App Layering

Automating App and OS Layers

Back in May I attended my local CUGC where Ron Oglesby presented a master class on Citrix App Layering (ELM) and after the presentation, it was asked if there was any sort an SDK. Ron explained that there is no public API or SDK (yet), but some of the newer ELM components were built with this in mind. This statement resonated with me and when I got home that afternoon, I fired up Fiddler to see how the API worked. After a rather lengthy process of reverse engineering the API with Fiddler, Postman and documenting the processes I was able to write my SDK. When I completed the SDK I wasn’t really sure how it could be utilized in an environment or if there would be a need. Figured it would be more useful around documenting an ELM environment vs actually automating the creation or updating layers. I was under the impression that if an organization could automate layer creation, chances are they could automate the entire image making ELM redundant. However, after thinking about it for some time I now see ELM in combination with automation potentially being the stopgap between manual installs\updates and a fully automated build. By automating certain aspects of ELM it could allow organizations to tiptoe into automation and create a comfort level and free up time otherwise spent on updating common layers. This allows administrators to continue manually installing the difficult applications or even controlled by other teams but allowing automation to keep the common apps (e.g. Firefox, Chrome, Notepad Plus Plus…) and OS layers fully updated on regular intervals.

layer

The intent of this series of posts is how to approach automating some common apps and keeping the operating system layers fully updated.

  1. The first section will detail the steps needed for the script host and the base operating system layer allowing for automation.
  2. The second section will cover automatically building and updating app layers utilizing Choclatey packages.
  3. The third will cover continually keeping an operating system layer updated with Windows updates

Disclaimer

Just some notes before getting started.

  • The SDK in these posts isn’t supported by Citrix so please TEST fully and make sure you understand what's taking place.
  • These guides are by no means the only way to approach automating ELM but a proof a concept to show it can be done and others can hopefully use as a base.
  • The process isn’t necessarily the most secure but again this is to show the possibilities so please run with care.
  • I really hope Citrix sees the value in having a supported SDK and the possibilities it can create to further the adoption of ELM.
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