Docker and Puppet — Puppet Camp L.A. — SCALE12X

Outline
●

Intros

●

What's the point?

●

Docker for DevOps

●

Puppetizing Docker

●

Dockerizing Puppet

●

What's next?

@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!

You
●

Puppet?

●

Production?

●

Cloud?

●

Docker?

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)

Hypervisor for containers
●

Xen, KVM, VMWare... deal with VMs

●

Docker deals with containers (currently LXC)

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 »

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 »

How does it work?
Isolation with namespaces
●

pid

●

mnt

●

net

●

uts

●

ipc

●

user

How does it work?
Isolation with cgroups
●

memory

●

cpu

●

blkio

●

devices

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)

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

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

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

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 .

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...

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

First things first

https://github.com/garethr/garethr-docker
https://forge.puppetlabs.com/garethr/docker

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

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'
}

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

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

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

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?

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

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

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?

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?

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

Docker and Puppet — Puppet Camp L.A. — SCALE12X

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