Deploy Node API and reverse proxy

Configuring Nginx as a Reverse Proxy

1. Create a small express app

Install nodejs and npm on ubuntu

sudo apt install nodejs
sudo apt install npm

Create a project dir and initialize a node app
Terminal window
```
mkdir express-app
cd express-app
npm init -y
```
Install basic dependencies
Terminal window
```
npm install express nodemon
```

Update the package.json

{
  "name": "express-app",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "dev": "nodemon index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "express": "^4.19.2",
    "nodemon": "^3.1.4"
  }
}

Create an `index.js1 file and add the following code

touch index.js

import express from "express";

const app = express();

app.get("/api", (req, res) => {
  return res.status(200).json({
    message: "server working",
  });
});

app.listen(8080, () => console.log("Server is running on 8080"));

Install pm2 to run this dummy app in the background

npm install -g pm2 # if npm is not available use sudo npm install -g pm2

Run the application with the following command:
Terminal window
```
pm2 start "npm run dev"
```

This will start the application on port 8080.

2. Do a reverse proxy with nginx

Nginx can also act as a reverse proxy, forwarding client requests to other servers.

Edit your server block configuration:
Terminal window
```
sudo vim /etc/nginx/sites-available/default
```

Configure the server block to act as a reverse proxy:

server {
 listen 80;  # Listen on port 80 for incoming HTTP requests
 server_name localhost;  # Server name or domain name this block will respond to

 location / {
     proxy_pass http://127.0.0.1:8080;  # Proxy requests to the backend server running on localhost:8080
     proxy_set_header Host $host;  # Set the Host header to the client's original host
     proxy_set_header X-Real-IP $remote_addr;  # Set the X-Real-IP header to the client's IP address
     proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;  # Append client's IP addresses to X-Forwarded-For header
     proxy_set_header X-Forwarded-Proto $scheme;  # Set the X-Forwarded-Proto header to the client's protocol (http or https)
 }
}

Test and reload Nginx:

sudo nginx -t
sudo systemctl reload nginx

Now, when you request http://<server_ip>/api it will return the following response:

{ "message": "server working" }