- [btrbk](https://digint.ch/btrbk/index.html), a backup tool for btrfs subvolumes, taking advantage of btrfs specific capabilities to create atomic snapshots and transfer them incrementally to your backup locations. Available as [services.btrbk](options.html#opt-services.brtbk.instances).
- [geoipupdate](https://github.com/maxmind/geoipupdate), a GeoIP database updater from MaxMind. Available as [services.geoipupdate](options.html#opt-services.geoipupdate.enable).
- [sourcehut](https://sr.ht), a collection of tools useful for software development. Available as [services.sourcehut](options.html#opt-services.sourcehut.enable).
- [ucarp](https://download.pureftpd.org/pub/ucarp/README), an userspace implementation of the Common Address Redundancy Protocol (CARP). Available as [networking.ucarp](options.html#opt-networking.ucarp.enable).
- Users of flashrom should migrate to [programs.flashrom.enable](options.html#opt-programs.flashrom.enable) and add themselves to the `flashrom` group to be able to access programmers supported by flashrom.
- [buildkite-agent-metrics](https://github.com/buildkite/buildkite-agent-metrics), a command-line tool for collecting Buildkite agent metrics, now has a Prometheus exporter available as [services.prometheus.exporters.buildkite-agent](#opt-services.prometheus.exporters.buildkite-agent.enable).
-`consul` was upgraded to a new major release with breaking changes, see [upstream changelog](https://github.com/hashicorp/consul/releases/tag/v1.10.0).
-`yggdrasil` was upgraded to a new major release with breaking changes, see [upstream changelog](https://github.com/yggdrasil-network/yggdrasil-go/releases/tag/v0.4.0).
-`icingaweb2` was upgraded to a new release which requires a manual database upgrade, see [upstream changelog](https://github.com/Icinga/icingaweb2/releases/tag/v2.9.0).
- The setting [`services.openssh.logLevel`](options.html#opt-services.openssh.logLevel) `"VERBOSE"``"INFO"`. This brings NixOS in line with upstream and other Linux distributions, and reduces log spam on servers due to bruteforcing botnets.
However, if [`services.fail2ban.enable`](options.html#opt-services.fail2ban.enable) is `true`, the `fail2ban` will override the verbosity to `"VERBOSE"`, so that `fail2ban` can observe the failed login attempts from the SSH logs.
- Sway: The terminal emulator `rxvt-unicode` is no longer installed by default via `programs.sway.extraPackages`. The current default configuration uses `alacritty` (and soon `foot`) so this is only an issue when using a customized configuration and not installing `rxvt-unicode` explicitly.
- The `claws-mail` package now references the new GTK+ 3 release branch, major version 4. To use the GTK+ 2 releases, one can install the `claws-mail-gtk2` package.
- The wordpress module provides a new interface which allows to use different webservers with the new option [`services.wordpress.webserver`](options.html#opt-services.wordpress.webserver). Currently `httpd` and `nginx` are supported. The definitions of wordpress sites should now be set in [`services.wordpress.sites`](options.html#opt-services.wordpress.sites).
Sites definitions that use the old interface are automatically migrated in the new option. This backward compatibility will be removed in 22.05.