In addition to numerous new and upgraded packages, this release has the following highlights: The Haskell packages infrastructure has been re-designed from the ground up ("Haskell NG"). NixOS now distributes the latest version of every single package registered on Hackage -- well in excess of 8,000 Haskell packages. Detailed instructions on how to use that infrastructure can be found in the User's Guide to the Haskell Infrastructure. Users migrating from an earlier release may find helpful information below, in the list of backwards-incompatible changes. Furthermore, we distribute 51(!) additional Haskell package sets that provide every single LTS Haskell release since version 0.0 as well as the most recent Stackage Nightly snapshot. The announcement "Full Stackage Support in Nixpkgs" gives additional details. Nix has been updated to version 1.10, which among other improvements enables cryptographic signatures on binary caches for improved security. You can now keep your NixOS system up to date automatically by setting system.autoUpgrade.enable = true; This will cause the system to periodically check for updates in your current channel and run nixos-rebuild. This release is based on Glibc 2.21, GCC 4.9 and Linux 3.18. When upgrading from a previous release, please be aware of the following incompatible changes: sshd no longer supports DSA and ECDSA host keys by default. If you have existing systems with such host keys and want to continue to use them, please set system.stateVersion = "14.12"; The new option system.stateVersion ensures that certain configuration changes that could break existing systems (such as the sshd host key setting) will maintain compatibility with the specified NixOS release. NixOps sets the state version of existing deployments automatically. cron is no longer enabled by default, unless you have a non-empty services.cron.systemCronJobs. To force cron to be enabled, set services.cron.enable = true. Nix now requires binary caches to be cryptographically signed. If you have unsigned binary caches that you want to continue to use, you should set nix.requireSignedBinaryCaches = false. Steam now doesn't need root rights to work. Instead of using *-steam-chrootenv, you should now just run steam. steamChrootEnv package was renamed to steam, and old steam package -- to steamOriginal. CMPlayer has been renamed to bomi upstream. Package cmplayer was accordingly renamed to bomi Atom Shell has been renamed to Electron upstream. Package atom-shell was accordingly renamed to electron Elm is not released on Hackage anymore. You should now use elmPackages.elm which contains the latest Elm platform. The CUPS printing service has been updated to version 2.0.2. Furthermore its systemd service has been renamed to cups.service. Local printers are no longer shared or advertised by default. This behavior can be changed by enabling services.printing.defaultShared or services.printing.browsing respectively. The VirtualBox host and guest options have been named more consistently. They can now found in virtualisation.virtualbox.host.* instead of services.virtualboxHost.* and virtualisation.virtualbox.guest.* instead of services.virtualboxGuest.*. Also, there now is support for the vboxsf file system using the fileSystems configuration attribute. An example of how this can be used in a configuration: fileSystems."/shiny" = { device = "myshinysharedfolder"; fsType = "vboxsf"; }; "nix-env -qa" no longer discovers Haskell packages by name. The only packages visible in the global scope are ghc, cabal-install, and stack, but all other packages are hidden. The reason for this inconvenience is the sheer size of the Haskell package set. Name-based lookups are expensive, and most nix-env -qa operations would become much slower if we'd add the entire Hackage database into the top level attribute set. Instead, the list of Haskell packages can be displayed by running: nix-env -f "<nixpkgs>" -qaP -A haskellPackages Executable programs written in Haskell can be installed with: nix-env -f "<nixpkgs>" -iA haskellPackages.pandoc Installing Haskell libraries this way, however, is no longer supported. See the next item for more details. Previous versions of NixOS came with a feature called ghc-wrapper, a small script that allowed GHC to transparently pick up on libraries installed in the user's profile. This feature has been deprecated; ghc-wrapper was removed from the distribution. The proper way to register Haskell libraries with the compiler now is the haskellPackages.ghcWithPackages function. The User's Guide to the Haskell Infrastructure provides more information about this subject. All Haskell builds that have been generated with version 1.x of the cabal2nix utility are now invalid and need to be re-generated with a current version of cabal2nix to function. The most recent version of this tool can be installed by running nix-env -i cabal2nix. The haskellPackages set in Nixpkgs used to have a function attribute called extension that users could override in their ~/.nixpkgs/config.nix files to configure additional attributes, etc. That function still exists, but it's now called overrides. The OpenBLAS library has been updated to version 0.2.14. Support for the x86_64-darwin platform was added. Dynamic architecture detection was enabled; OpenBLAS now selects microarchitecture-optimized routines at runtime, so optimal performance is achieved without the need to rebuild OpenBLAS locally. OpenBLAS has replaced ATLAS in most packages which use an optimized BLAS or LAPACK implementation. The phpfpm is now using the default PHP version (pkgs.php) instead of PHP 5.4 (pkgs.php54). The locate service no longer indexes the Nix store by default, preventing packages with potentially numerous versions from cluttering the output. Indexing the store can be activated by setting services.locate.includeStore = true. The Nix expression search path (NIX_PATH) no longer contains /etc/nixos/nixpkgs by default. You can override NIX_PATH by setting nix.nixPath. Other notable improvements: The nixos and nixpkgs channels were unified, so one can use nix-env -iA nixos.bash instead of nix-env -iA nixos.pkgs.bash. See the commit for details. Users running an SSH server who worry about the quality of their /etc/ssh/moduli file with respect to the vulnerabilities discovered in the Diffie-Hellman key exchange can now replace OpenSSH's default version with one they generated themselves using the new services.openssh.moduliFile option. A newly packaged TeX Live 2015 is provided in pkgs.texlive, split into 6500 nix packages. For basic user documentation see the source. Beware of an issue when installing a too large package set. The plan is to deprecate and maybe delete the original TeX packages until the next release.