NixOS 19.09 Notable Changes: Network Interfaces, Documentation, VLC, Solr, Hunspell, MySQL, Systemd-Timesyncd, Avahi, Cargo-Vendor, Consul, PulseAudio, Phabricator, Mercurial, and Trac

- Because of the systemd upgrade, some network interfaces might change their name. For details see [ upstream docs](https://www.freedesktop.org/software/systemd/man/systemd.net-naming-scheme.html#History) or [ our ticket](https://github.com/NixOS/nixpkgs/issues/71086). ## Other Notable Changes {#sec-release-19.09-notable-changes} - The `documentation` module gained an option named `documentation.nixos.includeAllModules` which makes the generated configuration.nix 5 manual page include all options from all NixOS modules included in a given `configuration.nix` configuration file. Currently, it is set to `false` by default as enabling it frequently prevents evaluation. But the plan is to eventually have it set to `true` by default. Please set it to `true` now in your `configuration.nix` and fix all the bugs it uncovers. - The `vlc` package gained support for Chromecast streaming, enabled by default. TCP port 8010 must be open for it to work, so something like `networking.firewall.allowedTCPPorts = [ 8010 ];` may be required in your configuration. Also consider enabling [ Accelerated Video Playback](https://wiki.nixos.org/wiki/Accelerated_Video_Playback) for better transcoding performance. - The following changes apply if the `stateVersion` is changed to 19.09 or higher. For `stateVersion = "19.03"` or lower the old behavior is preserved. - `solr.package` defaults to `pkgs.solr_8`. - The `hunspellDicts.fr-any` dictionary now ships with `fr_FR.{aff,dic}` which is linked to `fr-toutesvariantes.{aff,dic}`. - The `mysql` service now runs as `mysql` user. Previously, systemd did execute it as root, and mysql dropped privileges itself. This includes `ExecStartPre=` and `ExecStartPost=` phases. To accomplish that, runtime and data directory setup was delegated to RuntimeDirectory and tmpfiles. - With the upgrade to systemd version 242 the `systemd-timesyncd` service is no longer using `DynamicUser=yes`. In order for the upgrade to work we rely on an activation script to move the state from the old to the new directory. The older directory (prior `19.09`) was `/var/lib/private/systemd/timesync`. As long as the `system.config.stateVersion` is below `19.09` the state folder will migrated to its proper location (`/var/lib/systemd/timesync`), if required. - The package `avahi` is now built to look up service definitions from `/etc/avahi/services` instead of its output directory in the nix store. Accordingly the module `avahi` now supports custom service definitions via `services.avahi.extraServiceFiles`, which are then placed in the aforementioned directory. See avahi.service5 for more information on custom service definitions. - Since version 0.1.19, `cargo-vendor` honors package includes that are specified in the `Cargo.toml` file of Rust crates. `rustPlatform.buildRustPackage` uses `cargo-vendor` to collect and build dependent crates. Since this change in `cargo-vendor` changes the set of vendored files for most Rust packages, the hash that use used to verify the dependencies, `cargoSha256`, also changes. The `cargoSha256` hashes of all in-tree derivations that use `buildRustPackage` have been updated to reflect this change. However, third-party derivations that use `buildRustPackage` may have to be updated as well. - The `consul` package was upgraded past version `1.5`, so its deprecated legacy UI is no longer available. - The default resample-method for PulseAudio has been changed from the upstream default `speex-float-1` to `speex-float-5`. Be aware that low-powered ARM-based and MIPS-based boards will struggle with this so you'll need to set `hardware.pulseaudio.daemon.config.resample-method` back to `speex-float-1`. - The `phabricator` package and associated `httpd.extraSubservice`, as well as the `phd` service have been removed from nixpkgs due to lack of maintainer. - The `mercurial` `httpd.extraSubservice` has been removed from nixpkgs due to lack of maintainer. - The `trac` `httpd.extraSubservice` has been removed from nixpkgs because it was unmaintained.

This section details additional notable changes in NixOS 19.09, including potential network interface name changes due to the systemd upgrade. Other changes include a new option for including all module options in the NixOS manual, Chromecast streaming support for VLC, an updated default Solr package, dictionary updates for Hunspell, a change in user for the MySQL service, modifications to systemd-timesyncd state management, avahi service definition handling, cargo-vendor package inclusion changes, removal of the Consul legacy UI, PulseAudio resample-method update, and the removal of Phabricator, Mercurial, and Trac httpd subservices.