This document discusses Docker, an open source engine that allows developers to easily create lightweight, portable containers from applications. Docker makes it easy to deploy applications across multiple environments, eliminating compatibility issues. It works by using Linux containers (LXC) and features like namespaces and control groups to isolate resources for each container. Docker provides a simple API and workflow to build images for each application service and link them together across environments like development, testing and production.

1. Anil Wadghule
awadghule@equalexperts.com
February 2014 — Docker 0.8.0

2. Docker
•
Docker was started by Solomon Hykes as an internal project by
dotCloud
•
Docker makes Linux Containers easy to use

3. What is Docker?
“Docker is an open source engine to easily create lightweight,
portable, self-sufficient containers from any application. The same
container that a developer builds and tests on a laptop can run at
scale, in production, on VMs, bare metal, OpenStack clusters, public
clouds and more” - http://docker.io

4. Why Docker?
•
Deploy everything (webapps, backends, sql, big data, message
queues)
•
Deploy almost everywhere (Linux servers, VMs or bare metal, any
distro, Kernel 3.8)
•
Deploy reliably & consistently (local and on server same)
•
Deploy easily
•
Deploy at scale

5. Docker popularity
•
330+ Contributors,
•
50,000+ docker index pull,
•
1000’s of Dockerized applications
•
Integration in Jenkins, Travis, Chef, Puppet, Vagrant & OpenStack

6. The challenge
•
Static website, User DB, Queue, Background workers, Analytics DB,
API endpoint, Web Frontend
•
Development VM, QA Server, Public cloud, Production Servers,
Customer data center, Production cluster
•
Running apps in multiple environments results in N x N nightmare

7. Problem: shipping code
N x N compatibility nightmare

8. Solution
•
The Linux Container

9. This eliminated the N x N problem

10. What is LXC?
•
Lightweight Linux Container (LXC)
•
Operating system level virtualisation method for running multiple
isolated Linux systems
•
Provides way to run mini Linux systems within another Linux systems
•
http://en.wikipedia.org/wiki/LXC

11. LXC
•
I can SSH into it
•
I have root access
•
I can apt-get/yum install packages
•
Speed: boots in seconds
•
Footprint: 100-1000 containers on one machine. Small disk
requirements.

12. Control groups & namespaces
•
LXCs makes use of control groups & namespaces
•
Linux kernel feature to limit, account and isolate resource usage,
such as
— CPU
— Memory
— Disk I/O

13. Docker
•
Docker is API on top of LXC
•
Docker runs as daemon
•
Docker makes Linux Containers easy to use (LXC)
•
Docker service exposes REST api that is used by Docker client

14. Docker architecture
DOCKER
LXC
LAYER FS
CGROUPS
LINUX KERNEL
NAMESPACES

15. Container vs. VMs

16. Docker operating system?
•
Doesn’t include operating system
•
Relies on operating system functionality provided by underlying
infrastructure

17. Requirements
•
Linux kernel 3.8 & above
•
AUFS
•
LXC
•
64-bit

18. Installation
•
Can be directly installed on supported Linux distros.
•
Supported Ubuntu versions
Ubuntu Precise 12.04 (LTS) (64-bit)
Ubuntu Raring 13.04 and Saucy 13.10 (64 bit)

19. Installation: boot2docker
On Mac
•
$ brew install boot2docker
$ boot2docker init
$ boot2docker up
$ export DOCKER_HOST=tcp://
$ docker run -i -t busybox sh
#/

20. Installation: Vagrant
•
Clone the docker repository
$ git clone https://github.com/dotcloud/docker.git
•
Startup the vagrant image
$ vagrant up
•
SSH into the image
$ vagrant ssh
•
Use docker in VM
$ docker
•
Vagrant client works on Mac

21. Demo

22. What Docker has done?
•
Downloaded the image from docker repo
•
Generated a new LXC container
•
Created a new file system
•
Mounted a read/write layer
•
Allocated network interface
•
Setup IP Setup NATing
•
Executed the bash shell in the container
•
** All under a very few minutes

23. Advantages
•
Elegant application delivery
•
Throwable sandboxes
•
Create uniform development & production environments
•
Automated testing and continuous integration/deployments
•
Deploying and scaling web apps, databases and backend services

24. Why developers care?
•
Build once, write everywhere
•
Clean, safe, hygienic and portable runtime environment for app
•
No worries about missing dependencies during subsequent
deployments
•
Reduce / eliminate compatibility concerns on different platforms

25. Recommended workflow
•
Each service will be in its own container(s)
•
Build an image for each service
•
Pin dependencies (packages etc.) accurately.
•
Link services together

26. Questions

27. Thank you !!!
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@anildigital