CoreOS CloudInit Config for Docker Storage Management

CoreOS is a Linux distribution that allows easy deployment of Docker environments.  With CoreOS, users have the ability to deploy clustered Docker environments,  or deploy zero downtime applications.  Recently, I have blogged about how to deploy and use Docker on Eucalyptus cloud environments. This blog will focus on how to leverage cloud-init configuration with a CoreOS EMI to manage instance storage that will be used by Docker containers on Eucalyptus 4.0.  The same cloud-init configuration file can be used  on AWS with CoreOS AMIs, which is yet another example of how Eucalyptus has continued to maintain its focus on being the best on-premise AWS compatible cloud environment.


Since Eucalyptus Identity and Access Management (IAM) is very similar to AWS’s IAM, at a minimum – the following Elastic Compute Cloud (EC2) actions need to be allowed:

In order to bundle, upload and register the CoreOS image, use the following AWS S3 policy (which can be generated using AWS Policy Generator):

  "Statement": [
      "Sid": "Stmt1402675433766",
      "Action": "s3:*",
      "Effect": "Allow",
      "Resource": "*"

For more information about how to use Eucalyptus IAM, please refer to the Eucalyptus 4.0 Administrator documentation regarding access concepts and policy overview.

In addition to the correct IAM policy being applied to the user, here are the other prerequisites that need to be met:

Once these prerequisites are met, the Eucalyptus user will be able to implement the topic for this blog.

CoreOS CloudInit Config for Docker Storage Management

As mentioned in the CoreOS documentation regarding how to use CoreOS with Eucalyptus, the user needs to do the following:

  • Download the CoreOS image
  • Decompress the CoreOS image
  • Bundle, upload and register the image

For example:

# wget -q

# bunzip2 coreos_production_openstack_image.img.bz2

# qemu-img convert -O raw coreos_production_openstack_image.img coreos_production_openstack_image.raw
# euca-bundle-and-upload-image -i coreos_production_openstack_image.raw -b coreos-production-beta -r x86_64
# euca-register -n coreos-production coreos-production-beta/coreos_production_openstack_image.raw.manifest.xml --virtualization-type hvm
IMAGE emi-98868F66

After the image is registered, create a security group and authorize port 22 for SSH access to the CoreOS instance:

# euca-create-group coreos-testing -d "Security Group for CoreOS Cluster"
GROUP sg-C8E3B168 coreos-testing Security Group for CoreOS Cluster
# euca-authorize -P tcp -p ssh coreos-testing
GROUP coreos-testing
PERMISSION coreos-testing ALLOWS tcp 22 22 FROM CIDR

Next, create a keypair that will be used to access the CoreOS instance:

# euca-create-keypair coreos > coreos.priv
# chmod 0600 coreos.priv

Now, we are need to create the cloud-init configuration file.  CoreOS implements a subset of cloud-init config spec with coreos-cloudinit.  The cloud-init config below will do the following:

  1. wipe the the ephemeral device – /dev/vdb (since the CoreOS EMI is an instance store-backed HVM image, ephemeral device will be /dev/vdb)
  2. format the ephemeral device with BTRFS filesystem
  3. mount /dev/vdb to /var/lib/docker (which is the location for images used by the Docker containers)

Create a cloud-init.config file with the following information:

 - name: format-ephemeral.service
 command: start
 content: |
 Description=Formats the ephemeral drive
 ExecStart=/usr/sbin/wipefs -f /dev/vdb
 ExecStart=/usr/sbin/mkfs.btrfs -f /dev/vdb
 - name: var-lib-docker.mount
 command: start
 content: |
 Description=Mount ephemeral to /var/lib/docker

Use euca-describe-instance-types to select the desired instance type for the CoreOS instance (in this example, c1.medium will be used).

