dockerizing web application

Walid Ashraf
Researcher , Software Developer, Instructor
about.me/WalidAshraf
DOCKERIZNG WEB
APPLICATIONS

Docker - Walid Ashraf
Table of Contents
Docker 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 basics
From:
• 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 basics
CMD
• 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
• TheVOLUME 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 Practices
Don’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

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<Mail@Mail.com>",
"dependencies": {
"express": "3.2.4"
}
}

Step 2: Create Index.JS File
var 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 history
Step 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 GitHub
The 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-app
cd docker-meetup/node-app
Build the image
docker build - t name/app-name .
run the container
docker run -d -p 1234:8080 name/app-name

The result

Create an application folder (flask-app)
CREATE A PYTHON
APPLICATION

Step 1: Create File app.py
from flask import Flask, render_template
import random
app = Flask(__name__)
# list of cat images
images = [
"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/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.txt
Flask==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 history
Step 5:
docker build -t washraf/flask-app .
Step 6:
docker run -p 8888:5000 -d --name flaskApplication washraf/flask-app

dockerizing web application

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