The eighth point release of UCS 4.4 provides preparations for the upgrade to the forthcoming UCS 5.0, performance improvements in large environments, and improvements in the App Center, AD, and S4 Connector. In this article, I would like to present the most important innovations.

Preparations for the Upgrade to UCS 5.0

As described in the blog post on UCS 5.0 Beta, the structure of the UCS package repository is changing fundamentally. In UCS, the “Univention Updater” is responsible for recognizing the repositories and carries out the UCS updates. With the release of UCS 4.4-8, it has been adapted to recognize the new repository structure of UCS 5 and offer the upgrade to UCS 5.0 as soon as it is published. The future repository structure speeds up App Center and package installations and saves space on our repository servers and the mirror servers in UCS environments. It also simplifies our release processes.

Furthermore, it has been ensured in the App Center that an upgrade to UCS 5.0 only takes place when the apps are also available in the App Center for UCS 5.0. That ensures that similar services continue to be available on a UCS system after the upgrade. We have decided to block individual UCS upgrades because mixed environments of UCS 4.4 and UCS 5.0 are supported. Besides, a few apps will only be available after the release of UCS 5.0.

With UCS 5.0, we will say goodbye to the Univention Virtual Machine Manager (UVMM) as announced (see blog post). With the availability of UCS 5.0, UCS environments are not usually fully updated in one go. As a result, there will be mixed environments of UCS 5.0 and UCS 4.4 for a certain period. In these mixed environments, it should still be possible to run UVMM on UCS 4.4, even if the Primary Directory Node has already been updated to UCS 5.0. UCS 4.4-8 ensures that the necessary scheme extensions are still in the directory service. Therefore, it is a prerequisite to update the entire UCS environment to UCS 4.4-8 before starting the update to UCS 5.

Performance Improvements in Large Environments

The performance of the UMC web server in large environments where there are many requests has improved. For this purpose, the UMC web server has changed from single to multi-processing. Thus, it can no longer run in one process only, but in several processes, to actively use several CPU cores, at the same time. The number of processes used is configurable and should not exceed the available CPU cores. In particular, large UCS environments with many login requests in a short period benefit from this change.

Advanced Parameterization of Docker-based Apps

App developers from the Univention App Center can now store the call command for their Docker-based apps as a UCR template. Therefore, they can enable further parameters for their app. Apps can be initialized using an additional path, depending on configuration parameters. The App Center thus meets the need for another option for initializing and configuring Docker-based apps. The UCS Dashboard Database makes use of this so that the storage duration of metrics can be configured differently from the standard.

Active Directory Connector and S4 Connector

There were numerous bug fixes in the AD Connector. One part dealt with checking the password quality and comparing corresponding specifications such as length, characters used, and referencing the password history. In particular, the reporting of error messages to the web interface improved. Now, the reason for a password rejection is easier to comprehend.

The S4 Connector now also synchronizes the gidNumber attribute of group objects. This information is necessary for systems that use an RFC2307 compliant idmap. The attribute is now synchronized from UCS to Samba 4 by default.

The complete list of fixes and bug fixes for UCS 4.4-8 is online. You can also find more information in the release notes. As always, if you have any requests or suggestions for improvement, we welcome your feedback. Here on the blog or at

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