How to Setup a Koa.js Node Application on Ubuntu 20.04 with Nginx

Overview

Koa.js is a modern web framework built on Node.js. It allows developers to build high-performace and scalable web applications by focusing on a concise and extendible API built on asynchronous functionality in Node.js.

Prerequisites

Deploy a new Ubuntu 20.04 Vultr cloud server.
Set up a non-root user with sudo privileges.
Verify your server is up to date.

Install Nodejs & Yarn

Koa requires Node.js version v7.6.0 or higher.

Install the latest LTS version of Nodejs.

$ curl -fsSL https://deb.nodesource.com/setup_lts.x | sudo -E bash -

$ sudo apt-get install nodejs

Verify successful Nodejs installation.
```
$ node -v

v16.xx.x
```

Install Yarn.

$ curl -fsSL https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -

$ echo "deb https://dl.yarnpkg.com/debian/ stable main" | sudo tee /etc/apt/sources.list.d/yarn.list

$ sudo apt-get update && sudo apt-get install yarn

Verify successful Yarn installation.
```
$ yarn -v

1.2x.xx
```

Setup Application

Create the project root directory.

$ cd ~

$ mkdir koaserver && cd koaserver

Initialize the Node.js project environment through yarn and answer the question prompts according to your project.
```
$ yarn init
```
Install Koa.
```
$ yarn add koa
```
Create index.js.
```
$ touch index.js
```

Add sample code to index.js.

const Koa = require("koa");

const app = new Koa();



app.use(async (ctx) => {

        ctx.body = "Hello World";

})



app.listen(3000);

Setup PM2

PM2 will manage the Node.js application to run in the background as a system process. PM2 will automatically restart the server if it crashes, handle logs, and monitor performance.

Install PM2.
```
$ sudo yarn global add pm2
```
Confirm successful installation.
```
$ pm2 -V

5.x.x
```
Navigate to the project folder and start the Koa server through PM2.
```
$ cd ~/koaserver

$ pm2 start index.js --name koaserver
```
Set PM2 to run on startup.
```
$ eval "$(pm2 startup | tail -1)"
```
Save PM2 configuration.
```
$ pm2 save
```

Setup Reverse Proxy through Nginx

Install Nginx.
```
$ sudo apt-get install nginx
```

Delete default Nginx server block.

$ sudo rm /etc/nginx/sites-enabled/default

Create a new Nginx server block.

$ sudo touch /etc/nginx/sites-enabled/koaserver.conf

Add the following text to the file.

server {

    listen 80;

    listen [::]:80;



    server_name _;



    location / {

        proxy_pass http://127.0.0.1:3000;

    }

}

Restart Nginx.
```
$ sudo systemctl nginx restart
```
Verify a working server response by navigating to your server's IP address in a browser. You should see a Hello World message.

Setup Firewall

For added security, configure a firewall to restrict access to internal service ports.

Setup UFW rules.
```
$ sudo ufw allow 22,80,443/tcp
```

Add any other ports according to your application and needs.

Enable UFW.
```
$ sudo ufw enable
```
Verify UFW working.
```
$ sudo ufw status

Status: active
```

Conclusion

For more information, refer to the official Koa.js documentation.

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