beviu
895946798f
This reverts commit 67b8817f26.
That commit introduces a new error when:
- switch-to-configuration-ng spawns the "per-user"
switch-to-configuration-ng (the one that does do_user_switch).
- That "per-user" switch-to-configuration-ng instance connects to the
D-Bus session bus, but the bus is not up yet.
- The D-Bus session bus is configured to use systemd socket activation
and is currently being started by the systemd user manager.
- The D-Bus session bus finishes starting. At this point, only
switch-to-configuration-ng is connected to it. Systemd is not
connected yet because it waits for a ready notification from the D-Bus
session bus.
- switch-to-configuration-ng starts listening for a NameOwnerChanged
signal with the org.freedesktop.systemd1 bus name.
- Systemd is notified that the D-Bus session bus is ready, so it
connects to it and acquires the name org.freedesktop.systemd1, which
triggers the NameOwnerChanged signal that we listen to.
- switch-to-configuration-ng marks systemd as reexecuted, but it's _not
started reexecuting yet_.
- Then switch-to-configuration-ng tells systemd to reexecute.
- The loop waiting for systemd to reexecute [1] is never entered.
- switch-to-configuration-ng asks systemd to restart a unit but that
fails because systemd is reexecuting and the method call is sent to
the old deamon.
The idea with #442756 was to:
1. Remove the timeout for the Reexecute method call because it would
fail in a non-obvious way when systemd took too much time to execute,
and that could happen when there are many .mount units.
2. While we're at it, use the NameOwnerChanged signal to determine when
systemd is done reexecuting before we proceed with the other systemd
calls, instead of waiting for the Reexecute method call to error.
But in fact, it seems like 2. is not a good idea. Waiting for the
NameOwnerChanged signal has the disadvantage of not letting us know if
it is due to our Reexecute method call or someone else's, or even just
systemd that's just connected to the D-Bus in between as is the case
here.
It might still be a good idea to increase the timeout for the Reexecute
method call to fix the original error, but at least let's revert the PR.
[1]: https://github.com/NixOS/nixpkgs/blob/ec481667d737b1b366ac55d72ec09d101d842533/pkgs/by-name/sw/switch-to-configuration-ng/src/src/main.rs#L989
Nixpkgs is a collection of over 120,000 software packages that can be installed with the Nix package manager. It also implements NixOS, a purely-functional Linux distribution.
Manuals
- NixOS Manual - how to install, configure, and maintain a purely-functional Linux distribution
- Nixpkgs Manual - contributing to Nixpkgs and using programming-language-specific Nix expressions
- Nix Package Manager Manual - how to write Nix expressions (programs), and how to use Nix command line tools
Community
- Discourse Forum
- Matrix Chat
- Official wiki
- Community-maintained list of ways to get in touch (Discord, Telegram, IRC, etc.)
Other Project Repositories
The sources of all official Nix-related projects are in the NixOS organization on GitHub. Here are some of the main ones:
- Nix - the purely functional package manager
- NixOps - the tool to remotely deploy NixOS machines
- nixos-hardware - NixOS profiles to optimize settings for different hardware
- Nix RFCs - the formal process for making substantial changes to the community
- NixOS homepage - the NixOS.org website
- hydra - our continuous integration system
- NixOS Branding - NixOS branding
Continuous Integration and Distribution
Nixpkgs and NixOS are built and tested by our continuous integration system, Hydra.
- Continuous package builds for unstable/master
- Continuous package builds for the NixOS 25.05 release
- Tests for unstable/master
- Tests for the NixOS 25.05 release
Artifacts successfully built with Hydra are published to cache at https://cache.nixos.org/. When successful build and test criteria are met, the Nixpkgs expressions are distributed via Nix channels.
Contributing
Nixpkgs is among the most active projects on GitHub. While thousands of open issues and pull requests might seem a lot at first, it helps consider it in the context of the scope of the project. Nixpkgs describes how to build tens of thousands of pieces of software and implements a Linux distribution. The GitHub Insights page gives a sense of the project activity.
Community contributions are always welcome through GitHub Issues and Pull Requests.
For more information about contributing to the project, please visit the contributing page.
Donations
The infrastructure for NixOS and related projects is maintained by a nonprofit organization, the NixOS Foundation. To ensure the continuity and expansion of the NixOS infrastructure, we are looking for donations to our organization.
You can donate to the NixOS foundation through SEPA bank transfers or by using Open Collective:
License
Nixpkgs is licensed under the MIT License.
Note
MIT license does not apply to the packages built by Nixpkgs, merely to the files in this repository (the Nix expressions, build scripts, NixOS modules, etc.). It also might not apply to patches included in Nixpkgs, which may be derivative works of the packages to which they apply. The aforementioned artifacts are all covered by the licenses of the respective packages.