GTM Backup Script for Google Sheets

GTM Backup Script for Google Sheets.js

function getAccounts() {
  var accountList = TagManager.Accounts.list();
  for (var i = 0;i < accountList.account.length;i++) {
    //if (accountList.account[i].accountId > 123456) { //if you reach a timeout, resume by manually updating this and re-running
      getContainers(accountList.account[i].accountId,accountList.account[i].name);
      Utilities.sleep(5000); //GTM only allows 25 queries per 100 seconds, so we have to slow it down
    //}
  }
}

function getContainers(accountId,accountName) {
  try {
    var containerList = TagManager.Accounts.Containers.list('accounts/' + accountId);
    for (var i = 0;i < containerList.container.length;i++) {
      getBackup(accountId,accountName,containerList.container[i].containerId);
      Utilities.sleep(5000); //GTM only allows 25 queries per 100 seconds, so we have to slow it down
    }
  }catch(e){}
}

function getBackup(accountId,accountName,containerId) {
  var spreadsheet = SpreadsheetApp.getActive();
  var sheet = spreadsheet.getActiveSheet();
  try {
  var containerBackup = TagManager.Accounts.Containers.Versions.live('accounts/' + accountId + '/containers/' + containerId);
  sheet.appendRow([
    accountName,containerBackup.container.name,accountId,containerId,JSON.stringify(containerBackup)
  ]);
  }catch(e){
   sheet.appendRow([
     accountName,'',accountId,containerId,'ERROR'
     ]);
  }
}

Remember that you must enable GTM v2 API via Resources > Advanced Google Services and turn on in the Cloud Platform project too.