Add Node.js on Docker guide

locale/en/docs/guides/nodejs-docker-webapp.md

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+---
+title: Dockerizing a Node.js web app
+layout: docs.hbs
+---
+
+# Dockerizing a Node.js web app
+
+The goal of this example is to show you how to get a Node.js application into a
+Docker container. It assumes you have a working [Docker
+installation](https://docs.docker.com/engine/installation/) and a basic
+understanding of how a Node.js application is structured.
+
+In the first part of this guide we will create a simple web application in
+Node.js, then we will build a Docker image for that application, and lastly we
+will run the image as container.
+
+Docker allows you to package an application with all of its dependencies into a
+standardized unit, called a container, for software development. A container is
+a stripped-to-basics version of a Linux operating system. An image is software
+you load into a container.
+
+## Create the Node.js app
+
+First, create a new directory where all the files would live. In this directory
+create a `package.json` file that describes your app and its dependencies:
+
+```javascript
+{
+  "name": "docker_web_app",
+  "version": "1.0.0",
+  "description": "Node.js on Docker",
+  "author": "First Last <first.last@example.com>",
+  "main": "index.js",
+  "dependencies": {
+    "express": "^4.13.3"
+  }
+}
+```
+
+Then, create an `index.js` file that defines a web app using the
+[Express.js](http://expressjs.com/) framework:
+
+```javascript
+'use strict';
+
+const express = require('express');
+
+// Constants
+const PORT = 8080;
+
+// App
+const app = express();
+app.get('/', function (req, res) {
+  res.send('Hello world\n');
+});
+
+app.listen(PORT);
+console.log('Running on http://localhost:' + PORT);
+```
+
+In the next steps, we'll look at how you can run this app inside a Docker
+container using the official Docker image. First, you'll need to build a Docker
+image of your app.
+
+## Creating a Dockerfile
+
+Create an empty file called `Dockerfile`:
+
+```markup
+touch Dockerfile
+```
+
+Open the `Dockerfile` in your favorite text editor
+
+The first thing we need to do is define from what image we want to build from.
+Here we will use the latest LTS (long term support) version `argon` of `node`
+available from the [Docker Hub](https://hub.docker.com/):
+
+```docker
+FROM node:argon
+```
+
+Next we create a directory to hold the application code inside the image, this
+will be the working directory for your application:
+
+```docker
+# Create app directory
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+```
+
+This image comes with Node.js and NPM already installed so the next thing we
+need to do is to install your app dependencies using the `npm` binary:
+
+```docker
+# Install app dependencies
+COPY package.json /usr/src/app/
+RUN npm install
+```
+
+To bundle your app's source code inside the Docker image, use the `COPY`
+instruction:
+
+```docker
+# Bundle app source
+COPY . /usr/src/app
+```
+
+Your app binds to port `8080` so you'll use the `EXPOSE` instruction to have it
+mapped by the `docker` daemon:
+
+```docker
+EXPOSE 8080
+```
+
+Last but not least, define the command to run your app using `CMD` which defines
+your runtime. Here we will use the basic `npm start` which will start the `main`
+file defined in your `package.json`:
+
+```docker
+CMD [ "npm", "start" ]
+```
+
+Your `Dockerfile` should now look like this:
+
+```docker
+FROM node:argon
+
+# Create app directory
+RUN mkdir -p /usr/src/app
+WORKDIR /usr/src/app
+
+# Install app dependencies
+COPY package.json /usr/src/app/
+RUN npm install
+
+# Bundle app source
+COPY . /usr/src/app
+
+EXPOSE 8080
+CMD [ "npm", "start" ]
+```
+
+## Building your image
+
+Go to the directory that has your `Dockerfile` and run the following command to
+build the Docker image. The `-t` flag lets you tag your image so it's easier to
+find later using the `docker images` command:
+
+```bash
+$ docker build -t <your username>/node-web-app .
+```
+
+Your image will now be listed by Docker:
+
+```bash
+$ docker images
+
+# Example
+REPOSITORY                      TAG        ID              CREATED
+node                            argon      539c0211cd76    3 weeks ago
+<your username>/node-web-app    latest     d64d3505b0d2    1 minute ago
+```
+
+## Run the image
+
+Running your image with `-d` runs the container in detached mode, leaving the
+container running in the background. The `-p` flag redirects a public port to a
+private port inside the container. Run the image you previously built:
+
+```bash
+$ docker run -p 49160:8080 -d <your username>/node-web-app
+```
+
+Print the output of your app:
+
+```bash
+# Get container ID
+$ docker ps
+
+# Print app output
+$ docker logs <container id>
+
+# Example
+Running on http://localhost:8080
+```
+
+If you need to go inside the container you can use the `exec` command:
+
+```bash
+# Enter the container
+$ docker exec -it <container id> /bin/bash
+```
+
+## Test
+
+To test your app, get the port of your app that Docker mapped:
+
+```bash
+$ docker ps
+
+# Example
+ID            IMAGE                                COMMAND    ...   PORTS
+ecce33b30ebf  <your username>/node-web-app:latest  npm start  ...   49160->8080
+```
+
+In the example above, Docker mapped the `8080` port inside of the container to
+the port `49160` on your machine.
+
+Now you can call your app using `curl` (install if needed via: `sudo apt-get
+install curl`):
+
+```bash
+$ curl -i localhost:49160
+
+HTTP/1.1 200 OK
+X-Powered-By: Express
+Content-Type: text/html; charset=utf-8
+Content-Length: 12
+Date: Sun, 02 Jun 2013 03:53:22 GMT
+Connection: keep-alive
+
+Hello world
+```
+
+We hope this tutorial helped you get up and running a simple Node.js application
+on Docker.
+
+You can find more information about Docker and Node.js on Docker in the
+following places:
+
+* [Official Node.js Docker Image](https://registry.hub.docker.com/_/node/)
+* [Official Docker documentation](https://docs.docker.com/)
+* [Docker Tag on StackOverflow](http://stackoverflow.com/questions/tagged/docker)
+* [Docker Subreddit](https://reddit.com/r/docker)