Node JS gitlab webhook receiver and trigger pipelines

main.js

const qs = require('querystring');
const http = require('http');
const https = require('https');
const assert = require('assert');

const config = {
  port: 3000,
  projectId: '',
  pipelineTriggerToken: '',
  secretToken: null
};
assert(config.projectId, 'projectId must not empty');
assert(config.pipelineTriggerToken, 'pipelineTriggerToken must not empty');

server = http.createServer((req, res) => {
  new Promise((resolve, reject) => {
    res.writeHead(200, {'Content-Type': 'application/json'});
    if (req.method === 'POST') {
      verifyToken(req.headers);
      let body = '';
      req.on('data', data => {
        body += data;
      });
      req.on('end', () => {
        try {
          resolve({body: JSON.parse(body), headers: req.headers});
        } catch (error) {
          reject(error);
        }
      });
      req.on('error', error => {
        reject(error);
      });
    }
  })
    .then(({body}) => {
      switch (body.object_kind) {
        case 'merge_request':
          processMergeRequestEvent(body);
          break;
      }
      res.end(JSON.stringify({message: 'nodejs gitlab Webhook receiver'}));
      res.writeHead(200, {'Content-Type': 'application/json'});
    })
    .catch(error => {
      res.writeHead(500, {'Content-Type': 'application/json'});
      res.end(JSON.stringify({message: typeof error === 'object' && error.message ? error.message : 'Internal server error!'}));
    });
});

server.listen(config.port, () => {
  console.log('Listening on port ' + config.port);
});

function processMergeRequestEvent(body) {
  let ref;
  switch (body.object_attributes.state) {
    case 'opened':
      ref = body.object_attributes.source_branch;
      break;
    case 'merged':
      ref = body.object_attributes.target_branch;
      break;
  }
  if (!ref) {
    return;
  }
  post({ref})
    .then(console.info.bind(console, 'Trigger pipelines success with response:'))
    .catch(console.error.bind(console, 'Trigger pipelines with error:'));
}

function verifyToken(headers) {
  if (!config.secretToken) {
    return;
  }
  if (!headers['x-gitlab-token'] || headers['x-gitlab-token'] !== config.secretToken) {
    throw new Error('Secret token miss match');
  }
}

function post(data) {
  return new Promise((resolve, reject) => {
    data['token'] = config.pipelineTriggerToken;
    const requestData = qs.stringify(data);

    const requestOptions = {
      host: 'gitlab.com',
      port: 443,
      path: `/api/v4/projects/${config.projectId}/trigger/pipeline`,
      method: 'POST',
      headers: {
        'Content-Type': 'multipart/form-data',
        'Content-Length': Buffer.byteLength(requestData)
      }
    };

    const request = https.request(requestOptions, res => {
      res.setEncoding('utf8');
      let body = '';
      res.on('data', data => {
        body += data;
      });
      res.on('end', () => {
        try {
          resolve({body: JSON.parse(body), headers: res.headers});
        } catch (error) {
          reject(error);
        }
      });
      res.on('error', error => {
        reject(error);
      });
    });

    request.write(requestData);
    request.end();
  });
}