Heroku 503 Service Unavailable - node.js

Question

I am currently building a simple CRUD app using ExpressJS, and host it on Heroku using free account.
The problem I ran into is:
GET API for getting all items works on localhost, but show status 503 when hosting on Heroku;
POST API for updating one item works on localhost, but same issue as GET API above;
All 503 errors are after 30s of loading, this should be a setting from Heroku.
I do have other API end points that work on both local and Heroku server:
GET API for getting one item using ID
My guessing:
The issue should not be a code issue
There is some issue when the code is deployed and Heroku cannot process this request
I tried to find some articles on the web but this seems hard to diagnose, anyone who has experience please let me know how I can solve this issue. Appreciate your comments.
My Mongoose Schema
const mongoose = require("mongoose");
const ThoughtSchema = mongoose.Schema({
title: {
type: String,
required: true
},
content: {
type: String,
required: true
},
date: {
type: Date,
default: Date.now
}
});
module.exports = mongoose.model("Thought", ThoughtSchema);
2 end points that do not work
// Returns all thoughts
router.get("/", async (req, res) => {
try {
const thought = await Thought.find();
res.json(thought);
} catch (err) {
res.json({ message: err });
}
});
// Submit a post
router.post("/", async (req, res) => {
const thought = new Thought({
title: req.body.title,
content: req.body.content
});
try {
const savedThought = await thought.save();
res.json(savedThought);
} catch (err) {
res.json({ message: err });
}
});
The end point that works
// Specific thought
router.get("/:thoughtId", async (req, res) => {
try {
const thought = await Thought.findById(req.params.thoughtId);
res.json(thought);
} catch (err) {
res.json({ message: err });
}
});
My package.json for this express app
{
"name": "my-thoughts-app",
"version": "0.1.0",
"description": "An app to records user's thoughts",
"main": "index.js",
"scripts": {
"start": "node index.js",
"test": "echo \"Error: no test specified\" && exit 1"
},
"repository": {
"type": "git",
"url": "git+https://github.com/PayneTang/my-thoughts-app.git"
},
"author": "Payne Tang",
"license": "ISC",
"bugs": {
"url": "https://github.com/PayneTang/my-thoughts-app/issues"
},
"homepage": "https://github.com/PayneTang/my-thoughts-app#readme",
"dependencies": {
"dotenv": "^8.2.0",
"express": "^4.17.1",
"mongoose": "^5.8.11"
},
"devDependencies": {
"typescript": "^3.7.5"
}
}
EDIT:
My index.js
const express = require("express");
const path = require("path");
const app = express();
const mongoose = require("mongoose");
const thoughtRoute = require("./routes/thought");
require("dotenv").config();
console.log(process.env);
// Mongoose settings
mongoose.connect(
process.env.DB_CONNECTION,
{ useNewUrlParser: true, useUnifiedTopology: true },
() => {
console.log("Connected to DB!");
}
);
app.use(express.json());
app.use((req, res, next) => {
res.header("Access-Control-Allow-Origin", "*");
res.header("Access-Control-Allow-Methods", "*");
res.header(
"Access-Control-Allow-Headers",
"Origin, X-Requested-With, Content-Type, Accept"
);
next();
});
app.use("/api/thought", thoughtRoute);
app.get("/api/test", (req, res) => {
res.send("hi");
});
// Serve client side
app.use(express.static(path.join(__dirname, "client/build")));
app.use(express.static(path.join(__dirname, "client/public")));
// app.get("*", (req, res) => {
// res.sendFile(path.join(__dirname, "client/build/index.html"));
// });
const PORT = process.env.PORT || 5000;
app.listen(PORT, () => {
console.log("Listening on port " + PORT + "...");
});

Answer 1

The root cause after checking is due to the access restriction from Heroku to Mongo atlas.
After adding 0.0.0.0/0 for IP whitelist, I am able to get data from MongoDB.
Reference: https://docs.atlas.mongodb.com/security-whitelist/#add-whitelist-entries

Answer 2

I had the same problem and I was able to fix it by doing these two steps:
Add node version to package.json file:
"engines": {
"node": "14.17.3"
}
}
I changed access settings in MongoDB, allowing access to the database from anywhere (basically, whitelisting 0.0.0.0/0 IP address)

Answer 3

In my case, the issue was in package.json I installed two new packages yesterday and in my package.json:
"engines": {
"node": "12.16.0"
},
I changed the version to the my current system version:
"engines": {
"node": "14.5.0"
},
this is how my 503 service unavailable error gone.

Answer 4

This can be caused in several ways to the Node app.
1- Make sure that you specify the right port as what heroku does is it runs our app on a dynamic port.
const PORT = process.env.PORT || 3000;
app.listen(PORT, err => {
if(err) throw err;
console.log("%c Server running", "color: green");
});
as described in this comment
https://stackoverflow.com/a/52992592/11887902
2- Make sure that you added the Procfile with
npm start
to start the application.
3- If you are using Nodemon and you install it globally, just make sure that you install it locally too.
Finally, just have a look at the logs of the project to figure what heppen to make your project not in the service.
These cases happened to me and caused this error.

Answer 5

My issue was caused due to case sensitivity that is at times ignored by node,
in my controllers I had a file named sessions.js yet when importing in my routes I had mistakenly put ... = require('../controllers/Sessions'),
Nodemon was running without issues as I was developing but upon deploying on heroku it crashed so I changed to ... = require('../controllers/sessions')
and now it runs ok