SUSE Studio for Linux appliances

At the end of July, Novell launched SUSE Studio, which it calls a "simple and fast appliance builder". It provides a free and easy-to-use, web-based user interface to roll your own customized (SUSE) Linux distribution. The resulting image can be deployed on bare metal or as a virtual appliance on a hypervisor. Novell has also started a SUSE Appliance Program to support independent software vendors creating Linux-based software appliances.

First, why would one build such a "software appliance" with SUSE Studio? For companies, the advantages are obvious: an appliance tailored to a specific application set makes it easier to maintain and gives it a more predictable behavior. These companies can distribute one integrated package with the operating system and (server) software to their customers. But the same advantages hold for people who want to build a custom Linux distribution to distribute for free, who want do demo some application during a tradeshow, or who want a distribution with their own branding. SUSE Studio developer Cornelius Schumacher lists some concrete use cases:

SUSE Studio is in beta phase and the website says it's "currently available for a limited number of users", but anyone who sends their email address via the SUSE Studio login page will be put on the invitation list. Kindly asking one of the operators in the #susestudio IRC channel for an invite tends to work too, as your author found out. After receiving login information, signing in can be done with with OpenID among other options. SUSE Studio works in Firefox 2 and 3 on Linux, Mac OS X and Windows, and in Safari 3 on Mac OS X.

From template to installable image

After the first login, the system offers some templates to build the appliance upon. For the base system, the website gives the choice among openSUSE 11.1, SUSE Linux Enterprise 10 and SUSE Linux Enterprise 11. There are templates for JeOS (Just enough OS, a minimalist server appliance), Server, GNOME Desktop, KDE 3 or 4 Desktop, and Minimal X. The last one, which uses the IceWM window manager, is especially useful for making a kiosk-like application. There is also a choice between 32 or 64-bit architectures and a text box to give the appliance a descriptive name.

The user navigates through the rest of the steps by clicking on some tabs. In the Software tab, one can add or remove packages and repositories or upload their own rpm files. Some basic knowledge of the available repositories and software packages is needed, but the interface has a helpful search function. SUSE Studio is also integrated well with the openSUSE Build Service (which enables users to create packages for various Linux distributions from source). One can build packages in the openSUSE Build Service, import the repository into SUSE Studio and use the freshly built packages. For example, this makes it possible to create an openSUSE distribution with KDE 4.3, although by default KDE 4.1 is installed.

The "Configure" tab gives a slew of options to configure: locale settings, timezone, network, firewall, users and groups, the look and feel, the default runlevel, a custom license agreement, MySQL configuration, custom boot scripts, and so on. In the "Overlay files" tab one can add overlay files, if, for example, some custom scripts are needed or some configuration files in /etc have to be changed. Clicking on the "Build" tab gives the choice among a disk image, a live cd, a VMware image, or a Xen image. Support for creating images in OVF (Open Virtualization Format, an open standard for packaging and distributing virtual appliances), Microsoft's Hyper-V, and Amazon's EC2 AMI format (including deployment to EC2) is planned. The build process itself takes less than five minutes most of the time, even for a complete desktop system. The result can then be downloaded.

By looking at some details, one can see that SUSE Studio is well-engineered and has undergone a lot of usability tweaking. For example, in the "Software" tab there's a "Recommended" list of applications, which is different depending on the template the user has chosen. Moreover, at any time the current disk footprint of the appliance is shown at the left side of the web page, which is useful while building an image which has to fit on a CD or a USB thumb drive. The left side also shows helpful messages and tips. For example, while building a VMware image, it suggests installing the open-vm-tools package. And, after adding a package, one can view more details about the package, such as which dependencies are installed. If the firewall is enabled in the "Configuration" tab and it is not installed (for example while building upon a JeOS template), then an error message appears with a button to add SuSEfirewall2. There are a lot of these tips, which seem to come from the developers' experiences and feedback by users of the alpha version.

An appliance in your browser

One great feature is the SUSE Studio Testdrive. This allows the user to boot and test their appliance in a browser window without the need to download it first. After the build, clicking on the Testdrive button will launch the virtual machine. This runs on a KVM hypervisor on Novell's servers and exposes the virtual machine framebuffer via VNC to a Flash applet running in the user's browser. There are even buttons to switch to a different virtual console, to press ctrl-alt-del, to press ctrl-alt-backspace, or to change the keyboard layout. Each Testdrive instance gets 512 MB of RAM and an hour to run.

One can also make changes to files in Testdrive, investigate the diffs, and commit those changes to the appliance. The changes will then be implemented when starting a new build. This is really nice, as one can, for example, fire up an interactive installer of an application and commit the changes, so that appliance users don't have to. SUSE Studio creator Nat Friedman explains in his blog how this is implemented with a copy-on-write (COW) disk image for the KVM image. The original image is only used for reading and all writes go to the COW file. Whenever the virtual machine wants to read a block, it first checks for its presence in the COW file, and falls back to the read-only image if not:

Many possibilities

The SUSE Studio website is a closed-source Ruby on Rails web application, but there are plans to open up the code sometime in the future. Later this year, companies can buy SUSE Studio Onsite, which is a version on a server hosted within their own data center. SUSE Studio uses the open source Kiwi build tool as its backend. When the user has created an appliance with SUSE Studio, he can download the appliance description from SUSE Studio and build the appliance later, directly with Kiwi. Some Kiwi recipes can be found in the Kiwi cookbook on openSUSE's wiki. Kiwi also supports generating an EC2 AMI, so this slight detour is a perfect way to generate an AMI for an appliance made by SUSE Studio if you can't wait for the support coming later this year.

A big selling point of SUSE Studio is the documentation on openSUSE's wiki. This varies from a FAQ, a tour, HOWTOs, and the API, to known issues, support channels, and downloads. The last features some appliances that users have built with SUSE Studio, such as a Mono 2.4 appliance, an Elisa Media Centre appliance, openSUSE images for netbooks, and a demo live cd of Marble Desktop Globe.

The HOWTOs seem to be of good quality and guide you through some elaborate tasks. The general HOWTOs are mostly related to firstboot scripts and kiosk-like appliances, while there are more specific KDE and Gnome HOWTOs. Other HOWTOs are related to the type of deployment, such as VMware, VirtualBox (the VMware images run fine in VirtualBox), disk images and live CDs.

An appliance in fifteen minutes

In the last few months, your author has tested some other Linux appliance building tools as well, and can say with confidence that SUSE Studio was the most impressive. While rBuilder Online is also a handy and efficient tool, which supports more Linux distributions than just the SUSE family and has a neat management console for the appliance, SUSE Studio is much more user-friendly. Another solution, VMware Studio 1.0, also doesn't match the user experience of SUSE Studio: the user has to run this appliance builder in VMware and download a whole DVD image for the distribution the appliance will be based on. Moreover, building the image can take hours and has to start over from scratch when the user makes the slightest error, such as a typo in a URI. Advantages of VMware Studio are the support for a lot of Linux distributions and the excellent documentation.

All in all, compared to its competitors, SUSE Studio is without doubt the most easy-to-use, the most well-engineered, and the most efficient appliance builder. Even someone without any previous experience can build a software appliance in fifteen minutes. If it would only offer more distributions than just the SUSE family for the operating system base, it would be even more interesting.