Adding GitHub OAuth login to an Express app

GitHub OAuth Setup

GitHub OAuth follows the same authorization code flow as Google. Register an OAuth App in GitHub Settings → Developer settings → OAuth Apps. Set the callback URL to http://localhost:3000/auth/github/callback.

npm install passport-github2

const GitHubStrategy = require('passport-github2').Strategy;

passport.use(new GitHubStrategy({
  clientID: process.env.GITHUB_CLIENT_ID,
  clientSecret: process.env.GITHUB_CLIENT_SECRET,
  callbackURL: '/auth/github/callback',
  scope: ['user:email']
}, async (accessToken, refreshToken, profile, done) => {
  const email = profile.emails && profile.emails[0]
    ? profile.emails[0].value
    : null;

  let user = await db.findByGithubId(profile.id);
  if (!user) {
    user = await db.createUser({
      githubId: profile.id,
      email,
      name: profile.displayName || profile.username
    });
  }
  return done(null, user);
}));

GitHub Email Gotcha

GitHub users can make their email private. Without the user:email scope, profile.emails will be empty. Even with the scope, the array can be empty if the user has no verified email. Always handle the null case and allow users to add an email later. Never require an email at social-login time if you cannot guarantee it will be present.