app.js

const express = require('express');
const cors = require('cors');
const bodyParser = require('body-parser');
const http = require('http');

const config = require('./src/config');
const { sequelize, models } = require('./src/models');
const routes = require('./src/routes');
const responses = require('./src/responses');

const app = express();

app.enable('trust proxy');

app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));
app.use(cors(config.cors));

const port = parseInt(process.env.PORT || config.port, 10); // Get port from environment

/* global */
global.config = config;
global.models = models;
global.sequelize = sequelize;
/* global */

/* configure port to app */
app.set('port', port);

/* Attaching custom response methods to res object */
app.use(responses);

/* configure routes */
routes(app);

// Make sure k8s health check does not fail
app.get('/healthz', (req, res) => {
  res.sendStatus(200);
});

// catch 404 and forward to error handler
app.use((req, res, next) => {
  const err = new Error('Not Found');
  err.status = 404;
  next(err);
});

app.use((error, req, res) => {
  console.error(error);

  res.status(error.status || 500);
  res.json({
    message: "Oops! Couldn't perform this action at the moment. Please try again",
    error
  });
});

/**
 * Create HTTP server.
 */
const server = http.createServer(app);

const isTest = process.env.NODE_ENV === 'test';
const isProduction = process.env.NODE_ENV === 'production';

/**
 * Bind onError and onListening handler
 */
server.on('error', error => {
  if (error.syscall !== 'listen') {
    throw error;
  }

  const bind = typeof port === 'string' ? `Pipe ${port}` : `Port ${port}`;

  // handle specific listen errors with friendly messages
  switch (error.code) {
    case 'EACCES':
      console.error(`${bind} requires elevated privileges`); // eslint-disable-line no-console
      process.exit(1);
      break;
    case 'EADDRINUSE':
      console.error(`${bind} is already in use`); // eslint-disable-line no-console
      process.exit(1);
      break;
    default:
      throw error;
  }
});

server.on('listening', () => {
  const addr = server.address();
  const bind = typeof addr === 'string' ? `pipe ${addr}` : `port ${addr.port}`;
  console.log(`Listening on ${bind}`);
});

function start(done) {
  sequelize.sync({ force: isTest }).then(async () => {
    if (isTest || isProduction) {
      // Setup testing/prod environment
    }

    /**
     * Listen on provided port, on all network interfaces.
     */
    server.listen(port, done);
  });
}

function lower(done) {
  server.close(done);
}

module.exports = {
  lower,
  start,
  sequelize,
  models,
  default: app
};