Notable Changes in NixOS: Redis, Modules, FreeType, ZFS, Timezone, Overlays, Hosts, Installer, GitLab Runner, Jenkins, Postfix, GitLab, Systemd-boot, and dnscrypt-proxy

- Redis has been updated to version 4 which mandates a cluster mass-restart, due to changes in the network handling, in order to ensure compatibility with networks NATing traffic. ## Other Notable Changes {#sec-release-17.09-notable-changes} - Modules can now be disabled by using [ disabledModules](https://nixos.org/nixpkgs/manual/#sec-replace-modules), 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. - ZFS/SPL have been updated to 0.7.0, `zfsUnstable, splUnstable` have therefore been removed. - The `time.timeZone` option now allows the value `null` in addition to timezone strings. This value allows changing the timezone of a system imperatively using `timedatectl set-timezone`. The default timezone is still UTC. - Nixpkgs overlays may now be specified with a file as well as a directory. The value of `<nixpkgs-overlays>` may be a file, and `~/.config/nixpkgs/overlays.nix` can be used instead of the `~/.config/nixpkgs/overlays` directory. See the overlays chapter of the Nixpkgs manual for more details. - Definitions for `/etc/hosts` can now be specified declaratively with `networking.hosts`. - Two new options have been added to the installer loader, in addition to the default having changed. The kernel log verbosity has been lowered to the upstream default for the default options, in order to not spam the console when e.g. joining a network. This therefore leads to adding a new `debug` option to set the log level to the previous verbose mode, to make debugging easier, but still accessible easily. Additionally a `copytoram` option has been added, which makes it possible to remove the install medium after booting. This allows tethering from your phone after booting from it. - `services.gitlab-runner.configOptions` has been added to specify the configuration of gitlab-runners declaratively. - `services.jenkins.plugins` has been added to install plugins easily, this can be generated with jenkinsPlugins2nix. - `services.postfix.config` has been added to specify the main.cf with NixOS options. Additionally other options have been added to the postfix module and has been improved further. - The GitLab package and module have been updated to the latest 10.0 release. - The `systemd-boot` boot loader now lists the NixOS version, kernel version and build date of all bootable generations. - The dnscrypt-proxy service now defaults to using a random upstream resolver, selected from the list of public non-logging resolvers with DNSSEC support. Existing configurations can be migrated to this mode of operation by omitting the `services.dnscrypt-proxy.resolverName` option or setting it to `"random"`.

This section summarizes notable changes in NixOS. It includes updates to Redis requiring a cluster restart, the ability to disable modules, FreeType updates with a new engine, ZFS updates, timezone configuration, Nixpkgs overlays, declarative /etc/hosts definitions, installer loader options, GitLab Runner configuration, Jenkins plugin installation, Postfix configuration, GitLab updates, Systemd-boot improvements, and dnscrypt-proxy using random upstream resolvers.