You should never ever run directly against Node.js in production.

You should never ever run directly against Node.js in production.

You should never ever run directly against Node.js in production

Sometimes I wonder if I know much of anything at all.

Just a few weeks ago I was talking to a friend who mentioned off-hand, “you would never run an application directly against Node in production”. I nodded vigorously to signal that I also would never ever run against Node in production because…hahaha….everyone knows that. But I didn’t know that! Should I have known that?!?? AM I STILL ALLOWED TO PROGRAM?

If I was to draw a Venn Diagram of what I know vs what I feel like everyone else knows, it would look like this…

By the way, that tiny dot gets smaller the older I get.

There is a better diagram created by Alicia Liu that kind of changed my life. She says that it’s more like this…

I love this diagram so much because I want it to be true. I don’t want to spend the rest of my life as a tiny, shrinking blue dot of insignificance.

SO DRAMATIC. Blame Pandora. I don’t control what gets played next while I’m writing this article and Dashboard Confessional is a helluva drug.

Well, assuming that Alicia’s diagram is true, I would like to share with you what I now know about running Node apps in production. Perhaps our relative Venn Diagrams don’t overlap on this subject.

First off, let’s address the statement “never run apps directly against Node in production”.

Never run directly against Node in production

Maybe. But maybe not. Let’s talk about the reasoning behind this statement. First, let’s look at why not.

Say we have a simple Express server. The simplest Express server I can think of…

We would run this with a start script in the package.json file.

"scripts": {  "start": "node index.js",  "test": "pfffft"}

There are sort of two problems here. The first is a development problem and the second is a production problem.

The development problem is that when we change the code, we have to stop and start the application to get our changes picked up.

To solve that, we usually use some sort of Node process manager like supervisor or nodemon. These packages will watch our project and restart our server whenever we make changes. I usually do that like this…

"scripts": {  "dev": "npx supervisor index.js",  "start": "node index.js"}

Then I run npm run dev. Note that I’m running npx supervisor here which allows me to use the supervisor package without having to install it. I ❤️ 2019. Mostly.

Our other problem is that we’re still running directly against Node and we already said that was bad and now we’re about to find out why.

I’m going to add another route here that attempts to read a file from disk that does not exist. This is an error that could easily show up in any real-world application.

If we run this directly against Node with npm start and navigate to the read endpoint, we get an error because that file doesn’t exist.

Which — no big deal right? It’s one error. It happens.

NO. Big deal. If you go back to your terminal you will see that the application is completely down.

Which means if you go back to the browser and try to go to the root URL of the site, you get the same error page. One error in one method took the application down for everyone.

That’s bad. Like really bad. This is one of the main reasons why people say “never run directly against Node in production”.

OK. So if we can’t run against Node in production, what is the right way to run Node in production?

Options for production Node

We’ve got a few options.

One of them would be to simply use something like supervisor or nodemon in production the same way we are using them in dev. That would work, but these tools are a little on the lightweight side. A better option is something called pm2.

pm2 the rescue

pm2 is a Node process manager that has lots of bells and whistles. Just like everything else “JavaScript”, you install it (globally) from npm — or you can just use npx again. I don’t want to tell you how to live your life.

There are a lot of ways to run your app with pm2. The simplest way is to just call pm2 start on your entry point.

"scripts": {  "start": "pm2 start index.js",  "dev": "npx supervisor index.js"},

And you’ll see something like this in the terminal…

That’s our process running in the background monitored by pm2. If you visit the read endpoint and crash the application, pm2 will automatically restart it. You won’t see any of that in the terminal because it’s running in the background. If you want to watch pm2 do its thing, you gotta run pm2 log 0. The 0 is the ID of the process we want to see logs for.

There we go! You can see pm2 restart the application when it goes down because of our unhandled error.

We can also pull out our dev command and have pm2 watch files for us and restart on any changes.

"scripts": {  "start": "pm2 start index.js --watch",  "dev": "npx supervisor index.js"},

Note that because pm2 runs things in the background, you can’t just ctrl+c your way out of a running pm2 process. You have to stop it by passing the ID or the name.

pm2 stop 0

pm2 stop index

Also, note that pm2 retains a reference to the process so you can restart it.

If you want to delete that process reference, you need to run pm2 delete. You can stop and delete a process in one command with delete.

pm2 delete index

We can also use pm2 to run multiple processes of our application. pm2 will automatically balance the load across those instances.

Multiple processes with pm2 fork mode

pm2 has a ton of configuration options and those are contained in an “ecosystem” file. To create one, run pm2 init. You’ll get something like this…

I’m going to ignore the “deploy” section in this article because I have no idea what it does.

