server.js

// app.js
import express from 'express';
import bodyParser from 'body-parser';
import methodOverride from 'method-override';
import session from 'express-session';
import cookieParser from 'cookie-parser';
import errorHandler from 'errorhandler';
import morgan from 'morgan';
import flash from 'connect-flash';

import passport from './passport';
import './db';
import routes from '../routes';

let app = express();

app.set('port', process.env.PORT || 3333);
app.use(cookieParser());
app.use(morgan('dev'));
app.use(
  bodyParser.urlencoded({
    extended: true,
  }),
);
app.use(bodyParser.json());
app.use(methodOverride());
app.use(
  session({
    secret: 'iBir9DL2G99OojUR',
    saveUninitialized: true,
    resave: true,
    cookie: { secure: true, expires: false },
  }),
);
app.use(passport.initialize());
app.use(passport.session());
app.use(flash());

app.use('/', routes);

if ('development' === app.get('env')) {
  app.use(errorHandler());
}

export default app;

// passport.js
import passport from 'passport';
import { Strategy as GitHubStrategy } from 'passport-github';
import User from '../models/User';

passport.use(
  new GitHubStrategy(
    {
      clientID: 'XXX',
      clientSecret: 'YYY',
      callbackURL: 'http://localhost:3333/auth/github/callback',
    },
    function(accessToken, refreshToken, profile, done) {
      User.findOne({ userId: profile.id }, (err, user) => {
        if (err) {
          return done(err);
        }
        if (!user) {
          const obj = {
            userId: profile.id,
            username: profile.username,
            fullname: profile.displayName,
            email: profile.emails[0].value,
            token: accessToken,
            avatar: profile.photos[0].value,
            profileUrl: profile.profileUrl,
            provider: 'github',
          };
          const user = new User(obj);
          user.save(err => {
            if (err) {
              console.log(err);
            }
            return done(err, user);
          });
        } else {
          return done(err, user);
        }
      });
    },
  ),
);

passport.serializeUser(function(user, done) {
  done(null, user._id);
});

passport.deserializeUser(function(id, done) {
  User.findById(id, (err, user) => {
    done(err, user);
  });
});

export default passport;

// routes.js
import { Router } from 'express';
import passport from 'passport';
import User from './models/User';

const router = Router();

router.get('/', (req, res) => {
  res.send('Hello!');
  console.log(req.session);
});

router.get('/auth/github', passport.authenticate('github'));

router.get(
  '/auth/github/callback',
  passport.authenticate('github', {
    successRedirect: '/',
    failureRedirect: '/auth/error',
    failureFlash: true,
  }),
);

router.get('/logout', (req, res) => {
  req.logout();
  res.redirect('/');
});

router.get('/account', ensureAuthenticated, function(req, res) {
  User.findById(req.session.passport.user, function(err, user) {
    if (err) {
      console.log(err); // handle errors
    } else {
      res.send(user);
    }
  });
});

function ensureAuthenticated(req, res, next) {
  if (req.isAuthenticated()) {
    return next();
  }
  res.redirect('/403');
}

export default router;