Senior DevOps Technical Writer
Node.js is an open-source JavaScript runtime environment for building server-side and networking applications. The platform runs on Linux, macOS, FreeBSD, and Windows. Though you can run Node.js applications at the command line, this tutorial will focus on running them as a service. This means that they will restart on reboot or failure and are safe for use in a production environment.
In this tutorial, you will set up a production-ready Node.js environment on a single Ubuntu 22.04 server. This server will run a Node.js application managed by PM2, and provide users with secure access to the application through an Nginx reverse proxy. The Nginx server will offer HTTPS using a free certificate provided by Let’s Encrypt.
This guide assumes that you have the following:
When you’ve completed the prerequisites, you will have a server serving your domain’s default placeholder page at https://example.com/
.
Let’s write a Hello World application that returns “Hello World” to any HTTP requests. This sample application will help you get up and running with Node.js. You can replace it with your own application — just make sure that you modify your application to listen on the appropriate IP addresses and ports.
First, using nano
or your favorite text editor, create a sample application called hello.js
:
- nano hello.js
Insert the following code into the file:
const http = require('http');
const hostname = 'localhost';
const port = 3000;
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello World!\n');
});
server.listen(port, hostname, () => {
console.log(`Server running at http://${hostname}:${port}/`);
});
Save the file and exit the editor. If you are using nano
, press Ctrl+X
, then when prompted, Y
and then Enter.
This Node.js application listens on the specified address (localhost
) and port (3000
), and returns “Hello World!” with a 200
HTTP success code. Since we’re listening on localhost
, remote clients won’t be able to connect to our application.
To test your application, type:
- node hello.js
You will receive the following output:
OutputServer running at http://localhost:3000/
Note: Running a Node.js application in this manner will block additional commands until the application is killed by pressing CTRL+C
.
To test the application, open another terminal session on your server, and connect to localhost
with curl
:
- curl http://localhost:3000
If you get the following output, the application is working properly and listening on the correct address and port:
OutputHello World!
If you do not get the expected output, make sure that your Node.js application is running and configured to listen on the proper address and port.
Once you’re sure it’s working, kill the application (if you haven’t already) by pressing CTRL+C
.
Next let’s install PM2, a process manager for Node.js applications. PM2 makes it possible to daemonize applications so that they will run in the background as a service.
Use npm
to install the latest version of PM2 on your server:
- sudo npm install pm2@latest -g
The -g
option tells npm
to install the module globally, so that it’s available system-wide.
Let’s first use the pm2 start
command to run your application, hello.js
, in the background:
- pm2 start hello.js
This also adds your application to PM2’s process list, which is outputted every time you start an application:
Output...
[PM2] Spawning PM2 daemon with pm2_home=/home/sammy/.pm2
[PM2] PM2 Successfully daemonized
[PM2] Starting /home/sammy/hello.js in fork_mode (1 instance)
[PM2] Done.
┌────┬────────────────────┬──────────┬──────┬───────────┬──────────┬──────────┐
│ id │ name │ mode │ ↺ │ status │ cpu │ memory │
├────┼────────────────────┼──────────┼──────┼───────────┼──────────┼──────────┤
│ 0 │ hello │ fork │ 0 │ online │ 0% │ 25.2mb │
└────┴────────────────────┴──────────┴──────┴───────────┴──────────┴──────────┘
As indicated above, PM2 automatically assigns an App name
(based on the filename, without the .js
extension) and a PM2 id
. PM2 also maintains other information, such as the PID
of the process, its current status, and memory usage.
Applications that are running under PM2 will be restarted automatically if the application crashes or is killed, but we can take an additional step to get the application to launch on system startup using the startup
subcommand. This subcommand generates and configures a startup script to launch PM2 and its managed processes on server boots:
- pm2 startup systemd
The last line of the resulting output will include a command to run with superuser privileges in order to set PM2 to start on boot:
Output[PM2] Init System found: systemd
sammy
[PM2] To setup the Startup Script, copy/paste the following command:
sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u sammy --hp /home/sammy
Run the command from the output, with your username in place of sammy
:
- sudo env PATH=$PATH:/usr/bin /usr/lib/node_modules/pm2/bin/pm2 startup systemd -u sammy --hp /home/sammy
As an additional step, we can save the PM2 process list and corresponding environments:
- pm2 save
You have now created a systemd unit that runs pm2
for your user on boot. This pm2
instance, in turn, runs hello.js
.
