Virtualization tool?

Docker.com says

Docker is an open platform for developers and sysadmins to build, ship, and run distributed applications.

Docker Engine

A portable, lightweight runtime and packaging tool

Docker Hub

A cloud service for sharing applications and automating workflows

Less portable, minimal overhead

Most portable,
lots of overhead

Manual
configuration

Traditional VMs

CM tools

This is what makes Docker so powerful

Containers

Applications run in containers

$ docker run busybox /bin/echo "hello world"
hello world

docker run [OPTIONS] IMAGE [COMMAND] [ARG...]

Images

Saved states of containers. 

$ docker history atbaker/sd-django
IMAGE               CREATED             CREATED BY                                      SIZE
2c69173d3c3e        6 months ago        /bin/sh -c apt-get clean && rm -rf /var/lib/a   7 B
cf07ee82aaa6        6 months ago        /bin/sh -c chown root /opt/sd_client.py /var/   1.162 kB
4a3046bdcd25        6 months ago        /bin/sh -c #(nop) ADD file:0854b61af5a8f7051c   259 B
519ac326d2de        6 months ago        /bin/sh -c #(nop) ADD file:03065d55ff7e64caa9   896 B
5f87ccb7c84f        6 months ago        /bin/sh -c chown root /etc/service/gunicorn/r   871 B
aa069b102781        6 months ago        /bin/sh -c #(nop) ADD file:4683e735d1f7a57fd5   864 B
da64e86860ea        6 months ago        /bin/sh -c mkdir /etc/service/gunicorn          7 B
9109839d1887        6 months ago        /bin/sh -c touch /var/log/gunicorn/error.log    7 B
5e628a947f45        6 months ago        /bin/sh -c touch /var/log/gunicorn/access.log   7 B
57b25445ef0b        6 months ago        /bin/sh -c mkdir /var/log/gunicorn              7 B
dc008bbf46e8        6 months ago        /bin/sh -c /var/www/venv/bin/django-admin.py    747.5 kB
d75444a0b891        6 months ago        /bin/sh -c /var/www/venv/bin/django-admin.py    45.49 kB
4b6f8f5021aa        6 months ago        /bin/sh -c #(nop) ENV SECRET_KEY=no-so-secret   0 B
93a3749a8817        6 months ago        /bin/sh -c #(nop) ENV DJANGO_SETTINGS_MODULE=   0 B
3d67fca00fe8        6 months ago        /bin/sh -c #(nop) ENV PYTHONPATH=$PYTHONPATH:   0 B
1b2851b048f7        6 months ago        /bin/sh -c /var/www/venv/bin/pip install -r /   30.19 MB
7c9a3b2daefb        6 months ago        /bin/sh -c virtualenv /var/www/venv             11.62 MB
6b468cc8cefe        6 months ago        /bin/sh -c pip install virtualenv               1.921 MB

Dockerfiles (builder)

Series of commands to build an image

# 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
...

Docker Engine

Manages containers on your machine

Docker Hub

Common registry of Docker images

Docker

Repository

Git

Repository

collection of commits

Container

Checkout

used for local execution

Docker Hub

GitHub

popular remote server

Image

Commit

saved state