Containerization in Application Development – What is Containerization/Docker? – How can I use it?

What is Containerization/Docker?

Container vs. Virtualization

• Open Source
• Modern kernels > 3.10
• Old Redhat 2.6

Docker Container?

							
FROM ubuntu:12.04
RUN apt-get update && apt-get install -y python python-pip curl
RUN curl -sSL https://github.com/shykes/helloflask/archive/master.tar.gz | tar -xzv
RUN cd helloflask-master && pip install -r requirements.txt
						

But how does it work?

• OS Host kernel (https://superuser.com/questions/889472/docker-containers-have-their-own-kernel-or-not)
• http://www.slideshare.net/Docker/docker-lpc-2014cristian
• Dates back to year 2000
• FreeBSD jails
• Solaris Zones
• OpenVZ
• LXC (Linux Containers)

Why is it so popular?

• OpenSource
• Hardware- and platform-agnostic
• Flexibility (e.g. spin up whole integration testing environment on your notebook)
• Efficiency (four to six times the number of server application instances compared to Xen, KVM)

Why is it so popular?

• Perfect for immutable infrastructure
• Security (but not yet as good as BSD jails or real virtualization)
• Take control back over your processes

• http://www.zdnet.com/article/what-is-docker-and-why-is-it-so-darn-popular/
• a.k.a immutable servers, phoenix servers to avoid drift - differences between servers when they are supposed to be identical containers can share directories, network stack ...

The Docker Ecosystem

• Docker Hub
• Platform

How can I use it?

Dockerfile

							
FROM python:3.5

# copy SAP specific certs to make the SSL validation work
ADD certificates /usr/local/share/ca-certificates/
RUN update-ca-certificates

# create directory for app
RUN mkdir /app

# install required python 3.5 libs
COPY requirements.txt /app/
RUN pip3 --proxy proxy.wdf.sap.corp:8080 install -r /app/requirements.txt

# add handler for routes
ADD handler /app/handler

CMD python /app/app.py
EXPOSE 8080
							
						

The Base Image

$ sudo debootstrap raring raring > /dev/null
$ sudo tar -C raring -c . | docker import - raring
a29c15f1bf7a
$ docker run raring cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=13.04
DISTRIB_CODENAME=raring
DISTRIB_DESCRIPTION="Ubuntu 13.04"``
						

• All databases
• Runtime environments

Docker Compose

							
version: '2'
services:
  web:
    build: .
    ports:
     - "5000:5000"
    volumes:
     - .:/code
    depends_on:
     - redis
  redis:
    image: redis
							
						

Handling

The Terminal Interface

						
> $ docker pull tensorflow/tensorflow:latest
> $ docker run -p 8888:8888 -p 6006:6006 -it tensorflow/tensorflow:latest
						
					

Integraion into IDE