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

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

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

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

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

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

N x N compatibility nightmare Problem: shipping code

Solution • The Linux Container

This eliminated the N x N problem

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

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.

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

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

Docker architecture DOCKER LAYER FS LXC CGROUPS LINUX KERNEL NAMESPACES

Container vs. VMs

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

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

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)

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

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

Demo

• 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 What Docker has done?

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

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

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

Questions

Thank you !!! Follow me on Twitter @anildigital