The document provides an introduction to Docker, containers, and the problems they aim to solve. It discusses: - Why Docker was created - to address the "matrix from hell" of developing and deploying applications across different environments and platforms. - How Docker works at a high level, using lightweight containers that package code and dependencies to run consistently on any infrastructure. - Some key Docker concepts like images, containers, the Dockerfile for building images, and common Docker commands. - Benefits of Docker for developers and operations in simplifying deployment, reducing inconsistencies, and improving portability of applications.

1. Introduction to Docker
January, 2016
@sujai_mba

2. Agenda
• Introduction to Docker, Containers, and the Matrix from Hell
• Why people care: Separation of Concerns?
• How Docker works?
• Technical explanation
• Containers vs VMs
• Basics of Docker System
• Docker File
• Docker CLI Commands

3. Static website
Web frontend
User DB
Queue Analytics DB
Background workers
API endpoint
nginx 1.5 + modsecurity + openssl + bootstrap 2
postgresql + pgv8 + v8
hadoop + hive + thrift + OpenJDK
Ruby + Rails + sass + Unicorn
Redis + redis-sentinel
Python 3.0 + celery + pyredis + libcurl + ffmpeg + libopencv + nodejs +
phantomjs
Python 2.7 + Flask + pyredis + celery + psycopg + postgresql-client
Development VM
QA server
Public Cloud
Disaster recovery
Contributor’s laptop
Production Servers
The ChallengeMultiplicityofStacks
Multiplicityof
hardware
environments
Production Cluster
Customer Data Center
Doservicesandapps
interact
appropriately?
CanImigrate
smoothlyand
quickly?

4. The Matrix From Hell
Static website
Web frontend
Background workers
User DB
Analytics DB
Queue
Development
VM
QA Server
Single Prod
Server
Onsite
Cluster
Public Cloud
Contributor’s
laptop
Customer
Servers
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?

5. MultiplicityofGoods
Multipilicityof
methodsfor
transporting/storing
DoIworryabout
howgoodsinteract
(e.g.coffeebeans
nexttospices)
CanItransportquickly
andsmoothly
(e.g.fromboattotrain
totruck)
Cargo Transport Pre-1960

6. ? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
? ? ? ? ? ? ?
Also a matrix from hell

7. MultiplicityofGoods
Multiplicityof
methodsfor
transporting/storing
DoIworryabout
howgoodsinteract
(e.g.coffeebeans
nexttospices)
CanItransport
quicklyandsmoothly
(e.g.fromboatto
traintotruck)
Solution: Intermodal Shipping Container
…in between, can be loaded and
unloaded, stacked, transported
efficiently over long distances,
and transferred from one mode
of transport to another
A standard container that is
loaded with virtually any
goods, and stays sealed until
it reaches final delivery.

8. Static website Web frontendUser DB Queue Analytics DB
Development
VM
QA server Public Cloud Contributor’s
laptop
Docker is a shipping container system for
code
MultiplicityofStacks
Multiplicityof
hardware
environments
Production
Cluster
Customer Data
Center
Doservicesandapps
interact
appropriately?
CanImigrate
smoothlyandquickly
…that can be manipulated using
standard operations and run
consistently on virtually any
hardware platform
An engine that enables any
payload to be encapsulated
as a lightweight, portable,
self-sufficient container…

9. Static website
Web frontend
Background workers
User DB
Analytics DB
Queue
Development
VM
QA Server
Single Prod
Server
Onsite
Cluster
Public Cloud
Contributor’s
laptop
Customer
Servers
Docker eliminates the matrix from Hell

10. Why Developers Care
• Build once…(finally) run anywhere*
• A clean, safe, hygienic and portable runtime environment for your app.
• No worries about missing dependencies, packages and other pain points during
subsequent deployments.
• Run each app in its own isolated container, so you can run various versions of libraries
and other dependencies for each app without worrying
• Automate testing, integration, packaging
• Reduce/eliminate concerns about compatibility on different platforms, either your own
or your customers.

11. Why Devops Cares?
• Configure once…run anything
• Make the entire lifecycle more efficient, consistent, and repeatable
• Increase the quality of code produced by developers.
• Eliminate inconsistencies between development, test, production, and customer
environments
• Significantly improves the speed and reliability of continuous deployment and continuous
integration systems
• Because the containers are so lightweight, costs, deployment, and portability issues
normally are associated with VMs

12. How Docker Works
• You can build Docker images that hold your applications
• You can create Docker containers from those Docker images
to run your applications.
• You can share those Docker images via Docker Hub or your
own registry

13. More technical explanation
• High Level—It’s a lightweight VM
• Own process space
• Own network interface
• <<machine container>>
• Low Level—It’s chroot on
steroids
• Container=isolated processes
• Share kernel with host
• <<application container>>
• Run everywhere
• Regardless of kernel version
(2.6.32+)
• Regardless of host distro
• Physical or virtual, cloud or not
• Container and host
architecture must match*
• Run anything
• If it can run on the host, it can
run in the container
• i.e. if it can run on a Linux
kernel, it can run
WHY WHAT

14. App
A
Containers vs. VMs
Hypervisor (Type 2)
Host OS
Server
Guest
OS
Bins/
Libs
App
A’
Guest
OS
Bins/
Libs
App
B
Guest
OS
Bins/
Libs
AppA’
Docker
Host OS
Server
Bins/Libs
AppA
Bins/Libs
AppB
AppB’
AppB’
AppB’
VM
Container
Containers are isolated,
but share OS and, where
appropriate, bins/libraries
Guest
OS
Guest
OS
…result is significantly faster deployment,
much less overhead, easier migration,
faster restart

15. Why are Docker containers lightweight?
Bins/
Libs
App
A
Original App
(No OS to take up
space, resources,
or require restart)
AppΔ
Bins/
App
A
Bins/
Libs
App
A’
Guest
OS
Bins/
Libs
Modified App
Copy on write
capabilities allow us to
only save the diffs
Between container A
and container A’
VMs
Every app, every copy of an
app, and every slight modification
of the app requires a new virtual server
App
A
Guest
OS
Bins/
Libs
Copy of App
No OS. Can
Share bins/libs
App
A
Guest
OS
Guest
OS
VMs
Containers

16. Basics of the Docker system
Source
Code
Repository
Dockerfile
For
A
Docker Engine
Docker
Image
Registry
Build
Docker
Host 2 OS (Linux)
ContainerA
ContainerB
ContainerC
ContainerA
Push
Search
Pull
Run
Host 1 OS (Linux)
Docker Image
Run

17. Changes and Updates
Docker Engine
Docker
Image
Registry
Docker Engine
Push
Update
Bins/
Libs
App
A
Base
Image
Host is now running A’’
Container
Mod A’’
AppΔ
Bins/
Bins/
Libs
App
A
Bins/
Bins/
Libs
App
A’’
Host running A wants to upgrade to A’’.
Requests update. Gets only diffs
Container
Mod A’
Bins/
AppΔ

18. Docker File
• Like a Makefile (shell script with keywords)
• Extends from a Base Image
• Results in a new Docker Image
• Imperative, not Declarative
• A Docker file lists the steps needed to build an images
• docker build is used to run a Docker file
• Can define default command for docker run, ports to expose, etc

19. Docker CLI Commands

20. www.docker.io
Thank You!