Build a Node.js environment with Docker

Introduction

What you are doing is almost the same as what is written in Node.js official page. Please note.

Rough procedure

1. Create a Node.js application
2. Creating a Dockerfile
3. Specify files to ignore when building Docker images
4. Build a Docker image
5. Start the Docker container
6. Access confirmation

Creating a Node.js application

First, create a node.js application locally.

Creating a working directory

Create a new directory for creating a Node.js application and move to it.

$mkdir directory name
$cd directory name

Create package.json

$ touch package.json

package.json

{
  "name": "docker_node_js",
  "version": "1.0.0",
  "description": "Node.js on Docker",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "express": "^4.16.1"
  }
}

--This time, we will use the Express.js framework.

Check npm version

$ npm --version

--Version 5 or later is recommended (because package-lock.json is created)

run npm install

$ npm install

--If npm version is 5 or later, package-lock.json will be created automatically after this execution. --The package is installed under the node_modules folder

Creating server.js

Create server.js in the directory where package.json is located

$ touch server.js

server.js

'use strict';

const express = require('express');

// Constants
const PORT = 8080;
const HOST = '0.0.0.0';

// App
const app = express();
app.get('/', (req, res) => {
  res.send('Hello World');
});

//Listen for connections on the specified port number
app.listen(PORT, HOST);

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

--See here for listening to connections.

Creating a Dockerfile

Create a Dockerfile in the directory where you created the js file in the above procedure.

Get the original image

Dockerfile

FROM node:lts

--This time, create an image based on the image of Node.js in Docker Hub --Select lts as the tag (** lts: long time support **) (See here for Laravel's lts)

Creating an application directory

Dockerfile

WORKDIR /usr/src/app

--Create a directory in the image to store the source code of this application. --It is recommended to use an absolute path (Reference)

Install the required libraries for your application

Dockerfile

COPY package*.json ./
RUN npm install

--Node.js and NPM are already installed in the image used this time, so install the necessary packages as the next step. --By using a wildcard (*), both package.json and package-lock.json should be copied. --By copying only the files required for npm install, you can use the cache when ** package * .json has not changed, so you can reduce the processing load ** (If you copy all the files, even if there is no change in package * .json, npm install will be executed just because any file in the working directory is changed, and the cache will be used effectively. Can not do it)

Copy the application source code into the image

Dockerfile

COPY . .

--After running the process npm install, copy (bundle) the contents of the working directory into the image.

Specify the port number to be exposed to the outside

Dockerfile

EXPOSE 8080

--The role is the same as specifying the -p option when executing the docker run command.

Execute the created js

Dockerfile

CMD [ "node", "server.js" ]

Contents of the finally completed Dockerfile

Dockerfile

FROM node:lts

WORKDIR /usr/src/app

COPY package*.json ./
RUN npm install

COPY . .

CMD [ "node", "server.js" ]

Specify files to ignore when building Docker image

In the .dockerignore file, specify the file to be ignored when building.

$ touch .dockerignore

.dockerignore

node_modules
npm-debug.log

--This description prevents locally installed modules and debug logs from being copied onto the Docker image or overwriting the image-like modules.

Build Docker image

Build the image based on the created Dockerfile.

$ docker build -t node_tutorial:latest .

--You can add a name and tag to the image by writing it in the format of -t: name: tag.

Check the created image

$ docker images node_tutorial:latest

Start Docker container

$ docker run -p 49160:8080 -d node_tutorial:latest

---p: Associate the port specified in server.js with the port of localhost ---d: Start in background

Check the running Docker image

$ docker ps 

Access confirmation

$ curl -i localhost:49160

HTTP/1.1 200 OK
X-Powered-By: Express
Content-Type: text/html; charset=utf-8
...

Hello, World!

---i: Output both Header and Body of Response

Check the log

$ docker logs node_container
Running on http://0.0.0.0:8080

Reference site

-Make Node.js Web Application Docker -Three points for improving lead time in Docker Build