In addition to numerous new and upgraded packages, this release has the following highlights: The user handling now keeps track of deallocated UIDs/GIDs. When a user or group is revived, this allows it to be allocated the UID/GID it had before. A consequence is that UIDs and GIDs are no longer reused. The module option services.xserver.xrandrHeads now causes the first head specified in this list to be set as the primary head. Apart from that, it's now possible to also set additional options by using an attribute set, for example: { services.xserver.xrandrHeads = [ "HDMI-0" { output = "DVI-0"; primary = true; monitorConfig = '' Option "Rotate" "right" ''; } ]; } This will set the DVI-0 output to be the primary head, even though HDMI-0 is the first head in the list. The following new services were added since the last release: When upgrading from a previous release, please be aware of the following incompatible changes: aiccu package was removed. This is due to SixXS sunsetting its IPv6 tunnel. Top-level idea package collection was renamed. All JetBrains IDEs are now at jetbrains. flexget's state database cannot be upgraded to its new internal format, requiring removal of any existing db-config.sqlite which will be automatically recreated. The ipfs package now doesn't ignore the dataDir option anymore. If you've ever set this option to anything other than the default you'll have to either unset it (so the default gets used) or migrate the old data manually with dataDir=<valueOfDataDir> mv /var/lib/ipfs/.ipfs/* $dataDir rmdir /var/lib/ipfs/.ipfs The postgres default version was changed from 9.5 to 9.6. The postgres superuser name has changed from root to postgres to more closely follow what other Linux distributions are doing. The postgres default dataDir has changed from /var/db/postgres to /var/lib/postgresql/$psqlSchema where $psqlSchema is 9.6 for example. The caddy service was previously using an extra .caddy in the data directory specified with the dataDir option. The contents of the .caddy directory are now expected to be in the dataDir. Other notable improvements: Modules can now be disabled by using disabledModules, allowing another to take it's place. This can be used to import a set of modules from another channel while keeping the rest of the system on a stable release. Updated to FreeType 2.7.1, including a new TrueType engine. The new engine replaces the Infinality engine which was the default in NixOS. The default font rendering settings are now provided by fontconfig-penultimate, replacing fontconfig-ultimate; the new defaults are less invasive and provide rendering that is more consistent with other systems and hopefully with each font designer's intent. Some system-wide configuration has been removed from the Fontconfig NixOS module where user Fontconfig settings are available.