This document summarizes Muriel Salvan's presentation on Docker and cargo transport. It discusses how Docker can be used to containerize applications and services, create images from Dockerfiles, run containers from images, and deploy images to registries for sharing. Examples are given on building Ruby and Rails images, running a clustered Rails application in containers, and using a proxy container to load balance requests. Performance benefits of Docker are highlighted such as faster launch times and consistent memory usage across containers.

1. Ruby and
Muriel Salvan
X-Aeon Solutions
Feb 04th 2014
Riviera.rb
on Rails

2. Who am I?

3. Muriel Salvan
Freelance Developer
Founder of X-Aeon Solutions
Open Source advocate
Ruby / Rails expert
Co-founder of RivieraRB

4. @MurielSalvan
Github
SourceForge
My tech blog
Muriel@X-Aeon.com

5. Let's talk about cargo transport
(that's why you came here, right?)

6. "I want my piano to be delivered
from Nice to London"

7. "I also want my barrel of wine
delivered from Nice to London."

8. "Hey! Don't forget my bags of rice
too!"

9. How ?

10. "By train, plane, boat, truck, bus,
mule, or whatever!"

11. Do I worry about how goods interact
(e.g. coffee beans next to spices)
Can I transport quickly and smoothly
(e.g. from boat to train to truck)

13. A standard container that is loaded with virtually any
goods, and stays sealed until it reaches final delivery.
…in between, can be loaded and unloaded, stacked,
transported efficiently over long distances, and
transferred from one mode of transport to another

15. Static website
Do services and apps
User DB
Queue
interact appropriately?
Web frontend
Background workers
Development VM
Analytics DB
API endpoint
Production Cluster
Public Cloud
QA Can I migrate smoothly and
server
Disaster recovery Contributor’s laptop
quickly?
Customer Data Center
Production Servers

16. Static website
User DB
Queue
Analytics DB
Background workers
API endpoint
Web frontend
Production Cluster
QA server
Customer Data Center
Development VM
Disaster recovery
Production Servers
Contributor’s laptop
Public Cloud

17. So what does Docker bring?

18. 1- File systems images
Structured in layers (storing diffs only)
● Layers are reused between images
●
Clever!

19. 2- Processes run in a contained
environment (containers)
It's chroot on steroids!
Using images' file systems
(isolated like in chroot)
● In a separate process space
(using Linux containers)
● With a specific network interface
● Can run as root
●

20. 3- A public repository of images
Pull and push images
● Build them from Github projects
● Be part of a great community!
●

21. "Is it a yet-another-virtualizationsolution?"

22. No.

23. Processes run by Docker
share the host Kernel
● No device emulation
● No boot sequence
● Architectures and platforms
between Host and containers
must match
●

24. "So where is the portability?"

25. ●
Containers can be run on any Kernel
(>= 3.8, Linux 64b only for now)
Whatever the Linux distro
● If it runs on the Host, it can run from
a container
● Physical, virtual, cloud...
●

26. It's blazingly fast!!!
A few ms to load the container and run the
command

27. Use cases

28. Get running clusters on a single host
Awesome to test them!

29. Ensure the environment your process
runs in is the same in dev, test and
prod
Bring your environment along with your process.
Sandboxes everywhere!
You'll love that!

30. Deployments become sooo easy
Like "push"-and-"pull"-easy!

31. Lightweight virtualization too

33. "How do we create images?"

34. Docker files
Describe commands to be run to create an image

35. # Nginx
#
# VERSION
0.0.1
FROM
ubuntu
MAINTAINER Guillaume J. Charmes
<guillaume@dotcloud.com>
# make sure the package repository is up to date
RUN echo "deb http://archive.ubuntu.com/ubuntu precise
main universe" > /etc/apt/sources.list
RUN apt-get update
RUN apt-get install -y inotify-tools nginx apache2
openssh-server

36. Docker file
docker build .
Image

37. "And how do we run a process in a
container?"

38. Image
docker run <image> <cmd>
Container
running <Cmd>

39. "I want to create a modified image"

40. Container
docker commit <container> <image name>
Image

41. "Hey! I want to deploy my image for
the world to see!"

42. Image
docker push <image>
Registry
Defaults to
http://index.docker.io

43. "And now my friend wants to get my
wonderful image to play with!"
Yeah, sure... whatever

44. Registry
docker search <image name>
docker pull <image>
Image

46. "Wasn't that supposed to be a Ruby
meetup?"

47. Let's simulate a Rails cluster with a
balancing Ruby proxy in front!

48. 3000
Docker container
A
5000
5001
5002
5003
5004
3000
3000
3000
3000
3000
Docker container Docker container Docker container Docker container Docker container
B
B
B
B
B

49. 1. Create a Ruby image:
murielsalvan/ruby
From ubuntu base image
● Using a Dockerfile
● Bonus: Upload it to index.docker.io via Github
●

50. # Ruby environment
#
# VERSION 0.2
FROM ubuntu
MAINTAINER Muriel Salvan <muriel@x-aeon.com>
RUN echo "deb http://archive.ubuntu.com/ubuntu precise main universe" > /etc/apt/sources.list
RUN apt-get update
RUN apt-get upgrade -y
RUN apt-get install -y build-essential zlib1g-dev libssl-dev libreadline6-dev libyaml-dev
ADD http://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.0.tar.gz /tmp/
RUN cd /tmp &&
tar -xzf ruby-2.1.0.tar.gz &&
cd ruby-2.1.0 &&
./configure &&
make &&
make install &&
cd .. &&
rm -rf ruby-2.1.0 &&
rm -f ruby-2.1.0.tar.gz

51. 2. Create a Rails server image:
murielsalvan/server
From murielsalvan/ruby base image
● Using an interactive bash in a container to install and
configure the Rails application
● Add a startup command: rails s
● Open default port 3000
●

52. 3. Launch n docker containers from
murielsalvan/server
●
Map each container port 3000 to host ports 5000+i

53. 4. Create a new image for the Ruby
proxy: murielsalvan/proxy
Based on murielsalvan/ruby
● Using an interactive bash to install and use em-proxy,
targetting servers on ports 5000+i
● Add a startup command: ruby -w balancing.rb
● Open port 3000
●

54. 5. Launch 1 docker container from
murielsalvan/proxy
●
Map its guest port 3000 to host port 3000

55. 6. Target localhost:3000

56. 7. Profit!

58. Elapsed time (s) on Fibonacci computation
Sponsored by the
WTF effect!
50
45
40
35
30
Launch time
Execution time
25
20
15
10
5
0
Without Docker
With Docker

59. Memory consumption per container (kB)
180000
160000
140000
120000
Rails
Linux container
100000
80000
60000
40000
20000
0
RSS
VSZ
The Linux container memory is always the same whatever the process in the container:
1,5MB RSS and 32MB VSZ

60. NOT BAD

61. Links
Homepage
Index of Docker images
Dockerfile reference
Getting started

62. That's all, folks!
Source: xkcd
Thanks for attending!