# euca-describe-instance-types 
INSTANCETYPE Name CPUs Memory (MiB) Disk (GiB)
INSTANCETYPE t1.micro 1 256 5
INSTANCETYPE m1.small 1 512 10
INSTANCETYPE m1.medium 1 1024 10
INSTANCETYPE c1.xlarge 2 2048 10
INSTANCETYPE m1.large 2 1024 15
INSTANCETYPE c1.medium 1 1024 20
INSTANCETYPE m1.xlarge 2 1024 30
INSTANCETYPE m2.2xlarge 2 4096 30
INSTANCETYPE m3.2xlarge 4 4096 30
INSTANCETYPE m2.xlarge 2 2048 40
INSTANCETYPE m3.xlarge 2 2048 50
INSTANCETYPE cc1.4xlarge 8 3072 60
INSTANCETYPE m2.4xlarge 8 4096 60
INSTANCETYPE hi1.4xlarge 8 6144 120
INSTANCETYPE cc2.8xlarge 16 6144 120
INSTANCETYPE cg1.4xlarge 16 12288 200
INSTANCETYPE cr1.8xlarge 16 16384 240
INSTANCETYPE hs1.8xlarge 48 119808 24000

Use euca-run-instances to launch the CoreOS image as an instance, passing the cloud-init.config file using the –user-data-file option:

# euca-run-instances -k coreos -t c1.medium emi-98868F66 --user-data-file cloud-init-docker-storage.config
RESERVATION r-FC799274 408396244283 default
INSTANCE i-AF303D5D emi-98868F66 pending coreos 0 c1.medium 2014-06-12T13:38:31.008Z ViciousLiesAndDangerousRumors monitoring-disabled instance-store hvm sg-A5133B59

Once the instance reaches the ‘running’ state, SSH into the instance to see the ephemeral storage mounted and formatted correctly:

# euca-describe-instances i-AF303D5D --region account1-user01@
RESERVATION r-FC799274 408396244283 default
INSTANCE i-AF303D5D emi-98868F66 euca-172-18-238-171.bigboi.internal running coreos 0 c1.medium 2014-06-12T13:38:31.008Z ViciousLiesAndDangerousRumors monitoring-disabled instance-store hvm sg-A5133B59
# ssh -i coreos.priv
CoreOS (beta)
core@localhost ~ $ lsblk
vda 254:0 0 8.3G 0 disk
|-vda1 254:1 0 128M 0 part
|-vda2 254:2 0 64M 0 part
|-vda3 254:3 0 1G 0 part
|-vda4 254:4 0 1G 0 part /usr
|-vda6 254:6 0 128M 0 part /usr/share/oem
`-vda9 254:9 0 6G 0 part /
vdb 254:16 0 11.7G 0 disk /var/lib/docker
core@localhost ~ $ mount
/dev/vda6 on /usr/share/oem type ext4 (rw,nodev,relatime,commit=600,data=ordered
/dev/vdb on /var/lib/docker type btrfs (rw,relatime,space_cache)

The instance is now ready for docker containers to be created.  For some docker container examples, check out the CoreOS documentation and the Docker documentation.


Yet Another AWS Compatibility Example Using Vagrant-AWS Plugin and Eucalyptus 3.4 to Deploy Docker

Something that Eucalyptus has been constant about from the beginning is its stance on being the best open source, on-premise AWS-compatible cloud on the market.   This blog entry is just another example of demonstrating this compatibility.

My most recent blog entries have been centered around Docker and how to deploy it on Eucalyptus.  This entry will show how a user can take Docker’s own documentation on deploying Docker using Vagrant with AWS - but with Eucalyptus.   Before getting started, there are some prerequisites that need to be in place.

Prerequisites for Eucalyptus Cloud

In order to get started, the Eucalyptus cloud needs to have an Ubuntu Raring Cloud Image bundled, uploaded and registered before the steps below can be followed.  The previous blog entries below will help here:

In addition to the Ubuntu Raring Cloud EMI being available, the user also needs to have the following:

After these prerequisites have been met, the user is ready to set up Vagrant to interact with Eucalyptus.

Setting up Vagrant Environment

To start out, we need to set up the Vagrant environment.  The steps below will get you going:

  1. Install Vagrant from (optional – package manager can be used here instead)
  2. Install the vagrant aws plugin:  

    vagrant plugin install vagrant-aws

After Vagrant and the vagrant aws plugin have been successfully installed, all that is left is to create a Vagrantfile to provide information to Vagrant as to how to interact with Eucalyptus.  Since the vagrant aws plugin is being used, and Eucalyptus is compatible with AWS, the configuration will be very similar to AWS.

