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Posts Tagged ‘containers’


October 20th, 2010 by

A matryoshka doll, also known as a Russian nesting doll or a babushka doll, is a set of dolls of decreasing sizes placed one inside the other. A set of matryoshkas consists of a wooden figure which separates, top from bottom, to reveal a smaller figure of the same sort inside, which has, in turn, another figure inside of it, and so on. Matryoshka Doll

Virtualization is a concept similar to the Matryoshka analogy. There is another system running inside the host machine. So it is box in a box. There are many virtualization techniques available at the disposal of the user; vmware, virtualbox, xen to name a few which requires lots of resources. Another alternative which is OpenVZ , container-based virtualization for Linux. Each container performs and executes exactly like a stand-alone server; a container can be rebooted independently and have root access, users, IP addresses, memory, processes, files, applications, system libraries and configuration files.

Here is a quote from TechRepublic Blog :

In the past we have looked at using OpenVZ for container virtualization on Linux. OpenVZ is great as it allows you to run compartmentalized “servers” within an operating system so you can separate systems, much like running virtual machines on a host system. With OpenVZ, you can get the benefits of virtualization without the overhead.

The downside of OpenVZ is that it isn’t in the mainline kernel. This means you need to run a kernel provided by the OpenVZ project. By itself this isn’t necessarily a problem, unless you are running an unsupported Linux distribution, and also if you don’t mind a bit of lag from upstream security fixes

So what is an alternative; well maybe lxc is the answer.According to http://lxc.sourceforge.net/

The  container  technology  is actively being pushed into the mainstream linux kernel. It provides the resource management through the control groups aka process containers and resource isolation through the namespaces.

There is very little information regarding LXC in the opensuse wiki and the only one available is still draft, yet provides enough information to start rolling up your containers.  Here is the preamble of the above mentioned page:

LXC is a form of paravirtualization. Being a sort of super duper chroot jail, it is limited to running linux binaries, but offers essentially native perfomance as if those binaries were running as normal processes right in the host kernel. Which in fact, they are.

LXC is interesting primarily in that:

  • It can be used to run a mere application, service, or a full operating system.
  • It offers essentially native performance. A binary running as an LXC guest is actually running as a normal process directly in the host os kernel just like any other process. In particular this means that cpu and i/o scheduling are a lot more fair and tunable, and you get native disk i/o performance which you can not have with real virtualization (even Xen, even in paravirt mode) This means you can containerize disk i/o heavy database apps. It also means that you can only run binaries that the host kernel can execute. (ie: you can run Linux binaries, not another OS like Solaris or Windows)

The same page also states there is not another HOWTO or documentation explaining how to use lxc with opensuse even though the lxc package has been part of the main oss repo since 11.2 version. Furthermore there are no scripts like lxc-fedora or lxc-debian  that will automate the creation or installation of opensuse. Now while it may be true that there are no opensuse specific scripts are available (at least I could not find through a Google search), though there is an interesting video on youtube showing the lxc with opensuse 11.2.

Based on the the information on the LXC wiki page, using the  SUSEStudio , I built an appliance which  is almost ready to use lxc. In order to create a container image, a very primitive lxc_opensuse script that will do a fairly basic job is also included. Once the script is issued,it will download opensuse 11.3 base system and the user can start playing with the wonders of lxc. For the impatient, who wants do discover Matryoshka, here is the link for  the appliance .

Have fun with Matryoshka !