Next Gen Deployments: Modular Imaging
Disk images assist in desktop deployment by ensuring each computer is configured mostly the same, provides a time effective solution to deploying each computer and simplifies desktop management down the track amongst other things. The traditional process of creating the image is to setup a computer exactly as required and then to take a snapshot using any number of the disk imaging tools available. The method is very simple to follow and very effective. Unfortunately once you need to begin supporting multiple configurations the traditional method falls flat.
Enter modular imaging. With the capability of adding to or subtracting from the image on the fly while maintaining the exact foundation on all desktops, modular imaging has numerous advantages over the older snapshot based solution.
Packages
Just the same as applications are installed, modular imaging leverages the package distribution process to build the image. Each application is installed as the image is being built rather than by a human manually installing the application on the master computer. The image will be built exactly the same the first or tenth time it is created and not change unlike building images manually will.
Some applications are already installed by packages but most are simple drag and drop installs without an installation process. Such applications will need to be packaged so that they can be inserted into your image. Fortunately there are various applications available for free and commercially (see links) that wrap the application up in Apple’s package format.
Although the necessity of packaging everything may appear to complicate the image creation process the same packages can also be leveraged by post deployment strategies keeping deployed desktops up to date through Apple Remote Desktop, Casper and other similar solutions.
System Configuration
In Mac OS X every configuration is a file change. If the file that was changed can be located it could be packaged and slotted into the image. Alternatively actions can be performed by “payload free” packages that rather than install files will run a script. Further again to running scripts at installation time, first run on boot scripts can be used to complete final configuration after the desktop has been imaged.
Modular imaging may appear complicated on first investigation but once the methodologies of newer imaging processes are understood the possibilities and advantages quickly become apparent. Whether it is each version of an image created exactly the same each time it’s built or modified through to removing the need to recreate a brand new image next time an updated piece of hardware is released, the flexibility of modular imaging is the next natural step from traditional imaging.
Links
InstaDMG - solution to creating modular images.
Iceberg - free package authoring application.
Apple Remote Desktop - software deployment and remote control.
Casper - commercial desktop management and deployment solution.
fseventer - watches file system changes that aids you in determination of which file is needed for repackaging installers.
