Unverified Commit 2e27234c authored by r-vdp's avatar r-vdp
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nixos/activation: deprecate reloading or restarting units from the activation script 

This deprecation is part of a bigger effort to deprecate activation scripts altogether, which will take place over several releases.
There are no in-tree usages of the now-deprecated reload/restart functionality.
parent 41e59b8e

doc/release-notes/rl-2605.section.md

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@@ -16,6 +16,8 @@ 
- `kanata` now requires `karabiner-dk` version 6.0+ or later.

  The package has been updated to use the new `karabiner-dk` package and the `darwinDriver` output stays at the version defined in the package.



- Reloading or restarting systemd units from the NixOS activation script is deprecated, and will be removed in NixOS 26.11. This deprecation is part of a bigger effort to deprecate activation scripts altogether, which will take place over several releases. There are no in-tree usages of the now-deprecated reload/restart functionality.



- `elegant-sddm` has been updated to be Qt6 compatible. Themes for SDDM are slightly different so read the [wiki](https://wiki.nixos.org/wiki/SDDM_Themes) for more.



- `iroh` has been removed and split up into `iroh-dns-server` and `iroh-relay`.

nixos/doc/manual/development/activation-script.section.md

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@@ -34,25 +34,6 @@ is also run when `nixos-rebuild dry-activate` is run. To differentiate between 
real and dry activation, the `$NIXOS_ACTION` environment variable can be

read which is set to `dry-activate` when a dry activation is done.



An activation script can write to special files instructing

`switch-to-configuration` to restart/reload units. The script will take these

requests into account and will incorporate the unit configuration as described

above. This means that the activation script will "fake" a modified unit file

and `switch-to-configuration` will act accordingly. By doing so, configuration

like [systemd.services.\<name\>.restartIfChanged](#opt-systemd.services) is

respected. Since the activation script is run **after** services are already

stopped, [systemd.services.\<name\>.stopIfChanged](#opt-systemd.services)

cannot be taken into account anymore and the unit is always restarted instead

of being stopped and started afterwards.



The files that can be written to are `/run/nixos/activation-restart-list` and

`/run/nixos/activation-reload-list` with their respective counterparts for

dry activation being `/run/nixos/dry-activation-restart-list` and

`/run/nixos/dry-activation-reload-list`. Those files can contain

newline-separated lists of unit names where duplicates are being ignored. These

files are not create automatically and activation scripts must take the

possibility into account that they have to create them first.



## NixOS snippets {#sec-activation-script-nixos-snippets}



There are some snippets NixOS enables by default because disabling them would
@@ -63,12 +44,8 @@ do: 
- `etc` sets up the contents of `/etc`, this includes systemd units and

  excludes `/etc/passwd`, `/etc/group`, and `/etc/shadow` (which are managed by

  the `users` snippet)

- `hostname` sets the system's hostname in the kernel (not in `/etc`)

- `modprobe` sets the path to the `modprobe` binary for module auto-loading

- `nix` prepares the nix store and adds a default initial channel

- `specialfs` is responsible for mounting filesystems like `/proc` and `sys`

- `users` creates and removes users and groups by managing `/etc/passwd`,

  `/etc/group` and `/etc/shadow`. This also creates home directories

- `usrbinenv` creates `/usr/bin/env`
 
- `var` creates some directories in `/var` that are not service-specific

- `wrappers` creates setuid wrappers like `sudo`

pkgs/by-name/sw/switch-to-configuration-ng/src/src/main.rs

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@@ -1443,6 +1443,13 @@ won't take effect until you reboot the system. 
            .map(|mut child| child.wait());



        // Handle the activation script requesting the restart or reload of a unit.



        if std::fs::exists(DRY_RESTART_BY_ACTIVATION_LIST_FILE)?

            || std::fs::exists(DRY_RELOAD_BY_ACTIVATION_LIST_FILE)?

        {

            eprintln!("WARN: restarting or reloading systemd units from the activation script is deprecated and will be removed in NixOS 26.11.");

        }



        for unit in std::fs::read_to_string(DRY_RESTART_BY_ACTIVATION_LIST_FILE)

            .unwrap_or_default()

            .lines()
@@ -1607,6 +1614,12 @@ won't take effect until you reboot the system. 
        }

    }



    if std::fs::exists(RESTART_BY_ACTIVATION_LIST_FILE)?

        || std::fs::exists(RELOAD_BY_ACTIVATION_LIST_FILE)?

    {

        eprintln!("WARN: restarting or reloading systemd units from the activation script is deprecated and will be removed in NixOS 26.11.");

    }



    // Handle the activation script requesting the restart or reload of a unit.

    for unit in std::fs::read_to_string(RESTART_BY_ACTIVATION_LIST_FILE)

        .unwrap_or_default()