I provided a Vagrantfile on Github to help get users up to speed quicker.  To check out the Vagrantfile, just clone the repository from Github:

$ git clone

After checking out the file, change directory to eucalyptus-docker-raring, and edit the following variables to match your user information for the Eucalyptus cloud that will run the Docker instance:

AWS_ENDPOINT = "<EC2_URL for Eucalyptus Cloud>"
AWS_AMI = "<ID for Ubuntu Raring EMI>"
AWS_ACCESS_KEY = "<Access Key ID>"
AWS_SECRET_KEY = "<Secret Key>"
AWS_KEYPAIR_NAME = "<Key Pair name>"
SSH_PRIVKEY_PATH = "<The path to the private key for the named keypair, for example ~/.ssh/docker.pem>"

Once the Vagrantfile is populated with the correct information, we are now ready to launch the Docker instance.

Launch the Docker Instance Using Vagrant

From here, Vagrant makes this very straight-forward.  There are only two steps to launch the Docker instance.

  1. Run the following command to launch the instance:

     vagrant up --provider=aws
  2. After Vagrant finishes deploying the instance, SSH into the instance:

    vagrant ssh

Thats it!  Once you are SSHed into the instance, to run Docker, execute the following command:

ubuntu@euca-172-17-120-212:~$ sudo docker

You have successfully launched a Docker instance on Eucalyptus using Vagrant.  Since Eucalyptus works with the vagrant aws plugin, the same Vagrantfile can be used against AWS (of course, the values for the variables above will change).  This is a perfect dev/test to production setup whether Eucalyptus is being used for dev/test and AWS being used for production (and vise versa).

Deploying CentOS 6.5 Image in Docker on Eucalyptus 3.4

This blog entry is a follow-up of my blog entry entitled “Step-by-Step Deployment of Docker on Eucalyptus 3.4 for the Cloud Administrator“.  In that blog entry, I covered how to deploy an Ubuntu Raring Cloud Image on Eucalyptus, and use that image to deploy Docker.   The really cool thing about Docker is that it provides the ability to deploy different operating systems within one machine – in this case, an instance.   The focus of this entry is to show how to deploy a CentOS 6.5 image in a instance running Docker on Eucalyptus 3.4.


The prerequisites for this blog is to complete the steps outlined in my previous blog about Docker on Eucalyptus 3.4.  Once those steps are completed by the cloud administrator (i.e. a user associated with the ‘eucalyptus’ account), you can get started  on the steps below.  One thing to note here, to follow these steps, there is no need to be the cloud administrator.  This entry is entirely directed to cloud users.  Since Eucalyptus IAM is similar to AWS IAM, the following EC2 Actions need to be allowed for the cloud user:

Instance Deployment

To get started, we need to launch the Ubuntu Raring EMI that has been provided by the cloud administrator.  In this example, the EMI will be emi-26403979:

$ euca-describe-images emi-26403979 --region account1-user01@
IMAGE emi-26403979 ubuntu-raring-docker-rootfs-v3/ubuntu-raring-docker-v3.manifest.xml
 441445882805 available private x86_64 machine eki-17093995 
eri-6BF033EE instance-store paravirtualized

If the –region option seems confusing, this is due to the fact that I am using the nice configuration file feature in Euca2ools.  Its really helpful when you are using different credentials for different users.

Now that we know the EMI we can use, lets launch the instance.  We will be using the cloud-init config file from my previous Docker blog to configure the instance.  The VM type used here is c1.xlarge.  This is because I wanted to make sure I had 2 CPU, and 2 Gigs of RAM for my instance:

$ euca-run-instances -k account1-user01 -t c1.xlarge 
--user-data-file cloud-init-docker.config emi-26403979 
--region account1-user01@
RESERVATION r-2EE941D4 961915002812 default
INSTANCE i-503642D4 emi-26403979
 euca-0-0-0-0.eucalyptus.internal pending account1-user01 0 
c1.xlarge 2014-02-14T00:47:15.632Z LayinDaSmackDown eki-17093995 
eri-6BF033EE monitoring-disabled instance-store paravirtualized

Make sure the instance gets into the running state:

$ euca-describe-instances --region account1-user01@
RESERVATION r-2EE941D4 961915002812 default
INSTANCE i-503642D4 emi-26403979
 euca-172-17-112-207.eucalyptus.internal running 
account1-user01 0 c1.xlarge 2014-02-14T00:47:15.632Z 
LayinDaSmackDown eki-17093995 eri-6BF033EE monitoring-disabled instance-store paravirtualized

Now thats in the running state, lets SSH into the instance to make sure its up and running:

