User manual: vmcasts

What are VMCasts ?

In one word, it's a RSS feed that proposes some links to download xvm2 files. xvm2 is a simple tar containing:

• GZIP image of drives, one gzip per drive
• a MANIFEST
• a file named description.xml containing the actual libvirt domain description

An example of VMCast would be:

<?xml version="1.0" encoding="utf-8"?><rss version="2.0">
<channel>
  <title>My Awesome VMCast</title>
  <link>http://www.archipelproject.org</link>
  <uuid>ec53db38-a692-4f04-bac9-50ff9f590001</uuid>
  
  <description>The awesome VMCast feed for Archipel</description>
  <language>en-us</language>
    <item>
        <title>Wordpress template</title>
        <link>http://www.archipelproject.org</link>
        <uuid>ae201436-8b36-11dd-bbb3-269650d01a85</uuid>
        <enclosure url="http://myhypervisor/wordpresstemplate.xvm2" length="266741760" type="application/enomalism2-xvm2"/>
        <description>Debian with Wordpress ready to use</description>
	<pubDate>Tue, 23 Sep 2011 12:00:00 -0800</pubDate>
    </item>
    ....
    <item>
        <title>Windows XP</title>
        <link>http://www.archipelproject.org</link>
        <uuid>ae201436-8b36-11dd-bbb3-269650d01a86</uuid>
        <enclosure url="http://myhypervisor/wordpresstemplate.xvm2" length="42000000" type="application/enomalism2-xvm2"/>
        <description>Windows XP virtual machines</description>
	<pubDate>Tue, 23 Sep 2011 12:00:00 -0800</pubDate>
    </item>
</channel>
</rss>

Archipel understands VMCasts, and you can register to any available VMCasts over the internet. Each hypervisor can package existing virtual machines into xvm2 appliances and can generate a valid VMCast repository and the RSS file containing informations about it.

Prepare the platform

Folder informations

Each hypervisors contains two folders that are related for VMCasts and appliances:

• /vm/repo: It contains all the downloaded and ready to use appliances from random VMCasts
• /vm/vmcast: It contains all the appliances that are published in hypervisor's VMCast and the rss.xml file

Install web server

Archipel generates automatically everything to use the VMCasts. But it's up to you to serve the feed. You just need a simple HTTP server. We will use nginx for this purpose.

First, install nginx:

yum install nginx

Then open /etc/nginx/nginx.conf, locate the default server and edit it:

http {
    ...
    # The default server
    #
    server {
        listen       8080; # beware if you already have a http server running on port 80!
        server_name  _;
        location / {
            root   /vm/vmcasts/;
            index  rss.xml;
        }
    }
}

Then start nginx:

service nginx start

Now, let's say your nginx is accessible from the outside with url http://vmcast.hypervisor.com:8080/

Update archipel configuration

Edit /etc/archipel/archipel.conf and locate the [VMCASTING] section (note that only the own_vmcast_url parameter needs to be updated):

[VMCASTING]

...

# the name of vmcast. $HOSTNAME is replaced by the actual hostname
own_vmcast_name             = Local VM casts of $HOSTAME

# vmcast description
own_vmcast_description      = This is the own vmcast feed of the hypervisor $HOSTAME

# the url to access the vmcast
## THIS IS CAPITAL TO ADD THE BASE URL YOU CONFIGURE WITH YOUR HTTP SERVER!
own_vmcast_url              = http://vmcast.hypervisor.com:8080/

...

And finally, restart archipel agent

/etc/init.d/archipel restart

Your platform is now ready to use VMCasts and publish appliances!

Using VMCasts

Register to your hypervisor VMCasts

You need to make your hypervisor to register to its own VMCasts (it's not necessary if you don't plan to use its own templates, but in this example, we have only one hypervisor). So first of all, select your hypervisor from the contact list, then select the VMCast module.

Then click the + button to register to a new VMCast feed, and enter the URL we configure in previous section (http://vmcast.hypervisor.com:8080/):

Click Register. You will see the list of available appliances after a little while:

As you can see, it's empty. That's normal as we haven't created any appliances. Let's do this.

Create a new appliance

To do so, create a new virtual machine using the normal way (or use an existing one). Then configure it as you want. Install what you want on it, configure it as you like. When you will be happy with it, package it. To do so, choose the Appliances module of your Virtual Machine, and click on the Package button (it looks like a small box):

Choose a name (it cannot be changed! choose wisely) and click on Package button. The virtual machine will become in "Do Not Disturb" (DND) mode. Wait for the packaging to finish.

Note it can be pretty long, depending on how much drive you have, their size etc.

When packaging is done, virtual machine becomes available again. The appliance has been published in your hypervisor VMCast:

The size is 0KB simply because we create an empty drive for the purpose of this tutorial.

Install appliances

You need to install appliance in order to use them (even if it's from the own hypervisor VMCasts. We'll talk about this later). To download an appliance, select it, and click on the down arrow icon (or simply double click on it):

Confirm you want to download the appliance. Then a download manager appears and give you the download status. Download is obviously done in background by the agent, you can continue to use Archipel. When appliance is downloaded, you will see the green pill indicating it's available. You can now use it for any virtual machines running on the hypervisor.

Use appliances

Create a new VM, or choose an existing one (note that if you use an appliance on an already configured virtual machine you will loose all existing data!). Go to virtual machines Appliances module. Your template will be listed:

To use it, just click the attach button (looks like a lock), or double click on it:

Confirm and wait. Virtual machine will enter in "DND" mode during the decompression of the informations. Description will be updated, new MAC address will be generated etc. After a while, the VM becomes available again, and you have a brand new VM based on your template.