Even though Linux operating systems have very low minimum hardware requirements anyway, there's always room to get even leaner, or just enough.
SUSE Linux Enterprise JeOS (pronounced "juice"), the beta "Just enough" operating system from Novell, is a lightweight and bare-bones version of the company's SUSE Linux Enterprise Server. The code base is SLES 10 Service Pack 2. The stripped-down operating system is intended specifically for virtual appliances. Applications certified to run on SUSE Linux Enterprise Server will carry that certification onto the JeOS platform as well.
By ripping out general purpose software, such as graphical desktops, word processing applications, and media packages, the resulting base OS is smaller and much more efficient: two pluses when working in the virtual environment. Yes, it's possible to sit down and rip out unwanted components from the standard OS, but it's always easier to build up from the absolute minimum and adding additional packages from SUSE Linux Enterprise Server, than it is to go the other way. Even using application repositories, such as rPath's rBuilder product which automates the process of customizing the OS for an appliance, can involve some fiddling. SUSE JeOS is pre-tested and removes a lot of the guesswork.
Novell's SUSE Appliance Program targets ISVs interested in deploying integrated packages with SUSE Linux Enterprise. Under the program, the partner can create appliances using both the SLES and SUSE JeOS platforms. It's up to the ISV to decide which type of SUSE to use. These bundles simplify application support, reduce development costs, and ease customer deployment. Creating an appliance is a way for solution providers to source their own hardware and install the software application before selling to the customer. It's particularly an attractive option for open-source software. Test Center reviewers have flagged appliances (both virtual and physical) as a potential revenue opportunity for several products.
At the moment, the SUSE JeOS beta is available as a pre-installed, ready-to-run virtual machine image in any VMware application " VMware Workstation, VMware Server, and VMware Player " as well as on Citrix Systems' Xen Server. Novell plans to release a version for Microsoft's Hyper-V later this year. A production version is scheduled for release later this year.
The VMware file is only 267 Mbytes in size " significantly smaller than what a SLES install on Vmware would be.
Getting started on JeOS was fairly simple. Reviewers downloaded the VMware package and obtained an activation code from Novell's web site. The virtual machine file was opened using VMware Server. When the virtual machine is powered on, it doesn't load a graphical interface like SUSE does " it merely checks and loads a handful of hardware packages, such as detecting a network controller and configuring the network interface. Once the ten or so components have been configured, the user is prompted to login at the command line. After logging in as root, the operating system was registered with Novell in order to access the entire library of SLES packages for installation. Running zypper, the package installer, shows that all of the packages are available, such as SuSEFirewall2, Mozilla Firefox, python, apache, and postgreSQL.
At this point, JeOS has pretty much nothing installed other than what its core system requires to start up. If the virtual appliance needs a web server, the ISV can install Apache. The JeOS platform bucks the general trend toward automation and a one-size-fits-all approach. This is a very manual approach, installing and configuring the components to get the perfect operating system. Novell has said it will eventually introduce automated tools under the Appliance Program.
The JeOS kit comes with a supportability analysis tool to examine any changes made to the stack. Partners can look at the tool to figure out if the configuration they created is supportable.
Reviewers created their own virtual appliance " for Epiware, an open-source collaboration tool - for this review. Epiware is a Web application featuring a calendar, a built-in wiki, support for a Gantt Chart (project management), and a document repository. Reviewers installed PHP, MySQL, and Apache using zypper. After that, it was a simple matter to download Epiware and make the appropriate configuration changes. At this point, the reviewers shut down the VM and copied the file to a different machine. The VM started without a problem and the Epiware site was good to go. This is not a perfect test, since this particular VM file can't be distributed widely " the configuration settings are unique to the Test Center network. However, it does highlight how simple it can be to create a lightweight appliance using SUSE JeOS. All the ISV really has to do is to put in an installer script that writes the customer-specific data to the configuration file, and deployment becomes a task that takes a handful of minutes.
This wouldn't be Linux if there wasn't a community-based version. Named LimeJeOS, this is a variant of openSUSE.
SUSE is not the first Linux flavor to join the appliance and JeOS party " Canonical launched Ubuntu JeOS and Red Hat expects to have an Appliance Operating System in beta mid-year. That said, Novell has the channel presence and well-defined support packages to make the shift to SUSE-based virtual appliances a possibility.