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author | Janne Heß <dasJ@users.noreply.github.com> | 2024-01-18 16:13:32 +0100 |
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committer | GitHub <noreply@github.com> | 2024-01-18 16:13:32 +0100 |
commit | 15c31afd8ae99e9d3a2d6af0d804f3a53f6aa848 (patch) | |
tree | 3043b20b41c521e6abe599194cc7f00de485e54d /nixos/doc | |
parent | 15a34f609f4806aabff2d87428e1cc371b41d93c (diff) | |
parent | 8f3abd21aad719ea7018dc309450c0ed63dd3642 (diff) | |
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Merge pull request #271067 from nikstur/sysinit-reactivation
nixos/switch-to-configuration: add sysinit-reactivation.target
Diffstat (limited to 'nixos/doc')
3 files changed, 45 insertions, 1 deletions
diff --git a/nixos/doc/manual/development/unit-handling.section.md b/nixos/doc/manual/development/unit-handling.section.md index 32d44dbfff05..d5ba6a9529d0 100644 --- a/nixos/doc/manual/development/unit-handling.section.md +++ b/nixos/doc/manual/development/unit-handling.section.md @@ -63,3 +63,42 @@ checks: is **restart**ed with the others. If it is set, both the service and the socket are **stop**ped and the socket is **start**ed, leaving socket activation to start the service when it's needed. + +## Sysinit reactivation {#sec-sysinit-reactivation} + +[`sysinit.target`](https://www.freedesktop.org/software/systemd/man/latest/systemd.special.html#sysinit.target) +is a systemd target that encodes system initialization (i.e. early startup). A +few units that need to run very early in the bootup process are ordered to +finish before this target is reached. Probably the most notable one of these is +`systemd-tmpfiles-setup.service`. We will refer to these units as "sysinit +units". + +"Normal" systemd units, by default, are ordered AFTER `sysinit.target`. In +other words, these "normal" units expect all services ordered before +`sysinit.target` to have finished without explicity declaring this dependency +relationship for each dependency. See the [systemd +bootup](https://www.freedesktop.org/software/systemd/man/latest/bootup.html) +for more details on the bootup process. + +When restarting both a unit ordered before `sysinit.target` as well as one +after, this presents a problem because they would be started at the same time +as they do not explicitly declare their dependency relations. + +To solve this, NixOS has an artificial `sysinit-reactivation.target` which +allows you to ensure that services ordered before `sysinit.target` are +restarted correctly. This applies both to the ordering between these sysinit +services as well as ensuring that sysinit units are restarted before "normal" +units. + +To make an existing sysinit service restart correctly during system switch, you +have to declare: + +```nix +systemd.services.my-sysinit = { + requiredBy = [ "sysinit-reactivation.target" ]; + before = [ "sysinit-reactivation.target" ]; + restartTriggers = [ config.environment.etc."my-sysinit.d".source ]; +}; +``` + +You need to configure appropriate `restartTriggers` specific to your service. diff --git a/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md b/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md index ccadb819e061..5d17a9c98514 100644 --- a/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md +++ b/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md @@ -37,7 +37,7 @@ of actions is always the same: - Forget about the failed state of units (`systemctl reset-failed`) - Reload systemd (`systemctl daemon-reload`) - Reload systemd user instances (`systemctl --user daemon-reload`) -- Set up tmpfiles (`systemd-tmpfiles --create`) +- Reactivate sysinit (`systemctl restart sysinit-reactivation.target`) - Reload units (`systemctl reload`) - Restart units (`systemctl restart`) - Start units (`systemctl start`) diff --git a/nixos/doc/manual/release-notes/rl-2405.section.md b/nixos/doc/manual/release-notes/rl-2405.section.md index 84ece231efea..ae9352e9a921 100644 --- a/nixos/doc/manual/release-notes/rl-2405.section.md +++ b/nixos/doc/manual/release-notes/rl-2405.section.md @@ -114,6 +114,11 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m - The executable file names for `firefox-devedition`, `firefox-beta`, `firefox-esr` now matches their package names, which is consistent with the `firefox-*-bin` packages. The desktop entries are also updated so that you can have multiple editions of firefox in your app launcher. +- switch-to-configuration does not directly call systemd-tmpfiles anymore. + Instead, the new artificial sysinit-reactivation.target is introduced which + allows to restart multiple services that are ordered before sysinit.target + and respect the ordering between the services. + - The `systemd.oomd` module behavior is changed as: - Raise ManagedOOMMemoryPressureLimit from 50% to 80%. This should make systemd-oomd kill things less often, and fix issues like [this](https://pagure.io/fedora-workstation/issue/358). |