Deploying a Node.js application on an EC2 instance and configuring a domain to point to it while ensuring the app keeps running involves several steps. Here's a comprehensive guide to achieve this:

Prerequisites

1. AWS Account
2. Domain name
3. Basic knowledge of Node.js, SSH, and Linux command line

Steps

1. Launch an EC2 Instance
   • Log in to your AWS Management Console.
   • Navigate to the EC2 Dashboard.
   • Click "Launch Instance".
   • Choose an Amazon Machine Image (AMI), preferably Ubuntu or Amazon Linux.
   • Choose an instance type (e.g., t2.micro for small applications).
   • Configure instance details, storage, and tags as needed.
   • Configure Security Group to allow HTTP (port 80), HTTPS (port 443), and SSH (port 22) access.
   • Review and launch the instance, then download the key pair for SSH access.

2. Set Up the EC2 Instance

   • Connect to your EC2 instance via SSH:
     

     ssh -i /path/to/your-key-pair.pem ubuntu@your-ec2-public-ip
     
     

- Update the package list and install the necessary dependencies:

    ```
    sudo apt update
    sudo apt install nodejs npm
    sudo npm install -g pm2

    ```

1. Deploy Your Node.js Application

   • Transfer your application code to the EC2 instance using scp or by cloning from a Git repository:
     

     scp -i /path/to/your-key-pair.pem -r /local/path/to/your-app ubuntu@your-ec2-public-ip:/home/ubuntu
     
     

- Navigate to your application directory and install dependencies:

    ```
    cd /home/ubuntu/your-app
    npm install

    ```

- Start your Node.js application using PM2 to keep it running:

    ```
    pm2 start app.js
    pm2 save
    pm2 startup

    ```

1. Set Up a Domain Name
   • Go to your domain registrar and configure the DNS settings:
     • Create an A record pointing to your EC2 instance's public IP address.
   • (Optional) For SSL, consider using AWS Certificate Manager and setting up an Application Load Balancer (ALB).

2. Configure a Reverse Proxy with Nginx (Optional but Recommended)

   • Install Nginx:
     

     sudo apt install nginx
     
     

- Configure Nginx as a reverse proxy:

    ```
    sudo nano /etc/nginx/sites-available/default

    ```

    - Replace the contents with the following (adjust paths and server name as needed):

        ```
        server {
            listen 80;
            server_name your-domain.com;

            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;
            }
        }

        ```

- Test the Nginx configuration and restart Nginx:

    ```
    sudo nginx -t
    sudo systemctl restart nginx

    ```

1. Access Your Application
   • Navigate to your domain in a web browser to see your deployed Node.js application.

Additional Tips

• Security: Regularly update your EC2 instance and installed packages.
• Monitoring: Use PM2's monitoring tools to keep track of your application's performance.
• Backups: Consider setting up automatic backups of your EC2 instance and application data.

This guide provides a basic setup. For production environments, you may want to look into more advanced configurations, such as load balancing, auto-scaling, and using a managed database service like Amazon RDS.