$ ssh -i account1-user01.priv
Welcome to Ubuntu 13.04 (GNU/Linux 3.8.0-33-generic x86_64)
* Documentation:
System information as of Fri Feb 14 00:49:52 UTC 2014
System load: 0.21 Users logged in: 0
 Usage of /: 21.8% of 4.80GB IP address for eth0:
 Memory usage: 5% IP address for lxcbr0:
 Swap usage: 0% IP address for docker0:
 Processes: 85
Graph this data and manage this system at
Get cloud support with Ubuntu Advantage Cloud Guest:

Use Juju to deploy your cloud instances and workloads:

Your Ubuntu release is not supported anymore.
For upgrade information, please visit:

New release '13.10' available.
Run 'do-release-upgrade' to upgrade to it.
Last login: Tue Nov 19 00:48:23 2013 from

Now its time to prepare the instance to create your own base Docker CentOS 6.5 image.

Preparing the Instance

To prepare the instance to create the base image, install the following packages using apt-get:

ubuntu@euca-172-17-112-207:~$ sudo -s
root@euca-172-17-112-207:~# apt-get install rinse perl rpm \
rpm2cpio libwww-perl liblwp-protocol-https-perl

After the packages finish installing, lets go ahead and mount the ephemeral storage on the instance as /tmp to give Docker extra space for building the base image:

root@euca-172-17-112-207:~# curl
root@euca-172-17-112-207:~# mount /dev/vda2 /tmp
root@euca-172-17-112-207:~# df -ah
Filesystem Size Used Avail Use% Mounted on
/dev/vda1 4.8G 1.1G 3.5G 24% /
proc 0 0 0 - /proc
sysfs 0 0 0 - /sys
none 4.0K 0 4.0K 0% /sys/fs/cgroup
none 0 0 0 - /sys/fs/fuse/connections
none 0 0 0 - /sys/kernel/debug
none 0 0 0 - /sys/kernel/security
udev 993M 8.0K 993M 1% /dev
devpts 0 0 0 - /dev/pts
tmpfs 201M 240K 201M 1% /run
none 5.0M 0 5.0M 0% /run/lock
none 1002M 0 1002M 0% /run/shm
none 100M 0 100M 0% /run/user
/dev/vda2 9.4G 150M 8.8G 2% /tmp
root@euca-172-17-112-207:~# lsblk
vda 253:0 0 15G 0 disk
├─vda1 253:1 0 5G 0 part /
├─vda2 253:2 0 9.5G 0 part /tmp
└─vda3 253:3 0 512M 0 part

Next, download the script from the Docker repository on Github:

root@euca-172-17-112-207:~#  wget --no-check-certificate
root@euca-172-17-112-207:~# chmod 755

Now we are ready to build the CentOS 6.5 Base Image.

Building the CentOS Image

The only thing left to do is build the base image.  Use to build the CentOS 6.5 base image:

root@euca-172-17-112-207:~# ./ ubuntu/centos centos-6

After the installation is complete, test out the base image:

root@euca-172-17-112-207:~# docker run ubuntu/centos:6.5 cat /etc/centos-release
CentOS release 6.5 (Final)

Now we have a CentOS 6.5 base image.  The script can also be used to install CentOS 5 base images as well.  Instead of passing centos-6, just pass centos-5.  For example, I have created a CentOS 5 base image in this instance as well.  Below shows the output of the images added to Docker:

root@euca-172-17-112-207:~# docker images
ubuntu/centos 5.10 06019bdea24b 2 minutes ago 123.8 MB
ubuntu/centos 6.5 cd23a8442c8a 2 hours ago 127.3 MB
root@euca-172-17-112-207:~# docker run ubuntu/centos:5.10 cat /etc/redhat-release
CentOS release 5.10 (Final)

As you can see, Docker helps developers test their software across multiple Linux distributions.  With Eucalyptus (just as in AWS), users can use the ephemeral nature of instances to quickly stand up this test environment in one instance.

Step-by-Step Deployment of Docker on Eucalyptus 3.4 for the Cloud Administrator


Eucalyptus Systems, Inc.

Docker has been in the news lately as one of the hot open-source project promoting linux containers. Some use cases for Docker include the following:

  • Automation of packaging and application deployment
  • Lightweight PaaS environments
  • Automated testing and continuous integration/deployment
  • Deploying and scaling web applications, databases and backend services

The focus of this blog entry is to show how to deploy Docker on Eucalyptus from a cloud administrator’s point-of-view – all in the cloud.  This is a step-by-step guide to create an Docker EMI from an existing Ubuntu Cloud Raring EMI using AWS’s documentation.  This entry will also show how to build euca2ools from source in the Ubuntu Cloud image.


