- Mattermost has been updated to extended support release 6.3, as the previously packaged extended support release 5.37 is [reaching its end of life](https://docs.mattermost.com/upgrade/extended-support-release.html).
Migrations may take a while, see the [changelog](https://docs.mattermost.com/install/self-managed-changelog.html#release-v6-3-extended-support-release)
and [important upgrade notes](https://docs.mattermost.com/upgrade/important-upgrade-notes.html).
- [aesmd](https://github.com/intel/linux-sgx#install-the-intelr-sgx-psw), the Intel SGX Architectural Enclave Service Manager. Available as [services.aesmd](#opt-services.aesmd.enable).
- [rootless Docker](https://docs.docker.com/engine/security/rootless/), a `systemd --user` Docker service which runs without root permissions. Available as [virtualisation.docker.rootless.enable](options.html#opt-virtualisation.docker.rootless.enable).
- [matrix-conduit](https://conduit.rs/), a simple, fast and reliable chat server powered by matrix. Available as [services.matrix-conduit](option.html#opt-services.matrix-conduit.enable).
- [filebeat](https://www.elastic.co/guide/en/beats/filebeat/current/filebeat-overview.html), a lightweight shipper for forwarding and centralizing log data. Available as [services.filebeat](#opt-services.filebeat.enable).
- [FRRouting](https://frrouting.org/), a popular suite of Internet routing protocol daemons (BGP, BFD, OSPF, IS-IS, VVRP and others). Available as [services.frr](#opt-services.ffr.babel.enable)
- [heisenbridge](https://github.com/hifi/heisenbridge), a bouncer-style Matrix IRC bridge. Available as [services.heisenbridge](options.html#opt-services.heisenbridge.enable).
- [PowerDNS-Admin](https://github.com/ngoduykhanh/PowerDNS-Admin), a web interface for the PowerDNS server. Available at [services.powerdns-admin](options.html#opt-services.powerdns-admin.enable).
- [mtr-exporter](https://github.com/mgumz/mtr-exporter), a Prometheus exporter for mtr metrics. Available as [services.mtr-exporter](options.html#opt-services.mtr-exporter.enable).
- [tetrd](https://tetrd.app), share your internet connection from your device to your PC and vice versa through a USB cable. Available at [services.tetrd](#opt-services.tetrd.enable).
- [ArchiSteamFarm](https://github.com/JustArchiNET/ArchiSteamFarm), a C# application with primary purpose of idling Steam cards from multiple accounts simultaneously. Available as [services.archisteamfarm](options.html#opt-services.archisteamfarm.enable).
- [teleport](https://goteleport.com), allows engineers and security professionals to unify access for SSH servers, Kubernetes clusters, web applications, and databases across all environments. Available at [services.teleport](#opt-services.teleport.enable).
- [prosody-filer](https://github.com/ThomasLeister/prosody-filer), a server for handling XMPP HTTP Upload requests. Available at [services.prosody-filer](#opt-services.prosody-filer.enable).
- [timetagger](https://timetagger.app), an open source time-tracker with an intuitive user experience and powerful reporting. [services.timetagger](options.html#opt-services.timetagger.enable).
- [rstudio-server](https://www.rstudio.com/products/rstudio/#rstudio-server), a browser-based version of the RStudio IDE for the R programming language. Available as [services.rstudio-server](options.html#opt-services.rstudio-server.enable).
- The `wafHook` hook now honors `NIX_BUILD_CORES` when `enableParallelBuilding` is not set explicitly. Packages can restore the old behaviour by setting `enableParallelBuilding=false`.
- The `writers.writePython2` and corresponding `writers.writePython2Bin` convenience functions to create executable Python 2 scripts in the store were removed in preparation of removal of the Python 2 interpreter.
Scripts have to be converted to Python 3 for use with `writers.writePython3` or `writers.writePyPy2` needs to be used.
- The `autorestic` package has been upgraded from 1.3.0 to 1.5.0 which introduces breaking changes in config file, check [their migration guide](https://autorestic.vercel.app/migration/1.4_1.5) for more details.
-`documentation.man` has been refactored to support choosing a man implementation other than GNU's `man-db`. For this, `documentation.man.manualPages` has been renamed to `documentation.man.man-db.manualPages`. If you want to use the new alternative man implementation `mandoc`, add `documentation.man = { enable = true; man-db.enable = false; mandoc.enable = true; }` to your configuration.
- Normal users (with `isNormalUser = true`) which have non-empty `subUidRanges` or `subGidRanges` set no longer have additional implicit ranges allocated. To enable automatic allocation back set `autoSubUidGidRange = true`.
- MultiMC has been replaced with the fork PolyMC due to upstream developers being hostile to 3rd party package maintainers. PolyMC removes all MultiMC branding and is aimed at providing proper 3rd party packages like the one contained in Nixpkgs. This change affects the data folder where game instances and other save and configuration files are stored. Users with existing installations should rename `~/.local/share/multimc` to `~/.local/share/polymc`. The main config file's path has also moved from `~/.local/share/multimc/multimc.cfg` to `~/.local/share/polymc/polymc.cfg`.
- The interface that allows activation scripts to restart units has been reworked. Restarting and reloading is now done by a single file `/run/nixos/activation-restart-list` that honors `restartIfChanged` and `reloadIfChanged` of the units.
- The `writers.writePyPy2`/`writers.writePyPy3` and corresponding `writers.writePyPy2Bin`/`writers.writePyPy3Bin` convenience functions to create executable Python 2/3 scripts using the PyPy interpreter were added.
- The `services.stubby` module was converted to a [settings-style](https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md) configuration.
- The option `services.thelounge.plugins` has been added to allow installing plugins for The Lounge. Plugins can be found in `pkgs.theLoungePlugins.plugins` and `pkgs.theLoungePlugins.themes`.
- The `zrepl` package has been updated from 0.4.0 to 0.5:
* The RPC protocol version was bumped; all zrepl daemons in a setup must be updated and restarted before replication can resume.
* A bug involving encrypt-on-receive has been fixed. Read the [zrepl documentation](https://zrepl.github.io/configuration/sendrecvoptions.html#job-recv-options-placeholder) and check the output of `zfs get -r encryption,zrepl:placeholder PATH_TO_ROOTFS` on the receiver.