The “apps” section is where you define the apps you want pm2 to run and monitor. You can run more than one. A lot of these configuration settings are probably self-explanatory. The one that I want to focus on here is the instances setting.

pm2 can run multiple instances of your application. You can pass in a number of instances that you want to run and pm2 will spin up that many. So if we wanted to run 4 instances, we could have the following configuration file.

Then we just run it with pm2 start.

pm2 is now running in “cluster” mode. Each of these processes is running on a different CPU on my machine, depending on how many cores I have. If we wanted to run a process for each core without knowing how many cores we have, we can just pass the max parameter to the instances value.

{   ...   instances: "max",   ...}

Let’s find out how many cores I’ve got in this machine.

8 CORES! Holy crap. I’m gonna install Subnautica on my Microsoft issued machine. Don’t tell them I said that.

The good thing about running processes on separate CPU’s is that if you have a process that runs amok and takes up 100% of the CPU, the others will still function. If you pass in more instances than you have cores, pm2 will double up processes on CPU’s as necessary.

You can do a WHOLE lot more with pm2, including monitoring and otherwise wrangling those pesky environment variables.

One other item of note: if for some reason you want pm2 to run your npm start script, you can do that by running npm as the process and passing the -- start. The space before the “start” is super important here.

pm2 start npm -- start

In Azure AppService, we include pm2 by default in the background. If you want to use pm2 in Azure, you don’t need to include it in your package.json file. You can just add an ecosystem file and you’re good to go.

OK! Now that we’ve learned all about pm2, let’s talk about why you may not want to use it and it might indeed be ok to run directly against Node.

Running directly against Node in production

I had some questions on this so I reached out to Tierney Cyren who is part of the enormous orange circle of knowledge, especially when it comes to Node.

Tierney pointed out a few drawbacks to using Node based process managers like pm2.

The main reason is that you shouldn’t use Node to monitor Node. You don’t want to use the thing that you are monitoring to monitor that thing. It’s kind of like you asking my teenage son to supervise himself on a Friday night: Will that end badly? It might, and it might not. But you’re about to find out the hard way.

Tierney recommends that you not have a Node process manager running your application at all. Instead, have something at a higher level which watches multiple separate instances of your application. For example, an ideal setup would be if you had a Kubernetes cluster with your app running on separate containers. Kubernetes can then monitor those containers and if any of them go down, it can bring them back and report on their health.

In this case, you can run directly against Node because you are monitoring at a higher level.

As it turns out, Azure is already doing this. If we don’t push a pm2 ecosystem file to Azure, it will start the application with our package.json file start script and we can run directly against Node.

"scripts": {  "start": "node index.js"}

In this case, we are running directly against Node and it’s OK. If the application were to crash, you’ll notice that it comes back. That’s because in Azure, your app runs in a container. Azure is orchestrating the container in which your app is running and knows when it faceplants.

But you still only have one instance here. It takes the container a second to come back online after it crashes meaning that there could be a few seconds of downtime for your users.

Ideally, you would want more than one container running. The solution to this would be to deploy multiple instances of your application to multiple Azure AppService sites and then use Azure Front Door to load balance the apps behind a single IP address. Front Door will know when a container is down and will route traffic to other healthy instances of your application.

Azure Front Door Service | Microsoft Azure
_Deliver, protect and track the performance of your globally distributed microservice applications with Azure Front Door…_azure.microsoft.com

systemd

Another suggestion that Tierney had is to run Node with systemd. I don’t understand too much (or anything at all) about systemd and I’ve already messed this phrasing up once already, so I’ll let Tierney say it in his own words…

This option is only possible if you have access to Linux in your deployment and you control the way that Node is started on a service level. If you’re running your Node.js process in a long-running Linux VM, like Azure VMs, you’re in a good place to run Node.js with systemd. If you are just deploying your files to a service like Azure AppService or Heroku or running inside of a containerized environment like Azure Container Instances, you should probably steer clear of this option.

Running Your Node.js App With Systemd - Part 1
_You've written the next great application, in Node, and you are ready to unleash it upon the world. Which means you can…_nodesource.com

Node.js Worker Threads

Tierney also wants you to know that Worker Threads are coming in Node. This will allow you to start your app on multiple “workers” (threads) thusly negating the need for something like pm2. Maybe. I don’t know. I didn’t really read the article.

Node.js v11.14.0 Documentation
_The worker_threads module enables the use of threads that execute JavaScript in parallel. To access it: const worker =…_nodejs.org

Be an Adult

Tierney’s last suggestion was to just handle the error and write some tests like an adult. But who has time for that?

