This document discusses Docker and Puppet for DevOps. It introduces Docker as a lightweight virtualization tool for containers and compares it to virtual machines. Puppet is a configuration management tool. The document outlines how Puppet can be used to install and configure Docker ("Puppetizing Docker") and how Docker can be used to deploy systems configured with Puppet ("Dockerizing Puppet"). It proposes ideas for the future like using Puppet to output Dockerfiles instead of configuring systems directly and having a single Puppet agent manage multiple containers.

1. Docker
and
Puppet

2. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

3. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

4. @jpetazzo
●
Wrote dotCloud PAAS deployment tools
–EC2,
●
LXC, Puppet, Python, Shell, ØMQ...
Docker contributor
–Docker-in-Docker,
VPN-in-Docker,
router-in-Docker... CONTAINERIZE ALL THE THINGS!
●
Runs Docker in production
–You
shouldn't do it, but here's how anyway!

5. You
●
Puppet?
●
Production?
●
Cloud?
●
Docker?

6. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

8. The promise
●
●
●
●
CONTAINERS boot faster
(than VMs)
CONTAINERS have less overhead
(more consolidation)
CONTAINERS bring native performance
(on bare metal)
CONTAINERS are cloud-compatible
(can run in VMs)

9. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

10. Hypervisor for containers
●
Xen, KVM, VMWare... deal with VMs
●
Docker deals with containers (currently LXC)

11. Wait, what's a container?

12. High level approach:
it's a lightweight VM
●
own process space
●
own network interface
●
can run stuff as root
●
can have its own /sbin/init
(different from the host)
« Machine Container »

13. Low level approach:
it's chroot on steroids
●
can also not have its own /sbin/init
●
container = isolated process(es)
●
share kernel with host
●
no device emulation (neither HVM nor PV)
« Application Container »

14. How does it work?
Isolation with namespaces
●
pid
●
mnt
●
net
●
uts
●
ipc
●
user

15. How does it work?
Isolation with cgroups
●
memory
●
cpu
●
blkio
●
devices

16. How does it work?
Copy-on-write storage
●
●
●
Create a new machine instantly
(Instead of copying its whole filesystem)
Storage keeps track of what has changed
Since 0.7, Docker has a storage plugin system
(supports AUFS, thin snapshots, BTRFS, VFS)

17. Container format
●
VM images have drawbacks
–
–
non-standard; conversions possible but slow
–
●
big, bulky, require special tools (and/or root)
snapshots possible but even less standard
Container images are better
–
small, can be handled with tar
–
simple delta snapshots

18. Build system (1/2)
●
Shell scripts
–
–
●
OK-ish for simple stacks
Tricky to handle all possible situations
(that's why we have proper CM)
Puppet (and others)
–
Great for convergence and repeatability
–
Steep learning curve

19. Build system (2/2)
●
Dockerfile!
–
Doesn't have to deal with « low-level stuff »
–
Doesn't need all the goodness of CM
–
If you know Shell, you already know Dockerfile
–
Layered caching (only rebuild what's needed)
–
Allows inheritance and composition

20. FROM ubuntu
RUN
RUN
RUN
RUN
RUN
apt-get
apt-get
apt-get
apt-get
apt-get
-y update
install -y
install -y
install -y
install -y
g++
erlang-dev erlang-manpages erlang-base-hipe ...
libmozjs185-dev libicu-dev libtool ...
make wget
RUN wget http://.../apache-couchdb-1.3.1.tar.gz | tar -C /tmp -zxfRUN cd /tmp/apache-couchdb-* && ./configure && make install
RUN printf "[httpd]nport = 8101nbind_address = 0.0.0.0" >
/usr/local/etc/couchdb/local.d/docker.ini
EXPOSE 8101
CMD ["/usr/local/bin/couchdb"]
docker build -t jpetazzo/couchdb .

