There is a requirement to Dockerize a Node app and to deploy the same on App Server 3. Under /node_app directory on App Server 3, we have already placed a package.json file that describes the app dependencies and server.js file that defines a web app framework.

  1. Create a Dockerfile (name is case sensitive) under /node_app directory:

    • Use any node image as the base image.
    • Install the dependencies using package.json file.
    • Use server.js in the CMD.
    • Expose port 8084.

  2. The build image should be named as nautilus/node-web-app.

  3. Now run a container named nodeapp_nautilus using this image.

    • Map the container port 8084 with the host port 8093.

. Once deployed, you can test the app using a curl command on App Server 3:

curl http://localhost:8093

Connect to App Server 3 

ssh banner@stapp03 sudo -i

Password for banner: BigGr33n

Inspect the Application Files 

cd /node_app ls -la

Output:

total 16 drwxr-xr-x 2 root root 4096 Oct 29 09:03 . dr-xr-xr-x 1 root root 4096 Oct 29 09:05 .. -rw-r--r-- 1 root root 332 Oct 29 09:03 package.json -rw-r--r-- 1 root root 296 Oct 29 09:03 server.js

View the dependency manifest:

cat /node_app/package.json

Output:

{ "name": "docker_web_app", "version": "1.0.0", "description": "Node.js on Docker", "author": "Sample Test <sample.test@example.com>", "main": "server.js", "keywords": [ "nodejs", "bootstrap", "express" ], "scripts": { "start": "node server.js" }, "dependencies": { "express": "^4.16.1" } }

View the application entry point:

cat /node_app/server.js

Output:

'use strict'; const express = require('express'); // Constants const PORT = 8084; const HOST = '0.0.0.0'; // App const app = express(); app.get('/', (req, res) => { res.send('Welcome to xFusionCorp Industries!'); }); app.listen(PORT, HOST); console.log(`Running on http://${HOST}:${PORT}`);

The app uses Express, listens on port 8084 at 0.0.0.0, and responds with a welcome message on the root route.

Create the Dockerfile 

vi /node_app/Dockerfile

Add the following content:

FROM node:18-alpine WORKDIR /node_app COPY package.json ./ RUN npm install COPY . . EXPOSE 8084 CMD ["node", "server.js"]

Verify the file:

cat /node_app/Dockerfile

Output:

FROM node:18-alpine WORKDIR /node_app COPY package.json ./ RUN npm install COPY . . EXPOSE 8084 CMD ["node", "server.js"]

Build the Image 

cd /node_app docker build -t nautilus/node-web-app .

Output:

[+] Building 15.0s (10/10) FINISHED docker:default => [internal] load build definition from Dockerfile 0.1s => => transferring dockerfile: 167B 0.0s => [internal] load metadata for docker.io/library/node:18-alpine 1.3s => [internal] load .dockerignore 0.1s => => transferring context: 2B 0.0s => [1/5] FROM docker.io/library/node:18-alpine@sha256:8d6421d663b4c28fd3ebc498332f249011d118 3.2s => [internal] load build context 0.1s => => transferring context: 878B 0.0s => [2/5] WORKDIR /node_app 0.1s => [3/5] COPY package.json ./ 0.3s => [4/5] RUN npm install 8.6s => [5/5] COPY . . 0.2s => exporting to image 0.9s => => exporting layers 0.8s => => writing image sha256:d413260175d707b6ac3e7f5b3d94bcb0edc8dab95c5243c93395f03c7f257268 0.0s => => naming to docker.io/nautilus/node-web-app 0.0s

The image built successfully in five steps: base image, working directory, dependency manifest copy, dependency install, and source copy.

Verify the Image 

docker images | grep nautilus

Output:

nautilus/node-web-app latest d413260175d7 3 seconds ago 135MB

The image nautilus/node-web-app:latest is available locally.

Run the Container 

docker run -d --name nodeapp_nautilus -p 8093:8084 nautilus/node-web-app

Output:

c464eceb6897346d4afce4b5437afe0d21f178c172b5fcf580bc193a90d64457

The container nodeapp_nautilus started in detached mode.

Verify the Port Mapping 

docker port nodeapp_nautilus

Output:

8084/tcp -> 0.0.0.0:8093 8084/tcp -> [::]:8093

Host port 8093 maps to container port 8084 on both IPv4 and IPv6.

Test the Application 

curl http://localhost:8093

Output:

Welcome to xFusionCorp Industries!

The application responds correctly, confirming the deployment is working.

Complete Command Sequence 

ssh banner@stapp03 sudo -i cd /node_app ls -la cat package.json cat server.js vi /node_app/Dockerfile # Add the Dockerfile content cat /node_app/Dockerfile docker build -t nautilus/node-web-app . docker images | grep nautilus docker run -d --name nodeapp_nautilus -p 8093:8084 nautilus/node-web-app docker port nodeapp_nautilus curl http://localhost:8093

Task Summary

Requirement Status
Dockerfile created at /node_app/Dockerfile Completed
Base image node:18-alpine used Completed
Dependencies installed from package.json Completed
server.js used in CMD Completed
Port 8084 exposed Completed
Image built as nautilus/node-web-app Completed
Container named nodeapp_nautilus running Completed
Host port 8093 mapped to container port 8084 Completed
App accessible via curl http://localhost:8093 Completed

Dockerfile Explanation

Line Description
FROM node:18-alpine Base image with Node.js 18 on Alpine Linux
WORKDIR /node_app Set working directory inside the image
COPY package.json ./ Copy dependency manifest first for layer caching
RUN npm install Install dependencies (express) from package.json
COPY . . Copy remaining application files, including server.js
EXPOSE 8084 Document the port the app listens on
CMD ["node", "server.js"] Start the application using server.js

Key Commands Reference

Command Purpose
docker build -t nautilus/node-web-app . Build the image from the Dockerfile
docker run -d --name nodeapp_nautilus -p 8093:8084 nautilus/node-web-app Run the container with port mapping
docker images List available images
docker port nodeapp_nautilus View port mapping
docker logs nodeapp_nautilus View container logs
curl http://localhost:8093 Test the Node app

Notes

  • The package.json is copied and npm install is run before copying the rest of the source for efficient layer caching
  • server.js is used as the entry point in CMD, and it listens on 0.0.0.0:8084
  • The container listens on port 8084 internally and is exposed on host port 8093
  • The container name nodeapp_nautilus and image name nautilus/node-web-app are used exactly as required
  • The application responds with Welcome to xFusionCorp Industries! on the root route
  • If the container exits immediately, check logs with docker logs nodeapp_nautilus to diagnose missing dependencies or startup errors