Build Your Own Cloud with Eucalyptus

Got lots of systems? Make them into a cloud computing cluster with Eucalyptus!
Installing Images on Your UEC

Although it's possible to make your own custom images to run on your cloud (see Resources for a link on bundling images), it's far easier to get one from the UEC “store” (Figure 2). Simply access the cloud controller at the URL https://<cloud-controller-ip-address>:8443/, enter your login and password, click the Store tab, and you'll be presented with the UEC Store. Just find an image you'd like to install (at the time of this writing, there are only three), and push the Install button. Your image will download and install to your cluster automagically. Once that's done, you'll get a How to Run? link under the grayed-out Install button. If you click that link, you'll get the exact command line that will instantiate, or start, your selected image.

Figure 2. UEC Store

Starting Your Image

Instantiating an image requires you to use the command line on the cloud controller (or wherever you installed your credentials). Before you run your first image, you've got to create an SSH keypair so you can log in to your instance as root once it's up and running. The key is stored and is common across all your instances, so this script needs to be run only once:

if [ ! -e ~/.euca/mykey.priv ]; then
    touch ~/.euca/mykey.priv
    chmod 0600 ~/.euca/mykey.priv
    euca-add-keypair mykey > ~/.euca/mykey.priv
fi

Next, configure the cloud to allow port 22 access (SSH) inbound for all instances. The following command will allow SSH from any source IP:

euca-authorize default -P tcp -p 22 -s 0.0.0.0/0

Now, you can fire up your first image:

bill@falcon:~$ euca-run-instances emi-DF841070 -k mykey -t c1.medium
RESERVATION     r-3409079E      admin   admin-default
INSTANCE        i-46780864      emi-DF841070
                                    0.0.0.0  0.0.0.0  pending mykey
                                    2009-12-10T06:26:09.471Z
                                    eki-F59010E3  eri-0A2A115C

The first time you instantiate a particular image, it'll be slow to start. Eucalyptus caches the image on the node controller, so there's a sizable amount of data that's got to move to the node. You can keep tabs on the status of your image by running:

watch -n5 euca-describe-instances

You'll see two IP addresses listed in the output of the euca-describe-instances command. One will be an IP on your LAN, and the other will be a private IP. Once the instance is listed as “running”, you can ssh to it on the IP listed in the output. Note that it doesn't have a user account with a password on it, so you need to use the SSH key created earlier:

bill@falcon:~$ euca-describe-instances
RESERVATION     r-3409079E      admin   default
INSTANCE        i-46780864      emi-DF841070
                                    192.168.1.170  172.19.1.2
                                    running  mykey  0  c1.medium
                                    2009-12-10T06:26:09.471Z
                                    cluster1
                                    eki-F59010E3  eri-0A2A115C
bill@falcon:~$
bill@falcon:~$ ssh -i ~/.euca/mykey.priv ubuntu@192.168.1.170
The authenticity of host '192.168.1.170' can't be established.
...
Are you sure you want to continue connecting (yes/no)? yes
...
Linux 172 2.6.31-14-server #48-Ubuntu SMP Fri Oct 16 15:07:34 
UTC 2009 x86_64

...

  System information as of Thu Dec 10 06:32:03 UTC 2009

  System load: 0.0              Memory usage: 16%  Processes:      70
  Usage of /:  29.6% of 1.98GB  Swap usage:   0%   Users logged in: 0

...
ubuntu@172:~$

At this point, you're in your instance, and it's a fully functioning system. You can apt-get packages like apache or do further system configuration if you want. When you're done, you can exit your SSH session, and then terminate the instance by finding the instance ID from the output of the euca-describe-instances command (in the example above, it's i-46780864) and running euca-terminate-instances <instanceID>. Your instance will then shut down.

This article barely scratches the surface of what's possible with the Ubuntu Enterprise Cloud. Although it's less flexible than other virtualization technologies like VMware or VirtualBox, it is API-compatible with Amazon's EC2 service, and it allows you to build networks of virtual machines far beyond what's possible with conventional virtualization solutions. If you require a scalable network of virtual systems that can be instantiated and terminated dynamically, the Ubuntu Enterprise Cloud and Eucalyptus are for you.

______________________

Bill Childers is the Virtual Editor for Linux Journal. No one really knows what that means.

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