This entry assumes the following:

After confirming that the prerequisites are met, let’s get started.

Creating an EMI From an Existing EMI

As mentioned earlier, these steps will be based off of  AWS’s documentation on creating an instance store-backed AMI from an existing AMI.  In this example, here is an existing Ubuntu Raring instance thats running on Eucalyptus:

$ euca-describe-instances --region eucalyptus-admin@
RESERVATION r-3E423E33 961915002812 default
INSTANCE i-827E3E88 emi-06663A57
euca-172-17-118-27.eucalyptus.internal running euca-admin 0 m1.medium 
2013-11-18T22:41:35.694Z LayinDaSmackDown eki-28F338EB eri-51253C0A 
monitoring-disabled instance-store

This instance is using the following EMI, EKI and ERI:

$ euca-describe-images emi-06663A57 eki-28F338EB eri-51253C0A --region eucalyptus-admin@
IMAGE eki-28F338EB latest-raring-kernel/raring-server-cloudimg-amd64-vmlinuz-generic.manifest.xml 
441445882805 available public x86_64 kernel instance-store
IMAGE emi-06663A57 latest-raring/raring-server-cloudimg-amd64.img.manifest.xml 441445882805 
available public x86_64 machine eki-28F338EB eri-51253C0A instance-store paravirtualized
IMAGE eri-51253C0A latest-raring-kernel/raring-server-cloudimg-amd64-loader.manifest.xml 441445882805 
available public x86_64 ramdisk instance-store

To start, copy the zip file cloud administrator credentials obtained by the euca_conf command mentioned in the Eucalyptus 3.4 documentation to the running instance:

# scp -i euca-admin.priv

Next, install the following packages for the 3.8.0-33 kernel, and packages needed to build euca2ools:

ubuntu@euca-172-17-118-27:~$ sudo apt-get install python-setuptools git python-lxml unzip linux-headers-3.8.0-33-generic linux-image-extra-3.8.0-33-generic

Find the ephemeral storage using the instance metadata service, format, and mount the ephemeral to /mnt/image:

ubuntu@euca-172-17-118-27:~$ curl
ubuntu@euca-172-17-118-27:~$ sudo mkdir /mnt/image
ubuntu@euca-172-17-118-27:~$ sudo mkfs.ext4 /dev/vda2
ubuntu@euca-172-17-118-27:~$ sudo mount /dev/vda2 /mnt/image

Download euca2ools from Github:

ubuntu@euca-172-17-118-27:~$ git clone

Install euca2ools:

ubuntu@euca-172-17-118-27:~$ cd euca2ools; sudo python install

Unzip the cloud administrator credentials in /tmp:

ubuntu@euca-172-17-118-27:~$ cd /tmp; unzip

Change to the root user, and source the cloud administrator credentials:

ubuntu@euca-172-17-118-27:~$ sudo -s; source /tmp/eucarc

Bundle, upload and register the ramdisk and kernel under /boot:

root@euca-172-17-118-27:~# euca-bundle-image -i /boot/initrd.img-3.8.0-33-generic 
--ramdisk true -r x86_64
root@euca-172-17-118-27:~# euca-upload-bundle -b ubuntu-raring-docker-ramdisk 
-m /var/tmp/bundle-SQrAuT/initrd.img-3.8.0-33-generic.manifest.xml
root@euca-172-17-118-27:~# euca-register -n ubuntu-raring-docker-ramdisk 
IMAGE eri-6BF033EE
root@euca-172-17-118-27:~# euca-bundle-image -i /boot/vmlinuz-3.8.0-33-generic 
--kernel true -r x86_64
root@euca-172-17-118-27:~# euca-upload-bundle -b ubuntu-raring-docker-kernel 
-m /var/tmp/bundle-31Lnxy/vmlinuz-3.8.0-33-generic.manifest.xml
root@euca-172-17-118-27:~# euca-register -n ubuntu-raring-docker-kernel 
IMAGE eki-17093995

Use euca-bundle-vol to bundle the root filesystem. Make sure to exclude /tmp, /mnt/image, and /home/ubuntu. Additionally, make sure and set the size of the image to be 5 GB:

root@euca-172-17-118-27:~# euca-bundle-vol -p ubuntu-raring-docker 
-s 5120 -e /tmp,/root,/mnt/image,/home/ubuntu -d /mnt/image 
--kernel eki-17093995 --ramdisk eri-6BF033EE -r x86_64

