Update a Google group to contain only one single member

group-rotation.js

/*
  This code is meant to be used with a rotating responsibility for incoming bugs and stuff.
  To make this work, you need to:
  1. Set up the key in the Google IAM manager
  2. Add domain delegation for the user
  3. Download the key and add the following fields: "admin_email" and "domain"
*/

var key = require('./google-people-api-creds.json');
var scope = ['https://www.googleapis.com/auth/admin.directory.group',
             'https://www.googleapis.com/auth/admin.directory.group.member',
             'https://www.googleapis.com/auth/admin.directory.user'];
var bluebird = require('bluebird');
var google = require('googleapis');

function updateGroup(groupName, userName) {
  var jwtClient = new google.auth.JWT(key.client_email, null, key.private_key, scope, key.admin_email);

  bluebird.promisifyAll(jwtClient);

  var client;
  var userKey, groupKey;

  return jwtClient.authorizeAsync()
    .then(function() {
      client = google.admin('directory_v1');
      bluebird.promisifyAll(client.users);
      bluebird.promisifyAll(client.groups);
      bluebird.promisifyAll(client.members);

      return client.members.listAsync({
        auth: jwtClient,
        groupKey: groupName + '@' + key.domain
      }).then(function(res) {
        // Delete all members
        return bluebird.all(res.members
          .filter(function(m) { return m.email != 'admin@' + key.domain; })
          .map(function(m) {
            console.log('Deleting user ' + m.email);
            return client.members.deleteAsync({
              auth: jwtClient,
              groupKey: groupName + '@' + key.domain,
              memberKey: m.email
            });
          }));
      }).then(function(res) {
        console.log('Deleted all users!');
        console.log('Adding user ' + userName);
        return client.members.insertAsync({
          auth: jwtClient,
          groupKey: groupName + '@' + key.domain,
          resource: {
            email: userName + '@' + key.domain
          }
        });
      });
    });
}

updateGroup('dev-goalie-rotation', 'selberg');