A quick tour of Cloudstack

Cloud.com, now a part of Citrix, has developed a neat, compact, yet powerful platform for cloud management: Enter cloudstack, a provisioning, management and automation platform for KVM, Xen and VMware, already trusted for private and public cloud management frmo companies like Zynga (got Farmville?), Tata communications (public IaaS) and KT (major Korean Service provider).

Recently I had the chance to give cloudstack a spin in a small lab installation with one NFS repository and two Xenservers. Interested in how it breathes and hums? Read on, then.

Cloudstack was installed in a little VM in our production vSphere environment. Although it does support vSphere 4.1, we decided to try it with Xen and keep it off the production ESX servers. Installation was completed in 5 minutes (including the provisioning of the Ubuntu 10.04 server from a ready VMware tremplate) and cloudstack came to life, waiting for us to login:

The entire interface is AJAX – no local client. In fact, cloudstack can be deployed in a really small scale (a standalone server) or in a full-blown fashion, with redundant application and database servers to fulfill scalability and availability policies.

Configuring cloudstack is a somewhat more lengthy process and requires reading the admin guide. We decided to follow the simple networking paradigm, without VLANs and use NFS storage for simplicity. Then, it was time to define zones, pods and clusters, primary and secondary storage. In a nutshell:

  • A zone is a datacenter. A zone has a distinct secondary storage, used to store boot ISO images and preconfigured virtual machine templates.
  • A pod is servers and storage inside a zone, sharing the same network segments
  • A cluster is a group of servers with identical CPUs (to allow VM migration) inside a pod. Clusters share the same primary storage.
We created a single zone (test zone) with one pod and two clusters, each cluster consisting of a single PC (one CPU, 8 GB RAM) running Xenserver 5.6. Configuring two clusters was mandatory, since the two Xenservers were of different architectures (Core 2 and Xeon). After the configuration was finished, logging in to Cloudstack as administrator brings us to the dashboard.

In a neat window, the datacenter status is shown in clear, with events and status in the same frame. From here an administrator has full power over the entire deployment. This is a host (processing node in Openstack terms) view:

You can see the zone hierarchy in the left pane and the virtual machines (instances) running on the host shown in the pane on the right.

Pretty much, what an administrator can do is more or less what Xencenter and vCenter do: Create networks, virtual machine templates, configure hosts and so on. Let’s see how the cloudstack templates look like:

Cloudstack comes with some sample templates and internal system virtual machine templates. These are used internally, but more on them later. The administrator is free to upload templates for all three hypervisor clans (KVM, Xen and Vcenter). For KVM, qemu images, for VMware, .ova and for Xenserver VHD. We created one Windows 2008 server template quite easily, by creating a new VM in Xencenter, installing Xentools and then uploading the VHD file in Cloudstack:

As soon as the VHD upload is finished, it is stored internally in the Zone secondary storage area and is ready to be used by users (or customers).

How does cloudstack look like from the user/customer side? We created a customer account (Innova) and delegated access to our test zone:

Customers (depending on their wallet…) have access to one or more pods and can create virtual machines freely, either from templates of from ISO boot images they have access to, without bringing into the loop cloudstack administrators. Creating a new virtual machine (instance) is done through a wizard. First, select your favorite template:

Then, select a service offering from preconfigured sizes (looks similar to EC2?)

Then, select a virtual disk. A template comes with its own disk (in our case the VHD we uploaded earlier), but you can add more disks to your instances. This can also be done after the instance is deployed.

…and after configuring the network (step 4), you are good to go:

The template will be cloned to your new instance, boot up, and form this point on, you can log in through the web browser – no RDP or VNC client needed!

It’s kind of magic — doing this via an app server seems impossible, right? Correct. Cloudstack deploys silently and automagically its own system VMs that take care of template deployment to computing nodes and storage. Three special kinds of VMs are used:

  • Console proxies that relay to a web browser VNC, KVM console or RDP sessions of instances. One console proxy runs in every zone.
  • Secondary storage VM, that takes care of template provisioning
  • Virtual router, one for every domain (that is, customers), which supplies instances with DNS services, DHCP addressing and firewalling.
Through the virtual router users can add custom firewall rules, like this:
All these system virtual machines are managed directly from cloudstack. Login is not permitted and they are restarted upon failure. This was demonstrated during an unexpected Xenserver crash, which brought down the zone secondary storage VM. After the Xenserver was booted up, the secondary storage VM was restarted automatically by cloudstack and relevant messages showed up in the dashboard. Cool, huh?

Customers have full power over their instances, for example, they can directly interact with virtual disks (volumes), including creating snapshots:

In all, from our little cloudstack deployment we were really impressed. The platform is very solid, all advertised features do work (VM provisioning, management, user creation and delegation, templates, ISO booting, VM consoles, networking) and the required resources are literally peanuts: It is open source and all you need are L2 switches (if you go with basic networking), servers and some NFS storage. Service providers investigating options for their production IaaS platform definitely should look into cloud.com offerings, which has been a part of Citrix since July 2011.


11 responses to “A quick tour of Cloudstack

  1. Hi thanks for detailed article about your experience. Could you please share the RAM and CPU that you used on the VM to install cloudstack.

    • 4 GB of vRAM and 2 vCPUs (on vSphere 4). It’s not a big deal, once you have cloudstack on a virtual server you can adjust mem and CPU according to your workload. I used stock Ubuntu 10.04 server (barebones, no gnome and stuff).

      • Thanks! One more quick one which I should have asked in the question above.

        What version of Cloudstack did you use? If possible could you please add the link to it.


  2. If I recall correctly (vacation mode right now…) it was 2.2.7. Anyway, the current release is here: http://sourceforge.net/projects/cloudstack/files/Cloudstack%202.2/2.2.8/CloudStack-oss-2.2.8-ubuntu10.04.tar.gz/download

    That’s the Ubuntu release I used, there are RH/CentOS packages as well here: http://cloudstack.org/download.html

    Be aware, take your time first and carefully read the admin documentation here: http://download.cloud.com/releases/2.2.0/CloudStack2.2.4AdminGuide.pdf

  3. Thanks for the article. Got me interested in setting up my own Cloudstack test network and yes, its really great! The HA with the xenservers works like a champ. For anyone getting ready to try it be aware it takes some time to wrap you head around what its doing and you have to be patient. Rebuilt mine several times before I got it right.

  4. How do you install the agent on Xenserver? I used the cloudstack appliance.

    • AFAIK there is no agent for XenServer. You just specify the XenServer management IP address and root password; the rest is done via the API. There is an agent for KVM hosts, though.

  5. Can you please release video tutorial for complete step by step cloudstack installation?

    • Sorry, no time for that… Feel free to ask questions, though. Currently I’m busy with other tools like Abiquo, hopefully I’ll post about the latter early next year.

  6. hi,
    how did you do for your XenServer? CloudStack my environment running under VM completely and I have problems with my xen. the vm does not ping the management server and gw. Have you had this problem?
    (sorry for my langage, I’m french)

    • Hi Marie,

      My installation was with all Xen/KVM hypervisors on physical machines; I did not try at all encapsulating XenServers in VMs. Probably there’s something fishy with vswitches and the way XenServer sends packets. Try with your XenServers on physical hosts; a simple PC or laptop would do the job.

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