app.js

import Koa        from 'koa';
import logger     from 'koa-logger';
import bodyparser from 'koa-bodyparser';
import error      from 'koa-error';
import convert    from 'koa-convert';
import Debug      from 'debug';

import config     from './lib/config';
import db         from './lib/db';
import router     from './lib/router';

export const app = module.exports = new Koa();
const debug      = new Debug('app:main');

app.use(convert(error()));
app.use(logger());
app.use(bodyparser());

app.use(config(app));
app.use(db(app));
app.use(router(app));

if (!module.parent) {
  app.listen(app.config.app.port, app.config.app.host, function cb() {
    debug(`Listen ${app.config.app.host}:${app.config.app.port}`);
  });
}

server.js

require('babel-core/register');
require('babel-polyfill');

const Debug = require('debug');

const app = require('./app');
const debug = new Debug('app:main');

app.listen(app.config.app.port, app.config.app.host, function cb() {
  debug(`Listen ${app.config.app.host}:${app.config.app.port}`);
});