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.

Prerequisites

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 http://beta.release.core-os.net/amd64-usr/current/coreos_production_openstack_image.img.bz2

# 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 0.0.0.0/0

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:

#cloud-config
coreos:
 units:
 - name: format-ephemeral.service
 command: start
 content: |
 [Unit]
 Description=Formats the ephemeral drive
 [Service]
 Type=oneshot
 RemainAfterExit=yes
 ExecStart=/usr/sbin/wipefs -f /dev/vdb
 ExecStart=/usr/sbin/mkfs.btrfs -f /dev/vdb
 - name: var-lib-docker.mount
 command: start
 content: |
 [Unit]
 Description=Mount ephemeral to /var/lib/docker
 Requires=format-ephemeral.service
 Before=docker.service
 [Mount]
 What=/dev/vdb
 Where=/var/lib/docker
 Type=btrfs

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 0.0.0.0 0.0.0.0 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-10-104-6-236.bigboi.acme.eucalyptus-systems.com euca-172-18-238-171.bigboi.internal running coreos 0 c1.medium 2014-06-12T13:38:31.008Z ViciousLiesAndDangerousRumors monitoring-disabled 10.104.6.236 172.18.238.17 instance-store hvm sg-A5133B59
# ssh -i coreos.priv core@euca-10-104-6-236.bigboi.acme.eucalyptus-systems.com
CoreOS (beta)
core@localhost ~ $ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
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.

Enjoy!

Making FileVault Use a Disk Password

hspencer77:

Great use of FileVault on Mac OS X.

Originally posted on /dev/zero:

To unlock a disk that is encrypted with OS X’s FileVault feature one needs to type in the password that belongs to any user on the machine who is allowed to unlock the disk. The system then boots and helpfully logs you in as that user. In general that is probably a convenient little feature, but for me it just makes things awkward — I want to use different passwords for unlocking the disk and logging into my user account. To make that work I have to create a second account dedicated to unlocking the disk, get logged into that one when the system boots, then immediately log back out so I can log in as the user I actually want to use.

Or do I?

The system that powers FileVault, Core Storage, combines full disk encryption and some logical volume management features in a manner similar to LVM…

View original 1,170 more words

Install Eucalyptus 4.0 Using Motherbrain and Chef

hspencer77:

Great blog discussing how to use Motherbrain, Chef and Eucalyptus.

Originally posted on Testing Clouds at 128bpm:

Introduction

Installing distributed systems can be a tedious and time consuming process. Luckily there are many solutions for distributed configuration management available to the open source community. Over the past few months, I have been working on the Eucalyptus cookbook which allows for standardized deployments of Eucalyptus using Chef. This functionality has already been implemented in MicroQA using individual calls to Knife (the Chef command line interface) for each machine in the deployment. Orchestration of the deployment is rather static and thus only 3 topologies have been implemented as part of the deployment tab

Last month, Riot Games released Motherbrain, their orchestration framework that allows flexible, repeatable, and scalable deployment of multi-tiered applications. Their approach to the deployment roll out problem is simple and understandable. You configure manifests that define how your application components are split up then define the order in which they should be deployed.

For…

View original 508 more words

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 http://www.vagrantup.com/. (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 https://github.com/hspencer77/eucalyptus-docker-raring.git

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>"
AWS_INSTANCE_TYPE = '<VM type>'
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.

Prerequisites

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.euca-hasp.eucalyptus-systems.com
 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 0.0.0.0 0.0.0.0 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-10-104-7-10.eucalyptus.euca-hasp.eucalyptus-systems.com
 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 
10.104.7.10 172.17.112.207 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 ubuntu@euca-10-104-7-10.eucalyptus.euca-hasp.eucalyptus-systems.com
Welcome to Ubuntu 13.04 (GNU/Linux 3.8.0-33-generic x86_64)
* Documentation: https://help.ubuntu.com/
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: 172.17.112.207
 Memory usage: 5% IP address for lxcbr0: 10.0.3.1
 Swap usage: 0% IP address for docker0: 10.42.42.1
 Processes: 85
Graph this data and manage this system at https://landscape.canonical.com/
Get cloud support with Ubuntu Advantage Cloud Guest:

http://www.ubuntu.com/business/services/cloud

Use Juju to deploy your cloud instances and workloads:

https://juju.ubuntu.com/#cloud-raring

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

http://www.ubuntu.com/releaseendoflife

New release '13.10' available.
Run 'do-release-upgrade' to upgrade to it.
Last login: Tue Nov 19 00:48:23 2013 from odc-d-06-07.prc.eucalyptus-systems.com
ubuntu@euca-172-17-112-207:~$

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 http://169.254.169.254/latest/meta-data/block-device-mapping/ephemeral0
sda2
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
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
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 mkimage-rinse.sh script from the Docker repository on Github:

root@euca-172-17-112-207:~#  wget --no-check-certificate https://raw.github.com/dotcloud/docker/master/contrib/mkimage-rinse.sh
root@euca-172-17-112-207:~# chmod 755 mkimage-rinse.sh

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 mkimage-rinse.sh to build the CentOS 6.5 base image:

root@euca-172-17-112-207:~# ./mkimage-rinse.sh 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 mkimage-rinse.sh 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
REPOSITORY TAG IMAGE ID CREATED VIRTUAL SIZE
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.

