Ruby and Docker on Rails

Quick overview of Docker and its usage.
Illustrated with a cluster of Rails applications and a Ruby load balancing proxy on top of them.
This presentation was made during the rivierarb meetup in Sophia-Antipolis on 2014 Feb 04th by Muriel Salvan.

Transcript

1. Ruby and on Rails Muriel Salvan X-Aeon Solutions Feb 04th 2014 Riviera.rb
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 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?
16. 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
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) • 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 It's chroot on steroids!
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-virtualization- solution?"
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 build . Docker file Image
37. "And how do we run a process in a container?"
38. docker run <image> <cmd> Image Container running <Cmd>
39. "I want to create a modified image"
40. docker commit <container> <image name> Image Container
41. "Hey! I want to deploy my image for the world to see!"
42. docker push <image> 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. docker search <image name> docker pull <image> Image Registry
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. 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
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. Without Docker With Docker 0 5 10 15 20 25 30 35 40 45 50 Elapsed time (s) on Fibonacci computation Launch time Execution time Sponsored by the WTF effect!
59. RSS VSZ 0 20000 40000 60000 80000 100000 120000 140000 160000 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
60. NOT BAD
61. Links Homepage Index of Docker images Dockerfile reference Getting started
62. Source: xkcd That's all, folks! Thanks for attending!