The tiny circle abides

Now you know most of what is in the tiny blue circle. The rest is just useless facts about emo bands and beer.

For more information on pm2, Node and Azure, check out the following resources…

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Top 7 Most Popular Node.js Frameworks You Should Know

Top 7 Most Popular Node.js Frameworks You Should Know

Node.js is an open-source, cross-platform, runtime environment that allows developers to run JavaScript outside of a browser. In this post, you'll see top 7 of the most popular Node frameworks at this point in time (ranked from high to low by GitHub stars).

Node.js is an open-source, cross-platform, runtime environment that allows developers to run JavaScript outside of a browser.

One of the main advantages of Node is that it enables developers to use JavaScript on both the front-end and the back-end of an application. This not only makes the source code of any app cleaner and more consistent, but it significantly speeds up app development too, as developers only need to use one language.

Node is fast, scalable, and easy to get started with. Its default package manager is npm, which means it also sports the largest ecosystem of open-source libraries. Node is used by companies such as NASA, Uber, Netflix, and Walmart.

But Node doesn't come alone. It comes with a plethora of frameworks. A Node framework can be pictured as the external scaffolding that you can build your app in. These frameworks are built on top of Node and extend the technology's functionality, mostly by making apps easier to prototype and develop, while also making them faster and more scalable.

Below are 7of the most popular Node frameworks at this point in time (ranked from high to low by GitHub stars).

Express

With over 43,000 GitHub stars, Express is the most popular Node framework. It brands itself as a fast, unopinionated, and minimalist framework. Express acts as middleware: it helps set up and configure routes to send and receive requests between the front-end and the database of an app.

Express provides lightweight, powerful tools for HTTP servers. It's a great framework for single-page apps, websites, hybrids, or public HTTP APIs. It supports over fourteen different template engines, so developers aren't forced into any specific ORM.

Meteor

Meteor is a full-stack JavaScript platform. It allows developers to build real-time web apps, i.e. apps where code changes are pushed to all browsers and devices in real-time. Additionally, servers send data over the wire, instead of HTML. The client renders the data.

The project has over 41,000 GitHub stars and is built to power large projects. Meteor is used by companies such as Mazda, Honeywell, Qualcomm, and IKEA. It has excellent documentation and a strong community behind it.

Koa

Koa is built by the same team that built Express. It uses ES6 methods that allow developers to work without callbacks. Developers also have more control over error-handling. Koa has no middleware within its core, which means that developers have more control over configuration, but which means that traditional Node middleware (e.g. req, res, next) won't work with Koa.

Koa already has over 26,000 GitHub stars. The Express developers built Koa because they wanted a lighter framework that was more expressive and more robust than Express. You can find out more about the differences between Koa and Express here.

Sails

Sails is a real-time, MVC framework for Node that's built on Express. It supports auto-generated REST APIs and comes with an easy WebSocket integration.

The project has over 20,000 stars on GitHub and is compatible with almost all databases (MySQL, MongoDB, PostgreSQL, Redis). It's also compatible with most front-end technologies (Angular, iOS, Android, React, and even Windows Phone).

Nest

Nest has over 15,000 GitHub stars. It uses progressive JavaScript and is built with TypeScript, which means it comes with strong typing. It combines elements of object-oriented programming, functional programming, and functional reactive programming.

Nest is packaged in such a way it serves as a complete development kit for writing enterprise-level apps. The framework uses Express, but is compatible with a wide range of other libraries.

LoopBack

LoopBack is a framework that allows developers to quickly create REST APIs. It has an easy-to-use CLI wizard and allows developers to create models either on their schema or dynamically. It also has a built-in API explorer.

LoopBack has over 12,000 GitHub stars and is used by companies such as GoDaddy, Symantec, and the Bank of America. It's compatible with many REST services and a wide variety of databases (MongoDB, Oracle, MySQL, PostgreSQL).

Hapi

Similar to Express, hapi serves data by intermediating between server-side and client-side. As such, it's can serve as a substitute for Express. Hapi allows developers to focus on writing reusable app logic in a modular and prescriptive fashion.

The project has over 11,000 GitHub stars. It has built-in support for input validation, caching, authentication, and more. Hapi was originally developed to handle all of Walmart's mobile traffic during Black Friday.

Node.js for Beginners - Learn Node.js from Scratch (Step by Step)

Node.js for Beginners - Learn Node.js from Scratch (Step by Step)

Node.js for Beginners - Learn Node.js from Scratch (Step by Step) - Learn the basics of Node.js. This Node.js tutorial will guide you step by step so that you will learn basics and theory of every part. Learn to use Node.js like a professional. You’ll learn: Basic Of Node, Modules, NPM In Node, Event, Email, Uploading File, Advance Of Node.