21. REST API
●
Docker = daemon with REST API
●
CLI = client for that REST API
●
Many tools already available
–
dashboards, GUIs...
–
orchestration (Maestro NG and more)
–
OpenStack, PAAS, Mesos...

22. Open Source
●
Docker repo on GitHub
–
–
●
More than 340 contributors and 1500 forks
Hint: Docker Inc. headcount is less than 34...
Communication channels
–
Mailing lists: docker-user and docker-dev
–
IRC (Freenode): #docker and #docker-dev

24. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

25. First things first
https://github.com/garethr/garethr-docker
https://forge.puppetlabs.com/garethr/docker

26. Installing Docker with Puppet
include 'docker'
class { 'docker':
version => '0.8.1'
}

27. Warm up our image collection
# download the registry image
docker::image { 'stackbrew/registry':
}
# don't download all ubuntu,
# just 'precise'
docker::image { 'ubuntu':
image_tag => 'precise'
}

28. Run containers
docker::run { 'slavedb':
image
=> 'jpetazzo/postgresql'
}
command
ports
links
use_name
volumes
volumes_from
memory_limit
username
hostname
env
dns
restart_service
=>
=>
=>
=>
=>
=>
=>
=>
=>
=>
=>
=>
'…'
['5432', '22'],
['masterdb:master'],
true,
['/var/lib/postgresql'],
'420fc7e8aa20',
100000000, # bytes
'postgres',
'sdb.prod.dckr.io',
['FUZZINESS=42', FOO=BAR', 'FOO2=BAR2'],
['8.8.8.8', '8.8.4.4'],
true

29. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

30. My other VM is a container
●
write a Dockerfile to install $YOUR_CM
●
start tons of containers
●
run $YOUR_CM in them
Good if you want a mix of containers/VM/metal
But slower to deploy, and uses more resources

31. Sample Dockerfile
FROM ubuntu:12.04
RUN apt-get install -qy wget
RUN mkdir /puppet
WORKDIR /puppet
RUN wget -q http://apt.puppetlabs.com/puppetlabs-release-precise.deb
RUN dpkg -i puppetlabs-release-precise.deb
RUN apt-get update -q
RUN apt-get install -qy puppet-common
CMD puppet agent --no-daemonize --verbose

32. Lightweight, portable VMs
●
Start containers instead of VMs
–
–
You can start those 10 containers too!
(Even though you have a totally different laptop!)
–
●
I can start 10 containers on this puny laptop!
We can start those containers in the Cloud!
Deploy sshd, syslogd, crond, etc.
–
You can... But do you have to?

33. The revolution will be containerized
●
write a Dockerfile to install $YOUR_CM
●
… and run $YOUR_CM as part of build process
●
deploy fully baked images
Faster to deploy
Easier to rollback

34. Sample Dockerfile
FROM ubuntu:12.04
RUN apt-get install -qy wget
RUN mkdir /puppet
WORKDIR /puppet
RUN wget -q http://apt.puppetlabs.com/puppetlabs-release-precise.deb
RUN dpkg -i puppetlabs-release-precise.deb
RUN apt-get update -q
RUN apt-get install -qy puppet-common
ENV FACTER_HOSTNAME database42
ADD ./site.pp /puppet/site.pp
RUN puppet apply site.pp

36. Outline
●
Intros
●
What's the point?
●
Docker for DevOps
●
Puppetizing Docker
●
Dockerizing Puppet
●
What's next?

37. Docker provisioner
What if...
●
●
●
Puppet doesn't act on the system,
outputs a Dockerfile instead?
Puppet builds this Dockerfile,
and pushes the resulting image to a registry?
One node can build images,
while other nodes run those images?

38. A better Puppet agent
●
Puppet agent is OK on « big » machines
●
Not so much on small containers
●
●
Can we run a single agent,
and have it « rotate » between containers?
Can we run that agent...
… in a container?

39. Thank you! Questions?
http://docker.io/
http://docker.com/
@docker
@jpetazzo