how-to-firebase-8-login.js

const function = require('firebase-functions');

functions.database.ref('queues/login/{uid}').onWrite(event => {
    const config = functions.config();
    // functions.config() returns your environment variables.
    // In this case I have an array of my admin users' email addresses in accessControlLists.adminUsers
    // It looks like ['[email protected]', '[email protected]']
    const adminUsersString = config.['access-control-lists']['admin-users'];
    const adminUsers = adminUsersString.split(',');
    const user = event.data.val();
    const userRef = event.data.adminRef.root.child('users').child(event.params.uid);

    if (!user) return Promise.resolve();

    user.lastLogin = Date.now();

    if (adminUsers.includes(user.email)) {
      user.isAdmin = true;
    }

    return userRef.update(user).then(() => {
      return event.data.ref.remove();
    });
  };
});