Next, upload and register the root filesystem:

root@euca-172-17-118-27:~# euca-upload-bundle -b ubuntu-raring-docker-rootfs 
-m /mnt/image/ubuntu-raring-docker.manifest.xml
root@euca-172-17-118-27:~# euca-register -n ubuntu-raring-docker-rootfs 
IMAGE emi-26403979

We have the new EMI, EKI and ERI for the Docker instance.  Lastly, set the image permissions so that all users on the cloud can use the EMI, EKI and ERI:

root@euca-172-17-118-27:~# euca-modify-image-attribute -l -a all emi-26403979
root@euca-172-17-118-27:~# euca-modify-image-attribute -l -a all eki-17093995
root@euca-172-17-118-27:~# euca-modify-image-attribute -l -a all eri-6BF033EE

Now its time to launch the Docker EMI.

Running the Docker Instance with Cloud-Init

Before launching the EMI, the cloud-init configuration file needs to be created.  This file will be responsible for configuring the instance repositories, downloading and installing Docker.  With your favorite command-line editor, create a file called cloud-init-docker.config, with the following content:

apt_update: true
apt_upgrade: true
disable_root: true
 - less
 - ssh
 - [ apt-update-upgrade, always ]
 - updates-check
 - runcmd
 - [ sh, -xc, "INST_HOSTNAME=`/bin/hostname`; META_IP=`curl -s`; echo ${META_IP} ${INST_HOSTNAME} >> /etc/hosts" ]
 - [ locale-gen, en_US.UTF-8 ]
 - [ sh, -xc, "wget -qO docker-io.gpg" ]
 - [ apt-key, add, docker-io.gpg ]
 - [ sh, -xc, "echo 'deb docker main' > /etc/apt/sources.list.d/docker.list" ]
 - [ apt-get, update ]
 - [ apt-get, install, -y, --force-yes, lxc-docker ]
 - [ modprobe, -q, aufs ]

Now, use euca-run-instances to launch the instance:

root@euca-172-17-118-27:~# euca-run-instances -k euca-admin emi-351237D1 
-t m1.medium --user-data-file cloud-init-docker.config

After launching the instance, leave the current instance to get back to end client.

root@euca-172-17-118-27:~# exit
ubuntu@euca-172-17-118-27:~$ exit
Connection to closed.

Once the instance reaches running state, ssh into the instance using the keypair specified (which in this case will be euca-admin.priv), and execute the following Docker command to run an interactive shell session inside a minimal Ubuntu container:

$ euca-describe-instances --region eucalyptus-admin@
RESERVATION r-A1613D7F 961915002812 default
INSTANCE i-AFDB3D4C emi-26403979 
euca-172-17-118-16.eucalyptus.internal running euca-admin 0 m1.medium 
2013-11-19T01:21:10.880Z LayinDaSmackDown eki-17093995 eri-6BF033EE monitoring-disabled instance-store
# ssh -i euca-admin.priv
Welcome to Ubuntu 13.04 (GNU/Linux 3.8.0-33-generic x86_64)
* Documentation:
System information as of Thu Nov 14 23:18:38 UTC 2013
System load: 0.0 Users logged in: 0
 Usage of /: 21.6% of 4.89GB IP address for eth0:
 Memory usage: 4% IP address for lxcbr0:
 Swap usage: 0% IP address for docker0:
 Processes: 83
Graph this data and manage this system at
Get cloud support with Ubuntu Advantage Cloud Guest:

Use Juju to deploy your cloud instances and workloads:

New release '13.10' available.
Run 'do-release-upgrade' to upgrade to it.
Last login: Thu Nov 14 23:08:09 2013 from
ubuntu@euca-172-17-184-76:~$ sudo docker run -i -t ubuntu /bin/bash
Unable to find image 'ubuntu' (tag: latest) locally
Pulling repository ubuntu
8dbd9e392a96: Download complete
b750fe79269d: Download complete
27cf78414709: Download complete
root@041d5ddcd6b9:/# (Ctrl-p Ctrl-q to exit out of shell)
ubuntu@euca-172-17-184-76:~$ sudo docker ps
041d5ddcd6b9 ubuntu:12.04 /bin/bash 27 seconds ago Up 26 seconds pink_frog

Thats it!  For more information regarding Docker, please refer to the latest Docker documentation.