Prerequisites
This guide assumes that you have the following:
An Ubuntu 22.04 server setup, as described in the initial server setup guide for Ubuntu 22.04. You should have a non-root user with sudo privileges and an active firewall. A domain name pointed at your server’s public IP. This tutorial will use the domain name example.com throughout. Nginx installed, as covered in How To Install Nginx on Ubuntu 22.04. Nginx configured with SSL using Let’s Encrypt certificates. How To Secure Nginx with Let’s Encrypt on Ubuntu 22.04 will walk you through the process. Node.js installed on your server. How To Install Node.js on Ubuntu 22.04 When you’ve completed the prerequisites, you will have a server serving your domain’s default placeholder page at https://example.com/.
Step 1 — Creating a Node.js Application
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:
Insert the following code into the file:
~/hello.js
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:
You will receive the following output:
Output
Server 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:
If you get the following output, the application is working properly and listening on the correct address and port:
Output
Hello 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.
Step 2 — Installing PM2
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:
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:
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:
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:
As an additional step, we can save the PM2 process list and corresponding environments:
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:
Check the status of the systemd unit:
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):
Restart an application:
List the applications currently managed by PM2:
Get information about a specific application using its App name:
The PM2 process monitor can be pulled up with the monit subcommand. This displays the application status, CPU, and memory usage:
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.
Step 3 — Setting Up Nginx as a Reverse Proxy Server
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:
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:
/etc/nginx/sites-available/example.com
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:
/etc/nginx/sites-available/example.com — Optional
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:
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).
Conclusion
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.