A preview of Fedora 22

Fedora 22 is currently scheduled to be released at the end of May. While certain changes—such as the switch from the Yum package manager to DNF—have received a fair share of attention already, there are quite a few other differences that users can expect to see in the final release.

Naturally, a great many packages will be updated. Run-of-the-mill applications can be bumped up to a newer release without fanfare, but updates to certain critical components (such as core libraries, servers, and development frameworks) require approval by the Fedora Engineering Steering Committee (FESCo) before they make it onto the official list of accepted changes.

The GNOME 3.16 release, for example, will be included in Fedora 22. That will provide users with access to a number of improvements, as well as giving them a taste of several new applications—like the e-book manager GNOME Books and the Unicode character browser GNOME Characters.

Arguably a bigger change, though, is the inclusion of KDE's Plasma 5 environment. Plasma 5 represents a major overhaul, moving to the Qt5 and KDE Frameworks 5 libraries (both of which were available in Fedora 21). Plasma 5 includes only the core KDE desktop components: the KWin window manager, workspaces, and settings. But it does offer a fully hardware-accelerated graphics stack that uses OpenGL ES. Updating individual KDE applications may take more time, since the move from Plasma 4 to Plasma 5 includes API breaks (Fedora's KDE special-interest group is patching some Plasma 4 applications and retiring others), but including Plasma 5 is an important milestone for KDE users.

At a much lower level, the default compiler in Fedora 22 will change to GCC 5. Only a handful of libraries and other packages in Fedora had to be recompiled with GCC 5, since most do not rely on version-specific compiler features. FESCo did consider rebuilding all of Fedora 22 with the updated compiler, but ultimately decided against it. There are several significant improvements to be found, however, most notably support for the OpenACC 2.0a specification and support for OpenMP 4.0 offloading. Both allow programs to more easily utilize hardware-acceleration devices like GPUs. GCC 5 also improves C++11 support and adds initial support for C++14.

Another under-the-hood improvement is an update to Glibc's Unicode data, from version 5.1 to version 7.0. Users who rely on European languages and locales may not notice the change, but it will bring long-awaited improvements to character support to a number of Indic, Asian, and Australasian languages. "Long-awaited" is quite literal in this case; Unicode 5.1 was released in April 2008.

Fedora 22 will also migrate a few important components from running X.Org to running on Wayland by default. First is the GNOME Display Manager (GDM) login screen, which will now run on Wayland by default, but can fall back to X in the event of a failure. Since the login screen is isolated from normal user sessions, this change will hopefully allow Fedora to field-test Wayland support without putting its users' sessions at any significant risk.

Second, Fedora 22 will move input devices from the old set of X.Org drivers to libinput on top of Wayland. For now, that change will only affect Fedora Workstation, and the input stack will provide an X.Org compatibility layer through the xorg-x11-drv-libinput driver, but it is an important change for the long term. Libinput provides a unified input model that functions the same regardless of the device; X.Org needed separate drivers for each device class (e.g., keyboard, trackpad, mouse, tablet).

Speaking of Fedora Workstation, one of the more significant outcomes of the Fedora.next effort was the introduction of multiple Fedora "products"—namely, Server, Workstation, and Cloud versions of Fedora, each of which is planned and managed by a distinct team. Fedora 21 was the first release to implement the products model, but the Fedora 22 release may be the first to really show how the new model will differentiate between the offerings.

For example, the Server product working group has added a new database server role for Fedora 22. This is a deployment mechanism that lets administrators easily set up a Fedora 22 box to act as a database server, which Fedora has never targeted before. Obviously, users have been able to configure Fedora machines to run databases, but it is hoped that by paying special attention to the packaging and configuration needs, the distribution can attract more server administrators. The deployment scheme uses the Cockpit administration tool for setup and database management.

Two other product-driven changes are still under development, but may yet be ready when Fedora 22 is released. The first is support for rpm-ostree, which implements Colin Walters's OSTree, an image-based means to deploy a Linux distribution. Rather than installing individual RPM packages, OSTree builds a new system image on a remote server for any requested set of changes, then deploys that image to the machine. The result is an update system that allows easy rollbacks, rapid replication across multiple machines, and atomic updates.

Rpm-ostree support is a dependency for the other change, support for Red Hat's Project Atomic deployment scheme. Project Atomic takes the image-based, atomic-update model of OSTree and tunes it to deploy Linux containers. The change slated for Fedora 22 is to allow a Fedora Cloud instance to be deployed as the Atomic "host" system on which containers will run. In addition to rpm-ostree support, this change involves ensuring that Fedora Cloud images will run under VirtualBox and libvirt/qemu as well as ensuring that they will run the latest Docker containers.

There are, of course, many other changes that users should look forward to in Fedora 22—it will be the first release to support the Elasticsearch search engine, for example, and users on UEFI machines will be able to update their Secure Boot blacklists. On the other hand, users who were following the password-strength debate of the last few months may note that the changes proposed to resolve that issue have been deferred to Fedora 23.

So far, the Fedora products model seems to working well for the distribution; it will be interesting to see where things head next after Fedora 22 is out the door. With the distribution looking for ways to attract new users, more tailoring of the individual products could certainly prove to be a plus.