Node.js for Beginners

Learn Node.js from Scratch (Step by Step)

Welcome to my course "Node.js for Beginners - Learn Node.js from Scratch". This course will guide you step by step so that you will learn basics and theory of every part. This course contain hands on example so that you can understand coding in Node.js better. If you have no previous knowledge or experience in Node.js, you will like that the course begins with Node.js basics. otherwise if you have few experience in programming in Node.js, this course can help you learn some new information . This course contain hands on practical examples without neglecting theory and basics. Learn to use Node.js like a professional. This comprehensive course will allow to work on the real world as an expert!
What you’ll learn:

  • Basic Of Node
  • Modules
  • NPM In Node
  • Event
  • Email
  • Uploading File
  • Advance Of Node

How to Use Express.js, Node.js and MongoDB.js

How to Use Express.js, Node.js and MongoDB.js

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

In this post, I will show you how to use Express.js, Node.js and MongoDB.js. We will be creating a very simple Node application, that will allow users to input data that they want to store in a MongoDB database. It will also show all items that have been entered into the database.

Creating a Node Application

To get started I would recommend creating a new database that will contain our application. For this demo I am creating a directory called node-demo. After creating the directory you will need to change into that directory.

mkdir node-demo
cd node-demo

Once we are in the directory we will need to create an application and we can do this by running the command
npm init

This will ask you a series of questions. Here are the answers I gave to the prompts.

The first step is to create a file that will contain our code for our Node.js server.

touch app.js

In our app.js we are going to add the following code to build a very simple Node.js Application.

var express = require("express");
var app = express();
var port = 3000;
 
app.get("/", (req, res) => {
  res.send("Hello World");
});
 
app.listen(port, () => {
  console.log("Server listening on port " + port);
});

What the code does is require the express.js application. It then creates app by calling express. We define our port to be 3000.

The app.use line will listen to requests from the browser and will return the text “Hello World” back to the browser.

The last line actually starts the server and tells it to listen on port 3000.

Installing Express

Our app.js required the Express.js module. We need to install express in order for this to work properly. Go to your terminal and enter this command.

npm install express --save

This command will install the express module into our package.json. The module is installed as a dependency in our package.json as shown below.

To test our application you can go to the terminal and enter the command

node app.js

Open up a browser and navigate to the url http://localhost:3000

You will see the following in your browser

Creating Website to Save Data to MongoDB Database

Instead of showing the text “Hello World” when people view your application, what we want to do is to show a place for user to save data to the database.

We are going to allow users to enter a first name and a last name that we will be saving in the database.

To do this we will need to create a basic HTML file. In your terminal enter the following command to create an index.html file.

touch index.html

In our index.html file we will be creating an input filed where users can input data that they want to have stored in the database. We will also need a button for users to click on that will add the data to the database.

Here is what our index.html file looks like.

<!DOCTYPE html>
<html>
  <head>
    <title>Intro to Node and MongoDB<title>
  <head>

  <body>
    <h1>Into to Node and MongoDB<&#47;h1>
    <form method="post" action="/addname">
      <label>Enter Your Name<&#47;label><br>
      <input type="text" name="firstName" placeholder="Enter first name..." required>
      <input type="text" name="lastName" placeholder="Enter last name..." required>
      <input type="submit" value="Add Name">
    </form>
  <body>
<html>

If you are familiar with HTML, you will not find anything unusual in our code for our index.html file. We are creating a form where users can input their first name and last name and then click an “Add Name” button.

The form will do a post call to the /addname endpoint. We will be talking about endpoints and post later in this tutorial.

Displaying our Website to Users

We were previously displaying the text “Hello World” to users when they visited our website. Now we want to display our html file that we created. To do this we will need to change the app.use line our our app.js file.

We will be using the sendFile command to show the index.html file. We will need to tell the server exactly where to find the index.html file. We can do that by using a node global call __dirname. The __dirname will provide the current directly where the command was run. We will then append the path to our index.html file.

The app.use lines will need to be changed to
app.use("/", (req, res) => {   res.sendFile(__dirname + "/index.html"); });

Once you have saved your app.js file, we can test it by going to terminal and running node app.js

Open your browser and navigate to “http://localhost:3000”. You will see the following

Connecting to the Database

Now we need to add our database to the application. We will be connecting to a MongoDB database. I am assuming that you already have MongoDB installed and running on your computer.

To connect to the MongoDB database we are going to use a module called Mongoose. We will need to install mongoose module just like we did with express. Go to your terminal and enter the following command.
npm install mongoose --save

This will install the mongoose model and add it as a dependency in our package.json.

