How to Deploy Multiple Node.js Applications on a Single DigitalOcean Droplet with PM2 and Nginx

How to Host Multiple Node.js Applications on a DigitalOcean Droplet

Hosting multiple Node.js applications on a single DigitalOcean droplet is a cost-effective way to manage your projects. In this guide, I'll show you how to host three backend servers, each running on different ports (5000, 5001, and 5002), using tools like NVM, PM2, and Nginx.

1. Access Your Droplet

To start, you'll need to SSH into your DigitalOcean droplet. This is done by using the ssh command with your droplet’s IP address and root password.

ssh root@<ip>
<password>

2. Update Your System

Once logged in, it’s a good practice to update your system to ensure all packages are up-to-date.

apt update
apt upgrade -y

3. Install Node.js and npm Using NVM

Node Version Manager (NVM) is a great tool for managing multiple Node.js versions. Let’s install NVM and use it to set up Node.js.

1. Install NVM:

   curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.3/install.sh | bash
   source ~/.bashrc

1. Verify the Installation and List Available Node.js Versions:

   nvm help
   nvm list-remote

1. Install the Required Node.js Version:

   nvm install v20.10.0

1. Set the Node.js Version to Use:

   nvm use v20.10.0

1. Check the Installed Version:

   nvm current

With Node.js installed, npm is also automatically available.

4. Clone Your Projects

Now that Node.js is ready, clone each of your backend projects to the droplet.

Application 1 (Port 5000)

git clone https://github.com/your_username/app1_repository.git
cd app1_repository
npm install

Application 2 (Port 5001)

git clone https://github.com/your_username/app2_repository.git
cd app2_repository
npm install

Application 3 (Port 5002)

git clone https://github.com/your_username/app3_repository.git
cd app3_repository
npm install

5. Set Up PM2

PM2 is a process manager for Node.js applications. It allows your application to run in the background and will automatically restart it if it crashes.

Start Application 1 on Port 5000

pm2 start /path/to/app1/app.js --name "app1" --watch -- --port 5000

Start Application 2 on Port 5001

pm2 start /path/to/app2/app.js --name "app2" --watch -- --port 5001

Start Application 3 on Port 5002

pm2 start /path/to/app3/app.js --name "app3" --watch -- --port 5002

PM2 ensures each app remains running even if the terminal session ends, and the --watch flag will monitor your files for changes.

6. Set Up Nginx

Nginx will serve as a reverse proxy to route incoming HTTP requests to your Node.js applications.

1. Install Nginx:

   apt install nginx -y

1. Create Nginx Configuration Files for Each App:

Configuration for Application 1

nano /etc/nginx/sites-available/app1

Add the following configuration:

server {
    listen 80;
    server_name app1.your_domain_or_ip;

    location / {
        proxy_pass http://localhost:5000;
        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;
    }
}

Configuration for Application 2

nano /etc/nginx/sites-available/app2

Add the following configuration:

server {
    listen 80;
    server_name app2.your_domain_or_ip;

    location / {
        proxy_pass http://localhost:5001;
        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;
    }
}

Configuration for Application 3

nano /etc/nginx/sites-available/app3

Add the following configuration:

server {
    listen 80;
    server_name app3.your_domain_or_ip;

    location / {
        proxy_pass http://localhost:5002;
        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;
    }
}

1. Enable the Configurations:

Create symbolic links for each configuration file to enable them.

ln -s /etc/nginx/sites-available/app1 /etc/nginx/sites-enabled/
ln -s /etc/nginx/sites-available/app2 /etc/nginx/sites-enabled/
ln -s /etc/nginx/sites-available/app3 /etc/nginx/sites-enabled/

1. Test the Configuration:

nginx -t

1. Restart Nginx:

systemctl restart nginx

7. Adjust the Firewall

Ensure your firewall allows traffic through Nginx.

ufw allow 'Nginx Full'

8. Access Your APIs

Each API should now be accessible via your domain name or IP address.

• Application 1: http://app1.your_domain_or_ip
• Application 2: http://app2.your_domain_or_ip
• Application 3: http://app3.your_domain_or_ip

9. Set Up SSL with Let's Encrypt

Finally, secure your APIs with SSL using Let's Encrypt.

1. Install Certbot:

   apt install certbot python3-certbot-nginx -y

1. Obtain SSL Certificates for Each Application:

SSL for Application 1

certbot --nginx -d app1.your_domain_or_ip

SSL for Application 2

certbot --nginx -d app2.your_domain_or_ip

SSL for Application 3

certbot --nginx -d app3.your_domain_or_ip

Follow the prompts to complete the SSL setup. Afterward, your APIs will be accessible via HTTPS.

• Application 1: https://app1.your_domain_or_ip
• Application 2: https://app2.your_domain_or_ip
• Application 3: https://app3.your_domain_or_ip

Conclusion

Congratulations! You've successfully hosted multiple Node.js applications on a single DigitalOcean droplet. With PM2 managing your applications and Nginx handling incoming requests, your server is now robust and capable of running multiple apps simultaneously.

Happy coding!