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Ruby and on Rails
Muriel Salvan
X-Aeon Solutions
Feb 04th 2014
Riviera.rb
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Who am I?
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Muriel Salvan
Freelance Developer
Founder of X-Aeon Solutions
Open Source advocate
Ruby / Rails expert
Co-founder of RivieraRB
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Let's talk about cargo transport
(that's why you came here, right?)
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"I want my piano to be delivered
from Nice to London"
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"I also want my barrel of wine
delivered from Nice to London."
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"Hey! Don't forget my bags of rice
too!"
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How ?
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"By train, plane, boat, truck, bus,
mule, or whatever!"
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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)
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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
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Static website
Web frontend
User DB
Queue Analytics DB
Background workers
API endpoint
Development VM
QA server
Public Cloud
Disaster recovery Contributor’s laptop
Production Servers
Production Cluster
Customer Data Center
Do services and apps
interact appropriately?
Can I migrate smoothly and
quickly?
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Static website
Web frontend
User DB
Queue
Analytics DB
Background workers
API endpoint
Development VM
QA server
Public Cloud
Disaster recovery
Contributor’s laptop
Production Servers
Production Cluster
Customer Data Center
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So what does Docker bring?
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1- File systems images
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Structured in layers (storing diffs only)
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Layers are reused between images
Clever!
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2- Processes run in a contained
environment (containers)
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Using images' file systems
(isolated like in chroot)
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In a separate process space
(using Linux containers)
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With a specific network interface
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Can run as root
It's chroot on steroids!
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3- A public repository of images
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Pull and push images
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Build them from Github projects
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Be part of a great community!
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"Is it a yet-another-virtualization-
solution?"
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No.
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Processes run by Docker
share the host Kernel
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No device emulation
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No boot sequence
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Architectures and platforms
between Host and containers
must match
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"So where is the portability?"
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Containers can be run on any Kernel
(>= 3.8, Linux 64b only for now)
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Whatever the Linux distro
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If it runs on the Host, it can run from
a container
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Physical, virtual, cloud...
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It's blazingly fast!!!
A few ms to load the container and run the
command
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Use cases
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Get running clusters on a single host
Awesome to test them!
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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!
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Deployments become sooo easy
Like "push"-and-"pull"-easy!
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Lightweight virtualization too
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"How do we create images?"
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Docker files
Describe commands to be run to create an image
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# Nginx
#
# VERSION 0.0.1
FROM ubuntu
MAINTAINER Guillaume J. Charmes
# 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
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docker build .
Docker file
Image
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"And how do we run a process in a
container?"
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docker run ![]()
Image
Container
running
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"I want to create a modified image"
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docker commit ![]()
Image
Container
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"Hey! I want to deploy my image for
the world to see!"
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docker push ![]()
Image
Registry
Defaults to
http://index.docker.io
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"And now my friend wants to get my
wonderful image to play with!"
Yeah, sure... whatever
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docker search ![]()
docker pull ![]()
Image
Registry
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"Wasn't that supposed to be a Ruby
meetup?"
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Let's simulate a Rails cluster with a
balancing Ruby proxy in front!
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Docker container
B
Docker container
B
Docker container
B
Docker container
B
Docker container
B
Docker container
A
3000
3000 3000
3000 3000
5000 5001 5002 5003 5004
3000
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1. Create a Ruby image:
murielsalvan/ruby
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From ubuntu base image
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Using a Dockerfile
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Bonus: Upload it to index.docker.io via Github
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# Ruby environment
#
# VERSION 0.2
FROM ubuntu
MAINTAINER Muriel Salvan
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
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2. Create a Rails server image:
murielsalvan/server
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From murielsalvan/ruby base image
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Using an interactive bash in a container to install and
configure the Rails application
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Add a startup command: rails s
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Open default port 3000
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3. Launch n docker containers from
murielsalvan/server
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Map each container port 3000 to host ports 5000+i
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4. Create a new image for the Ruby
proxy: murielsalvan/proxy
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Based on murielsalvan/ruby
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Using an interactive bash to install and use em-proxy,
targetting servers on ports 5000+i
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Add a startup command: ruby -w balancing.rb
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Open port 3000
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5. Launch 1 docker container from
murielsalvan/proxy
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Map its guest port 3000 to host port 3000
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6. Target localhost:3000
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7. Profit!
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Without Docker With Docker
0
5
10
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30
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45
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Elapsed time (s) on Fibonacci computation
Launch time
Execution time
Sponsored by the
WTF effect!
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RSS VSZ
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20000
40000
60000
80000
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180000
Memory consumption per container (kB)
Rails
Linux container
The Linux container memory is always the same whatever the process in the container:
1,5MB RSS and 32MB VSZ
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NOT BAD
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Links
Homepage
Index of Docker images
Dockerfile reference
Getting started
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Source: xkcd
That's all, folks!
Thanks for attending!