To start with, this is not an official statement from Citrix. Rather, this is a collection of observations over the length of time at Citrix.
First thing to note is that in the history of Citrix, the company had respect for Unix/Linux, and the first product in 1991 was effectively an OS/2 version of supporting terminals. This model matched the classic Unix terminal framework. The vision was that Citrix would provide a solution with Microsoft-based applications to terminals. A lofty goal for 1989 when it was first formed.
However, there was a dark cloud present. Any consideration between 1989 and the last few years to use Linux in a server product was seen as conflict of interest related to the relationship with Microsoft.
In 1998, Citrix acquired Insignia. This was key to releasing clients that supported Mac, Linux, and Unix. The dividends for this continue to this day. This Linux Receiver is seen as one of the more important receivers and is still updated with relevant features.
Also in 1998, I worked as a system engineer for a reseller in Brisbane. The experience revealed plenty of direct customer exposure and the joys of supporting software that you cannot personally fix. Anyways, some of the customers were using Linux. In general, there were two camps. The government camp wanted to use Linux because it was cheap and they had the talent to support it (or so they thought). The second camp saw it as a powerful tool for engineers and designers. There was a bit of mistrust from the government group with any outside opinions. In my case, I was only supporting a trial of WinFrame for a much larger environment. Amazingly, they were using Samba with Linux as the backbone of their Windows desktops. Perhaps you can see the fun in that in the late 90’s.
The second group of people using Linux for workstations for engineers was much more interesting. Citrix had nothing for that at the time (as a server). As explained by the customer, they wanted a Linux server that could remote applications to users. It would not be until 2015, that this would be possible with a Citrix product.
For 1999, the MetaFrame for Unix product started development. The focus was to create a Unix-based server for Citrix. The release gained some momentum but avoided Linux. Even though not declared, the reason was probably to avoid upsetting Microsoft. In 2014, the core MFU/XAU codebase would form the early basis for the current Citrix Linux VDA.
In 2004, Citrix pursued SSL VPN companies to provide its first VPN solution. As part of this process, Net6 was acquired. The secret was that the Net6 appliance was actually running open source Linux. There were initially concerns about Microsoft’s reaction. However, the concerns were unfounded due the appliance not being the same model as Microsoft’s client/server environment.
An important 2005 acquisition was Netscaler. It too was based on a Linux appliance.
In 2007, Citrix acquired XenSource. The core of Xen virtualizations is Linux. This introduced the concept of Linux being an acceptable solution for virtualization.
In 2014, Ericsson approached Citrix to produce what was later called Linux VDA. The Citrix Labs team accepted the task and released the first version in June 2015. The model follows the design of Windows VDA, but customized to Linux hosts. Citrix receivers connect to Linux VDA the same way that they connect to Windows VDA. Given that the receiver is a recent one, it is designed to connect to either server without special treatment.
And to wrap things up, today Microsoft announced that they have developed a Linux network appliance for Azure. The age of upsetting Microsoft about using Linux is truly over.