When a NixOS system uses flakes, i.e., /etc/nixos/flake.nix exists, it
is impossible to use nixos-rebuild to build a pre-flake
configuration.nix. Of course, one can directly use nix command to
build the configuration, but not everybody remembers the correct nix
options to do that.
With the new option, it is possible to build a pre-flake configuration
with command like this:
nixos-rebuild build-vm -I nixos-config=./vm.nix --no-flake
The option might be useful for people following older pre-flake
tutorials on a flake-based system.
The `nix.*` options, apart from options for setting up the
daemon itself, currently provide a lot of setting mappings
for the Nix daemon configuration. The scope of the mapping yields
convience, but the line where an option is considered essential
is blurry. For instance, the `extra-sandbox-paths` mapping is
provided without its primary consumer, and the corresponding
`sandbox-paths` option is also not mapped.
The current system increases the maintenance burden as maintainers have to
closely follow upstream changes. In this case, there are two state versions
of Nix which have to be maintained collectively, with different options
avaliable.
This commit aims to following the standard outlined in RFC 42[1] to
implement a structural setting pattern. The Nix configuration is encoded
at its core as key-value pairs which maps nicely to attribute sets, making
it feasible to express in the Nix language itself. Some existing options are
kept such as `buildMachines` and `registry` which present a simplified interface
to managing the respective settings. The interface is exposed as `nix.settings`.
Legacy configurations are mapped to their corresponding options under `nix.settings`
for backwards compatibility.
Various options settings in other nixos modules and relevant tests have been
updated to use structural setting for consistency.
The generation and validation of the configration file has been modified to
use `writeTextFile` instead of `runCommand` for clarity. Note that validation
is now mandatory as strict checking of options has been pushed down to the
derivation level due to freeformType consuming unmatched options. Furthermore,
validation can not occur when cross-compiling due to current limitations.
A new option `publicHostKey` was added to the `buildMachines`
submodule corresponding to the base64 encoded public host key settings
exposed in the builder syntax. The build machine generation was subsequently
rewritten to use `concatStringsSep` for better performance by grouping
concatenations.
[1] - https://github.com/NixOS/rfcs/blob/master/rfcs/0042-config-option.md
There is no logical reason for --fast to imply --show-trace, and this
seems to be a historical accident. Using --show-trace by default is
bad UX since it can give very long error messages (e.g. 550 lines for
a non-existent attribute in environment.systemPackages).
Add --use-remote-sudo option. When set, remote commands will be prefixed
with 'sudo'. This allows using sudo remotely _without_ having to use
sudo locally (when using --build-host/--taget-host).
It seems as the sentence at the bottom of the option summary about
Nix-specific options isn't enough, it's probably more helpful to list
those options in the synopsis as well.
Since nix 2.0 the no-build-hook option was replaced by the builders options
that allows to override remote builders ad-hoc.
Since it is useful to disable remote builders updating nixos without network,
this commit reintroduces the option.
‘nixos-rebuild dry-activate’ builds the new configuration and then
prints what systemd services would be stopped, restarted etc. if the
configuration were actually activated. This could be extended later to
show other activation actions (like uids being deleted).
To prevent confusion, ‘nixos-rebuild dry-run’ has been renamed to
‘nixos-rebuild dry-build’.