12 Steps To EBS-Backed EMI Bliss on Eucalyptus

In previous posts, I shared how to use Ubuntu Cloud Images and eustore with Eucalyptus and AWS.  This blog entry will focus on how to use these assets to create EBS-backed EMIs in 12 steps.   These steps can be used on AWS as well, but instead of creating an instance store-backed AMI first, Ubuntu has already provided AMIs that can be used as the building block instance on AWS.  Let’s get started.

Prerequisites

On Eucalyptus and AWS, it is required the user has the appropriate IAM policy in order to perform these steps.  The policy should contain the following EC2 Actions at a minimum:

  • RunInstances
  • AttachVolume
  • AuthorizeSecurityGroupEgress
  • AuthorizeSecurityGroupIngress
  • CreateKeyPair
  • CreateSnapshot
  • CreateVolume
  • DescribeImages
  • DescribeInstances
  • DescribeInstanceStatus
  • DescribeSnapshots
  • DetachVolume
  • RegisterImage

In addition, the user needs an access key ID and secret key.  For more information, check out the following resources:

This entry also assumes Eucalyptus euca2ools are installed on the client machine.

The 12 Steps

Although the Ubuntu Cloud Image used in this entry is Ubuntu Precise (12.04) LTS, any of of the maintained Ubuntu Cloud images can be used.

  1. Use wget to download tar-gzipped precise-server-cloudimg:
    $ wget http://cloud-images.ubuntu.com/precise/current/precise-server-cloudimg-amd64.tar.gz
  2. After setting the EC2_ACCESS_KEY, EC2_SECRET_KEY, and EC2_URL, use eustore-install-image to an instance stored-backed EMI:
    $ eustore-install-image -t precise-server-cloudimg-amd64.tar.gz \
    -b ubuntu-latest-precise-x86_64 --hypervisor universal \
    -s "Ubuntu Cloud Image - Precise Pangolin - 12.04 LTS"
  3. Create a keypair using euca-create-keypair, then use euca-run-instances to launch an instance from the EMI returned from eustore-install-image. For example:
    $ euca-run-instances -t m1.medium \
    -k account1-user01 emi-5C8C3909
  4. Use euca-create-volume to create a volume based upon the size of how big you want the root filesystem to be.  The availability zone (-z option) will be based on if you are using Eucalyptus or AWS:
    $ euca-create-volume -s 6 \
    -z LayinDaSmackDown
  5. Using euca-attach-volume, attach the resulting volume to the running instance. For example:
    $ euca-attach-volume -d /dev/vdd \
    -i i-839E3FB0 vol-B5863B3B
  6. Use euca-authorize to open SSH access to the instance, SSH into the instance, then use wget to download the Ubuntu Precise Cloud Image (qcow2 format):
    $ ssh -i account1-user01.priv ubuntu@euca-10-104-7-10.eucalyptus.euca-hasp.eucalyptus-systems.com
    # sudo -s
    # wget http://cloud-images.ubuntu.com/precise/current/precise-server-cloudimg-amd64-disk1.img
  7. Install qemu-utils:
    # apt-get install -y qemu-utils
  8. Use qemu-img to convert image from qcow2 to raw:
    # qemu-img convert \
    -O raw precise-server-cloudimg-amd64-disk1.img precise-server-cloudimg-amd64-disk1-raw.img
  9. dd raw image to block device where volume is attached (use dmesg to figure that out easily):
    # dmesg | tail
    [ 7026.943212] virtio-pci 0000:00:05.0: using default PCI settings
    [ 7026.943249] pci 0000:00:07.0: no hotplug settings from platform
    [ 7026.943251] pci 0000:00:07.0: using default PCI settings
    [ 7026.945964] virtio-pci 0000:00:07.0: enabling device (0000 -> 0003)
    [ 7026.955143] virtio-pci 0000:00:07.0: PCI INT A -> Link[LNKC] -> GSI 10 (level, high) -> IRQ 10
    [ 7026.955180] virtio-pci 0000:00:07.0: setting latency timer to 64
    [ 7026.955429] virtio-pci 0000:00:07.0: irq 45 for MSI/MSI-X
    [ 7026.955456] virtio-pci 0000:00:07.0: irq 46 for MSI/MSI-X
    [ 7026.986990] vdb: unknown partition table
    [10447.093426] virtio-pci 0000:00:07.0: PCI INT A disabled
    # dd if=/mnt/precise-server-cloudimg-amd64-disk1-raw.img of=/dev/vdb bs=1M
  10. Log out the instance, and use euca-detach-volume to detach the volume:
    $ euca-detach-volume vol-B5863B3B
  11. Use euca-create-snapshot to create a snapshot of the volume:
    $ euca-create-snapshot vol-B5863B3B
  12. Use euca-register to register the resulting snapshot to create the EBS-backed EMI:
    $ euca-register --name ebs-precise-x86_64-sda \
    --snapshot snap-EFDB40A1 --root-device-name /dev/sda

Thats it!  You have successfully created an EBS-backed EMI/AMI.  As mentioned earlier, these steps can be used on AWS just as well (just skip steps 1 & 2, and use one of the Ubuntu Cloud Images in the AWS region of your choice).  Enjoy!