Google Shared Drive Viewers Automator

code.gs

/**
 * @OnlyCurrentDoc
 * 1. Create a new Google Sheet (https://sheet.new) and remove all but one column
 * 2. Add all of the email addresses in Column A that you'd like to have as viewers on the Shared Drive
 * 3. Click Tools → Script Editor and copy/paste all of this code into the editor
 * 4. Edit the Shared Drive ID on line 10 (https://drive.google.com/drive/folders/{Shared Drive ID})
 * 5. Click "▷ Run" in the top toolbar, allow authorization, and you're done!
 */

const sharedDriveId = '0AAt_DfuXH73UUA9dVp';

function updateMembers() {
  let sharedDrive = DriveApp.getFolderById(sharedDriveId); // get "folder" (Shared Drive) object via DriveApp
  let existingMemebers = sharedDrive.getViewers().map(e => e.getEmail()); // get it's viewers
  let desiredMembers = SpreadsheetApp.getActiveSheet().getDataRange().getValues().flat().filter(e => !!e).map(e => e.toLowerCase().trim()); // the spreadsheet cells (a flattened array of arrays), filtered out blanks
  let toAdd = desiredMembers.filter(x => !existingMemebers.includes(x)); // diff the two arrays to get emails that we need to add
  let toRemove = existingMemebers.filter(x => !desiredMembers.includes(x)); // and emails that need to be removed
  if (toAdd.length) console.log('Adding: ' + toAdd.join(', '));
  if (toRemove.length) console.log('Removing: ' + toRemove.join(', '));
  toAdd.forEach(email => { try {sharedDrive.addViewer(email)} catch(e) {console.warn(email + ': ' + e.message)} }); // attempt to add each
  toRemove.forEach(email => { try {sharedDrive.removeViewer(email)} catch(e) {console.warn(email + ': ' + e.message)} }); // and remove each
  if (ScriptApp.getScriptTriggers().length == 0) ScriptApp.newTrigger('updateMembers').timeBased().everyMinutes(15).create(); // then schedule to run this function every 15 minutes if it isn't already scheduled
}