Start the service with systemctl
:
- sudo systemctl start pm2-sammy
Check the status of the systemd unit:
- systemctl status pm2-sammy
For a detailed overview of systemd, please review Systemd Essentials: Working with Services, Units, and the Journal.
In addition to those we have covered, PM2 provides many subcommands that allow you to manage or look up information about your applications.
Stop an application with this command (specify the PM2 App name
or id
):
- pm2 stop app_name_or_id
Restart an application:
- pm2 restart app_name_or_id
List the applications currently managed by PM2:
- pm2 list
Get information about a specific application using its App name
:
- pm2 info app_name
The PM2 process monitor can be pulled up with the monit
subcommand. This displays the application status, CPU, and memory usage:
- pm2 monit
Note that running pm2
without any arguments will also display a help page with example usage.
Now that your Node.js application is running and managed by PM2, let’s set up the reverse proxy.
Your application is running and listening on localhost
, but you need to set up a way for your users to access it. We will set up the Nginx web server as a reverse proxy for this purpose.
In the prerequisite tutorial, you set up your Nginx configuration in the /etc/nginx/sites-available/example.com
file. Open this file for editing:
- sudo nano /etc/nginx/sites-available/example.com
Within the server
block, you should have an existing location /
block. Replace the contents of that block with the following configuration. If your application is set to listen on a different port, update the highlighted portion to the correct port number:
server {
...
location / {
proxy_pass http://localhost:3000;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection 'upgrade';
proxy_set_header Host $host;
proxy_cache_bypass $http_upgrade;
}
...
}
This configures the server to respond to requests at its root. Assuming our server is available at example.com
, accessing https://example.com/
via a web browser would send the request to hello.js
, listening on port 3000
at localhost
.
You can add additional location
blocks to the same server block to provide access to other applications on the same server. For example, if you were also running another Node.js application on port 3001
, you could add this location block to allow access to it via https://example.com/app2
:
server {
...
location /app2 {
proxy_pass http://localhost:3001;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection 'upgrade';
proxy_set_header Host $host;
proxy_cache_bypass $http_upgrade;
}
...
}
Once you are done adding the location blocks for your applications, save the file and exit your editor.
Make sure you didn’t introduce any syntax errors by typing:
- sudo nginx -t
Restart Nginx:
- sudo systemctl restart nginx
Assuming that your Node.js application is running, and your application and Nginx configurations are correct, you should now be able to access your application via the Nginx reverse proxy. Try it out by accessing your server’s URL (its public IP address or domain name).
Congratulations! You now have your Node.js application running behind an Nginx reverse proxy on an Ubuntu 22.04 server. This reverse proxy setup is flexible enough to provide your users access to other applications or static web content that you want to share.
Next, you may want to look into How to build a Node.js application with Docker.
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Hello, I’ve follow this tutorial, thanks, but I have an issue I try to resolve for 48h without success : I use react, so I changed res.end by the res.sendFile(“index.html”) of express (I did the express.static and all stuff) When I go to the website url, I have the index.html page but… every url is 404 (app.js, app.css…)
I am desperate. Please, can you help me ?
After setting up the reverse proxy to
http://localhost:1337
is anyone getting a 502 Bad Gateway? I checked the logs/var/log/nginx/error.log
and getting:Closest thing I’ve found to an answer online is here, but it still doesn’t seem to work.
I would also add this to proxy config to pass-on visitors real-IP:
Thanks for the amazing tutorials. These are super helpful and guide in the right direction. I would suggest mentioning that user might have to restart VM before running
sudo systemctl start pm2-sammy
command. I faced a similar issue as mentioned in https://github.com/Unitech/pm2/issues/3924 and restarting resolved the problem.