github.js

const loginWithGithub = async (req, res, next) => {
  try {
    // exchange "code" for a access token which never expire as of 201912
    const atoken_resp = await axios.post('https://github.com/login/oauth/access_token',
      {
        client_id: process.env.GITHUB_CLIENT_ID,
        client_secret: process.env.GITHUB_CLIENT_SECRET,
        code: req.body.code
      }
    );
    const parsed = queryString.parse(atoken_resp.data);
    const access_token = parsed.access_token;

    const user_resp = await axios.get('https://api.github.com/user', {
      headers: {
        'Authorization': "bearer " + access_token,
        'User-Agent': 'smartshoppinglist'
      }
    });

    const email_resp = await axios.get('https://api.github.com/user/public_emails', {
      headers: {
        'Authorization': "bearer " + access_token,
        'User-Agent': 'smartshoppinglist'
      }
    });

    req.email = email_resp.data[0].email;

    let profile = {
      email: email_resp.data[0].email,
      id: user_resp.data.id,
      name: user_resp.data.name,
      avatar_url: user_resp.data.avatar_url
    };

    await User.upsertGithubUser(profile);
  } catch (err) {
    console.log("====> github err: ", err);
    res.status(500).send({ auth: false, message: 'Failed to auth through github.' });
  }
  next();
}

const issueJwt = function (req, res, next) {
  let jwt_token = jwt.sign({ email: req.email },
    process.env.JWT_SECRET, 
    { expiresIn: 30 * 24 * 60 * 60 }// expires in 30 days
  );
  res.json({
    token: jwt_token
  });
  next();
}

app.post('/login/github', loginWithGithub, issueJwt, (req, res) => {});