ExpressJS / Heroku Application Error - node.js

Question

I am attempting to deploy a test express app on Heroku.
My package.json looks like this -
{
"name": "heroku-test-app",
"version": "1.0.0",
"description": "",
"main": "dist",
"scripts": {
"test": "cross-env NODE_ENV=test nodemon --exec mocha ./**/*.spec.js --compilers js:babel-core/register --require babel-polyfill",
"dev": "nodemon -w src --exec \"babel-node src --presets es2015,stage-0\"",
"build": "babel src -s -D -d dist --presets es2015,stage-0",
"start": "cross-env node dist",
"prestart": "npm run -s build",
"clean": "rimraf dist/"
},
"author": "",
"license": "ISC",
"dependencies": {
"babel-cli": "^6.26.0",
"babel-core": "^6.26.0",
"babel-eslint": "^7.2.3",
"babel-polyfill": "^6.26.0",
"babel-preset-es2015": "^6.24.1",
"babel-preset-stage-0": "^6.24.1",
"body-parser": "^1.17.2",
"cross-env": "^5.0.5",
"dotenv": "^4.0.0",
"express": "^4.15.4",
"morgan": "^1.8.2"
},
"devDependencies": {
"chai": "^4.1.1",
"mocha": "^3.5.0",
"nodemon": "^1.11.0",
"rimraf": "^2.6.1",
"supertest": "^3.0.0"
}
}
My Procfile looks like this -
web: npm start
and my test app is as so -
import express from 'express';
import morgan from 'morgan';
import bodyParser from 'body-parser';
const app = express();
const postBodyLimit = '100kb';
const port = 3000;
app.use(
morgan('combined', {
skip: (req, res) => res.statusCode < 400
})
);
app.use(bodyParser.json({ limit: postBodyLimit }));
app.use(bodyParser.urlencoded({ extended: false }));
app.get('/', (req, res) => res.status(200).json({ message: 'No unicorns here.' }));
// catch 404's and pass to our global error handler
app.all('*', (req, res, next) => {
const err = new Error('Not Found');
err.status = 404;
next(err);
});
app.use((err, req, res, next) => {
res.status(err.status || 500).json({
message: err.message,
error: app.get('env') === 'development' ? err : null
});
});
app.listen(port, () => console.log(`listening on port ${port}`));
export default app;
When running my app locally, it starts and works perfectly. When running heroku local web, it also works as expected.
When I deploy to heroku however, I get the application error page. However on streaming my logs, there is nothing to suggest it has crashed.
I have just deployed again now, this is the current log file
2017-08-28T06:38:40.000000+00:00 app[api]: Build succeeded
2017-08-28T06:39:03.959631+00:00 app[web.1]:
2017-08-28T06:39:03.959649+00:00 app[web.1]: > heroic-test-app#1.0.0 prestart /app
2017-08-28T06:39:03.959650+00:00 app[web.1]: > npm run -s build
2017-08-28T06:39:03.959651+00:00 app[web.1]:
2017-08-28T06:39:05.856118+00:00 app[web.1]: src/index.js -> dist/index.js
2017-08-28T06:39:05.898228+00:00 app[web.1]:
2017-08-28T06:39:05.898232+00:00 app[web.1]: > heroic-test-app#1.0.0 start /app
2017-08-28T06:39:05.898234+00:00 app[web.1]: > cross-env node dist
2017-08-28T06:39:05.898234+00:00 app[web.1]:
2017-08-28T06:39:06.654100+00:00 app[web.1]: listening on port 3000
2017-08-28T06:44:40.078283+00:00 app[web.1]:
2017-08-28T06:44:40.078319+00:00 app[web.1]: > heroic-test-app#1.0.0 prestart /app
2017-08-28T06:44:40.078320+00:00 app[web.1]: > npm run -s build
2017-08-28T06:44:40.078321+00:00 app[web.1]:
2017-08-28T06:44:42.379605+00:00 app[web.1]: src/index.js -> dist/index.js
2017-08-28T06:44:42.434704+00:00 app[web.1]:
2017-08-28T06:44:42.434707+00:00 app[web.1]: > heroic-test-app#1.0.0 start /app
2017-08-28T06:44:42.434708+00:00 app[web.1]: > cross-env node dist
2017-08-28T06:44:42.434709+00:00 app[web.1]:
2017-08-28T06:44:43.156940+00:00 app[web.1]: listening on port 3000
2017-08-28T06:45:39.332668+00:00 app[web.1]: Error waiting for process to terminate: No child processes
I am at a loss how to proceed at this point.

Answer 1

you shouldn't set the port of http server as 3000, you should use the port of process.env, heroku will set an PORT in process.env.
So you should use app.listen(process.env.PORT, () => {}).
and there is an err code about the heroku application, if you can provide that, it would be better.