dockerizing web application

Walid AshrafResearcher , Software Developer, Instructor

about.me/WalidAshraf

DOCKERIZNG WEB APPLICATIONS

Docker - Walid Ashraf

Table of ContentsDocker File Basics

Creating a NodeJS application

Creating a python application

Docker file acts as the source code for your

image where you specify all the needed tools,

data, code to run you image correctly in any

environment.

DOCKER FILE BASICS


Docker file basicsFrom:

• Base Image

• Usage

• FROM <image>

Maintainer

• Who is the Image creator

• Usage

• MAINTAINER <Name>

WORKDIR

• Sets the start directory for the container where the run and the CMD instructions are executed.

• Usage

• WORKDIR /path/to/workdir

RUN

• The RUN instruction will execute any commands in a new layer on top of the current image and commit the results. The resulting committed image will be used for the next step in the Dockerfile.

• Usage

• RUN <command> (the command is run in a shell - /bin/sh -c - shell form)

• RUN ["executable", "param1", "param2"] (exec form)


Docker file basicsCMD

• The CMD Command is used as a default entry point to container. And if more than one is added the last one only will take effect

• Usage

• CMD ["executable","param1","param2"] (exec form, this is the preferred form)

• CMD ["param1","param2"] (as default parameters to ENTRYPOINT)

• CMD command param1 param2 (shell form)

COPY

• Copies files from the host file system to the image file system.

• Usage

• COPY <src>... <dest>

• COPY ["<src>",... "<dest>"] (this form is required for paths containing whitespace)

ADD

• The add file is similar to the copy but can handle both tar files and remote URLs

• Usage

• ADD <src>... <dest>

• ADD ["<src>",... "<dest>"] (this form is required for paths containing whitespace)

ENV

• Sets some environment variables for the container

• Usage

• ENV <key> <value> only one perline

• ENV <key>=<value> ... allows multiple per line


Docker file basics

EXPOSE

• This allows the container ports to be accessed from the global ports. Note that Port mapping has to be specified directly at creation time using the –p or –P commands

• Usage

• EXPOSE <port> [<port>...]

Vloume

• The VOLUME instruction creates a mount point with the specified name and marks it as holding externally mounted volumes from native host or other containers.

• Usage

• VOLUME ["/data"]


Docker File Best PracticesDon’t add unnecessary files or libraries

Utilize the ecosystem and don't reinvent images

For more ideas and best practices check:

https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/

http://www.walidashraf.com/2015/10/docker-and-solid-princple.html

https://docs.docker.com/engine/userguide/eng-image/dockerfile_best-practices/

http://www.walidashraf.com/2015/10/docker-and-solid-princple.html

Create an application folder (node-app)

CREATING NODEJS

APPLICATION


Step 1: Create package.json file{

"name": "docker-ubuntu-hello",

"private": true,

"version": "0.0.1",

"description": "Node.js Hello world app using docker",

"author": "Yourname<[email protected]>",

"dependencies": {

"express": "3.2.4"

}

}


Step 2: Create Index.JS Filevar express = require('express');

// Constants

var PORT = 8080;

// App

var app = express();

app.get('/', function (req, res) {

res.send('Hello Docker Cairo Geeks :D \n');

});

app.listen(PORT);

console.log('Running on http://localhost:' + PORT);


Step 3: Create A DockerFile# Aminimal alpine node image

FROM mhart/alpine-node

# Get The Code

COPY . /src

# Install app dependencies

RUN cd /src; npm install

#Expose a port

EXPOSE 8080

#The Container Start command

CMD ["node", "/src/index.js"]


& the rest is historyStep 4: Build The Image from Docker File

$ sudo docker build -t washraf/nodeapp .

Step 5: Run the Docker Image

$ sudo docker run -p 1234:8080 –d --name nodeApplication washraf/nodeapp


Other: Install form GitHubThe Repo:

https://github.com/washraf/docker-meetup

Install git:apt-get install git

Get the Code:git clone https://github.com/washraf/docker-meetup

Go to node-appcd docker-meetup/node-app

Build the imagedocker build - t name/app-name .

run the containerdocker run -d -p 1234:8080 name/app-name

https://github.com/washraf/docker-meetup


The result

Create an application folder (flask-app)

CREATE A PYTHON

APPLICATION


Step 1: Create File app.pyfrom flask import Flask, render_templateimport randomapp = Flask(__name__)# list of cat imagesimages = [

"http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26388-1381844103-11.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr01/15/9/anigif_enhanced-buzz-31540-1381844535-8.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26390-1381844163-18.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-1376-1381846217-0.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3391-1381844336-26.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/10/anigif_enhanced-buzz-29111-1381845968-0.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/9/anigif_enhanced-buzz-3409-1381844582-13.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr02/15/9/anigif_enhanced-buzz-19667-1381844937-10.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr05/15/9/anigif_enhanced-buzz-26358-1381845043-13.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-18774-1381844645-6.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr06/15/9/anigif_enhanced-buzz-25158-1381844793-0.gif","http://ak-hdl.buzzfed.com/static/2013-10/enhanced/webdr03/15/10/anigif_enhanced-buzz-11980-1381846269-1.gif"

]@app.route('/')def index():

url = random.choice(images)return render_template('index.html', url=url)

if __name__ == "__main__":app.run(host="0.0.0.0")


Step 2: Create requirements.txtFlask==0.10.1


Step 3: Create templates/index.html<html><head>

<style type="text/css">body {background: black; color: white;

}div.container { max-width: 500px; margin: 100px auto; border: 20px solid white; padding: 10px; text-align: center; }h4 {text-transform: uppercase;

}</style>

</head><body>

<div class="container"><h4>Cat Gif of the day</h4><img src="{{url}}" /><p>

<small>Courtesy: <a href="http://www.buzzfeed.com/copyranter/the-best-cat-gif-post-in-the-history-of-cat-gifs">Buzzfeed</a></small></p></div>

</body></html>


Step 4: Create Docker file# our base image

FROM alpine:latest

# Install python and pip

RUN apk add --update py-pip

# install Python modules needed by the Python app

COPY requirements.txt /usr/src/app/

RUN pip install --no-cache-dir -r /usr/src/app/requirements.txt

# copy files required for the app to run

COPY app.py /usr/src/app/

COPY templates/index.html /usr/src/app/templates/

# tell the port number the container should expose

EXPOSE 5000

# run the application

CMD ["python", "/usr/src/app/app.py"]


& the rest is historyStep 5:

docker build -t washraf/flask-app .

Step 6:

docker run -p 8888:5000 -d --name flaskApplication washraf/flask-app


The result

Docker - Walid Ashraf22

dockerizing web application

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