Connecting to the Database

Now that we have the mongoose module installed, we need to connect to the database in our app.js file. MongoDB, by default, runs on port 27017. You connect to the database by telling it the location of the database and the name of the database.

In our app.js file after the line for the port and before the app.use line, enter the following two lines to get access to mongoose and to connect to the database. For the database, I am going to use “node-demo”.

var mongoose = require("mongoose"); mongoose.Promise = global.Promise; mongoose.connect("mongodb://localhost:27017/node-demo");

Creating a Database Schema

Once the user enters data in the input field and clicks the add button, we want the contents of the input field to be stored in the database. In order to know the format of the data in the database, we need to have a Schema.

For this tutorial, we will need a very simple Schema that has only two fields. I am going to call the field firstName and lastName. The data stored in both fields will be a String.

After connecting to the database in our app.js we need to define our Schema. Here are the lines you need to add to the app.js.
var nameSchema = new mongoose.Schema({   firstName: String,   lastNameName: String });

Once we have built our Schema, we need to create a model from it. I am going to call my model “DataInput”. Here is the line you will add next to create our mode.
var User = mongoose.model("User", nameSchema);

Creating RESTful API

Now that we have a connection to our database, we need to create the mechanism by which data will be added to the database. This is done through our REST API. We will need to create an endpoint that will be used to send data to our server. Once the server receives this data then it will store the data in the database.

An endpoint is a route that our server will be listening to to get data from the browser. We already have one route that we have created already in the application and that is the route that is listening at the endpoint “/” which is the homepage of our application.

HTTP Verbs in a REST API

The communication between the client(the browser) and the server is done through an HTTP verb. The most common HTTP verbs are
GET, PUT, POST, and DELETE.

The following table explains what each HTTP verb does.

HTTP Verb Operation
GET Read
POST Create
PUT Update
DELETE Delete

As you can see from these verbs, they form the basis of CRUD operations that I talked about previously.

Building a CRUD endpoint

If you remember, the form in our index.html file used a post method to call this endpoint. We will now create this endpoint.

In our previous endpoint we used a “GET” http verb to display the index.html file. We are going to do something very similar but instead of using “GET”, we are going to use “POST”. To get started this is what the framework of our endpoint will look like.

app.post("/addname", (req, res) => {
 
});
Express Middleware

To fill out the contents of our endpoint, we want to store the firstName and lastName entered by the user into the database. The values for firstName and lastName are in the body of the request that we send to the server. We want to capture that data, convert it to JSON and store it into the database.

Express.js version 4 removed all middleware. To parse the data in the body we will need to add middleware into our application to provide this functionality. We will be using the body-parser module. We need to install it, so in your terminal window enter the following command.

npm install body-parser --save

Once it is installed, we will need to require this module and configure it. The configuration will allow us to pass the data for firstName and lastName in the body to the server. It can also convert that data into JSON format. This will be handy because we can take this formatted data and save it directly into our database.

To add the body-parser middleware to our application and configure it, we can add the following lines directly after the line that sets our port.

var bodyParser = require('body-parser');
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
Saving data to database

Mongoose provides a save function that will take a JSON object and store it in the database. Our body-parser middleware, will convert the user’s input into the JSON format for us.

To save the data into the database, we need to create a new instance of our model that we created early. We will pass into this instance the user’s input. Once we have it then we just need to enter the command “save”.

Mongoose will return a promise on a save to the database. A promise is what is returned when the save to the database completes. This save will either finish successfully or it will fail. A promise provides two methods that will handle both of these scenarios.

If this save to the database was successful it will return to the .then segment of the promise. In this case we want to send text back the user to let them know the data was saved to the database.

If it fails it will return to the .catch segment of the promise. In this case, we want to send text back to the user telling them the data was not saved to the database. It is best practice to also change the statusCode that is returned from the default 200 to a 400. A 400 statusCode signifies that the operation failed.

Now putting all of this together here is what our final endpoint will look like.

app.post("/addname", (req, res) => {
  var myData = new User(req.body);
  myData.save()
    .then(item => {
      res.send("item saved to database");
    })
    .catch(err => {
      res.status(400).send("unable to save to database");
    });
});
Testing our code

Save your code. Go to your terminal and enter the command node app.js to start our server. Open up your browser and navigate to the URL “http://localhost:3000”. You will see our index.html file displayed to you.

Make sure you have mongo running.

Enter your first name and last name in the input fields and then click the “Add Name” button. You should get back text that says the name has been saved to the database like below.

Access to Code

The final version of the code is available in my Github repo. To access the code click here. Thank you for reading !