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Rohith ND
Rohith ND

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How to use docker to run a node js application

#docker #node #javascript

In this blog, I'll show you how to build a node js application, generate an image for it, and run it using Docker.

Let's create our node js application.

mdkir nodejsapp cd nodejsapp
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Now lets initialize package.json file using the following command.

npm init
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Once your package.json file is created lets now install express.

npm install express
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Hence your package.json file looks like this.

{ "name": "nodejsapp", "version": "1.0.0", "description": "nodejsapp description", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1", "start": "node index.js" }, "author": "", "license": "ISC", "dependencies": { "express": "^4.17.3" } }
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Let's get started with index.js to build our website.

const express = require("express"); const app = express(); const port=3000; app.get("/", (req, res) => { res.sendFile(__dirname + "/index.html"); }) app.get("/page", (req, res) => { res.sendFile(__dirname + "/page.html"); }) app.listen(port, () => { console.log(`running at port ${port}`); });
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Let's make two files index.html and page.html

<!-- index.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Node JS</title> </head> <body> <h1>Node JS</h1> <p> Hello from Home </p> <br /> <a href="/page">next page</a> </body> </html>
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<!-- page.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Node JS Page</title> </head> <body> <h1>Second Page</h1> <p> Hello from page 2</p> <br /> <a href="/">Home page</a> </body> </html>
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In your root directory, create a Dockerfile and .dockerignore .

FROM node:14-alpine RUN mkdir -p /home/app COPY ./* /home/app/ EXPOSE 3000 WORKDIR /home/app RUN npm install CMD ["npm", "start"]
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node_modules/ package-lock.json
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To build the docker image run the following command

docker build -t nodeapp:latest . or docker build -t <dockerhub_name>/<app_name>:<tag> .
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To ensure that your Docker image has been built, open a terminal and type docker images.The output will be displayed as seen below.

REPOSITORY TAG IMAGE ID CREATED SIZE nodeapp latest e0a978b53566 8 seconds ago 123MB
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Let us now run our docker image named nodeapp (in my case).

docker run -p 3001:3000 e0a978b53566
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Because I have bound my application to port 3001, it runs on that port. You are free to modify it as you see fit.

docker run -p <PORT>:3000 <IMAGE ID>
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As a result, you can see your application running http://localhost:3001/ .

output1output2

I hope this blog is useful to you.

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