertiesService.getScriptProperties())
  .setCache(CacheService.getScriptCache())
  .setParam('access_type', 'offline')
  .setScope('https://www.googleapis.com/auth/script.external_request https://www.googleapis.com/auth/cloud-platform https://www.googleapis.com/auth/datastore');

var access = service.hasAccess(); // true if jsonObj is hard coded 
// false if stored somewhere else --> error: Invalid Argument: Key
Logger.log('Access: ' + access); 

}

Answer 1

// get Credentials form Drive in JSON format
var fileContent = DriveApp.getFileById('18t9NnzwKMlmQAnRUa_KovWdDvhk60oZT').getBlob().getDataAsString("UTF-8");

var serviceCredentials = JSON.parse(fileContent);
serviceCredentials['service_name'] = "Service Account Name";
serviceCredentials['scope'] = "https://www.googleapis.com/auth/script.external_request https://www.googleapis.com/auth/cloud-platform https://www.googleapis.com/auth/datastore ";

var service = OAuth2.createService(serviceCredentials.service_name)
.setTokenUrl(serviceCredentials.token_uri)
.setPrivateKey(serviceCredentials.private_key)
.setIssuer(serviceCredentials.client_email)
.setPropertyStore(PropertiesService.getUserProperties())
.setCache(CacheService.getUserCache())
.setParam('access_type', 'offline')
.setScope(serviceCredentials.scope);

// for testing if access oauth setup is working or not
var access = service.hasAccess();
Logger.log('Access: ' + access); //true or false