Friday, October 13, 2017

Deploy nodeJs inside docker

Article Scope,

This article scope is limited to, Deploy existing node application inside docker container. this article does not discuss nodeJs and Docker, but I will briefly discuss what is nodeJ and Docker,

What is NodeJs,

You can find good documentation at  :

Node Documentation
W3School Node Tutorials
Tutorial point Node Tutorials

What is Docker,

You can find good documentation at :

Docker documentation

before jump in to the sample application  I would like to verify if you have installed node and docker in your local machine,

To verify node: open Powershell or Commad Propt ( I am in windows machine) if you are using Linux or Mac you can run below command in Terminal.

node -v : this command will print out current node version if you have install node correctly. if not please check your node installation in above guide line.

To verify Docker installation, run "docker" this will print out available option in docker, if you get error message , you need to check your installation

okay, here we go. Let's start sample node application. I am using Visual studio code, you can use your favorite editors like Atom, subline, webstorm etc..

This is a very simple node web app just shows hello world message inside Browser, I am using Express node module and you can use any http module like Http, hapiJs etc..  To initiate package json file just run below command  in powershell

create Directory name  "nodeInDocker" point terminal to that and run

npm init --yes

open up your editor and add new file called server.js, next install node dependency modules. In here we are using express module, to install latest express run command,

npm i express --save

This will pull the node module from npm site (registry) save on local directory inside node_module and update package json .

so we are good to start coding simple express web app, to do that insert below code to server.js

'use strict';

const express = require('express');
const PORT = 8080; //port for run web app
const HOST = '';
const app = express();

res.send('<h2>Hello world</h2>');

console.log(`Running on http://${HOST}: ${PORT}`);

To verify the code is working, run below command

node .\server.js :
This will print out  message "Running on 8080", open the browser and type address http://localhost:8080 if every thing is fine you, can see "Hello word" message in browser

So far, we did just create node express web app the main object is to run this application inside docker container. we will start that implementation. First add new file called "Dockerfile" do not specify any file extension. This contain all the information needed by docker to build docker image then place below content inside file.

FROM node
WORKDIR /usr/src/app
COPY package.json .
RUN npm install
COPY server.js .
CMD [ "npm","start" ]

Those are basic instructions which required by docker, 

1. FROM      : This specify what is a base image. so we used node image
2. WORDIR : Where to place deployment content inside the docker container
3. COPY       : Which one need to copy to above directory
4. RUN          : To run commands, in here it run npm install command which make sure install                                     required node modules
5. COPY        : Copy the server.js File which is our server app
6. EXPOSE  : Open port inside docker to access out side
7. CMD         : Final step to run command here start "node start "  will will run package.json "start                            script", in there we have mentions to run "node server.js"

"name": "nodeInDocker",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"test": "echo \"Error: no test specified\" && exit 1",
"start":"node server.js"
"author": "",
"license": "ISC",
"dependencies": {

To build image you need  base image called node which mention in Dockerfile "From" instructions set. so first, install that using docker pull command

docker pull node

This command pulls node image form docker hub. you can find that in

you can see installed images using 

docker images

We have every thing in hand now, to build docker image for our node app, run below command 

docker build -t nodeindocker:1.0 .

-t flag tag the image name and version number : nodeindocker 1.0

This will read Dockerfile and execute each command one by one. After successfully create that image, you can check newly created docker image using 

docker images

So now we have built new docker image which contains sample app and the dependency required to build sample web app, to run newly created docker container, run below command

docker run  -p 6161:8080 nodeindocker:1.0

-p flag specify host machine port forward to docker container so local machine port 6161 forward to nodeindocker:1.0 port 8080 (which is used sample web app to run)

Fire up the browser and type http://localhost/6161 you can see same message like previously we ran web app in localhost now it is running on inside docker.

you can see ruining docker containers using below command 

docker ps

to stop running docker container, run  command

docker stop <container id  or image name>

in my case it is

docker stop 80c2437fd8ed

Thank you very much reading this article , if you have any issue when creating this sample application please feel free contact me

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