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
Add writeStringReferencesToFile, a builder which extracts a string's
references to derivations and paths and writes them to a text file,
removing the input string itself from the dependency graph. This is
useful when you want to make a derivation depend on the string's
references, but not its content (to avoid unnecessary rebuilds, for
example).
This fixes#126344, specifically with the goal of enabling overriding the
checkPhase argument. See `design notes` at the end for details.
This allows among other things, enabling bash extension for the `checkPhase`.
Previously using such bash extensions was prohibited by the `writeShellScript`
code because there was no way to enable the extension in the checker.
As an example:
```nix
(writeShellScript "foo" ''
shopt -s extglob
echo @(foo|bar)
'').overrideAttrs (old: {
checkPhase = ''
# use subshell to preserve outer environment
(
export BASHOPTS
shopt -s extglob
${old.checkPhase}
)
'';
})
```
This commit also adds tests for this feature to `pkgs/tests/default.nix`,
under `trivial-overriding`. The test code is located at
`pkgs/build-support/trivial-builders/test-overriding.nix`.
Design notes:
-------------
Per discussion with @sternenseemann, the original approach of just wrapping
`writeTextFile` in `makeOverridable` had the issue that combined with `callPackage`
in the following form, would shadow the `.override` attribute of the `writeTextFile`:
```nix
with import <nixpkgs>;
callPackage ({writeShellScript}: writeShellScript "foo" "echo foo")
```
A better approach can be seen in this commit, where `checkPhase` is moved
from an argument of `writeTextFile`, which is substituted into `buildCommand`,
into an `mkDerivation` argument, which is substituted from the environment
and `eval`-ed. (see the source)
This way we can simple use `.overideAttrs` as usual, and this also makes
`checkPhase` a bit more conformant to `mkDerivation` naming, with respect to
phases generally being overridable attrs.
Co-authored-by: sterni <sternenseemann@systemli.org>
Co-authored-by: Naïm Favier <n@monade.li>
> There is an issue in the test added by #123111.
> [it] introduces a dependency on the contents of nixpkgs,
> making every change evaluate with a different hash.
