Docker 101

Meet the portable future

Presented at PyOhio on 7/26/14

About me

Andrew T. Baker

Python consultant in Washington, DC

Django-district co-organizer

Spin-docker side project

@andrewtorkbaker

http://andrewtorkbaker.com

This presentation: https://slides.com/atbaker/docker-101/

Tutorial repo: https://github.com/atbaker/docker-tutorial

About you

Today

Short presentation covering docker basics
Self-paced tutorials
Informal, collaborative feel
Ask questions anytime!

What is docker?

LXC?

Virtualization tool?

Configuration manager?

VM manager?

Fancy cgroups?

Docker is something new

Docker.io says:

Docker is an open-source engine that automates the deployment of any application as a lightweight, portable, self-sufficient container that will run virtually anywhere.

App portability

Manual
configuration

Configuration
management tools

Traditional VMs

Docker

Environment agnostic

Environment specific

Source: docker.io

Typical docker architecture

Rule of thumb: One container for each process

Source: quay.io

Why is this a big deal?

It takes us one big step closer to
commoditization of computing services

Docker basics

Containers

Applications run in containers.

To create a container, you need a docker image and a command to execute:

$ docker run busybox /bin/echo foobar >> /tmp/foo.txthello world

Images

Saved states of containers.

To create an image, you commit changes you made in a container:

$ docker commit -m "Add foo.txt" e25605a6d745 atbaker/foobar

Dockerfiles (builder)

Scripts with a series of commands to build docker images:

# Spin-docker example dockerfile for a Django project

# Use phusion/baseimage as base image
FROM phusion/baseimage:0.9.8

MAINTAINER Andrew T. Baker <andrew@andrewtorkbaker.com># Add the Django app and install its requirements
ADD sd_sample_project /var/www/django
RUN apt-get install -y python-pip
RUN pip install virtualenv
RUN virtualenv /var/www/venv
RUN /.../venv/bin/pip install -r /.../requirements.txt...