As `nix-daemon.service` does not make use of `ExecStop`, we prefer
to keep the socket up and available. This is important for machines
that run Nix-based services, such as automated build, test, and deploy
services, that expect the daemon socket to be available at all times.
See committed inline comment for further explanation.
The `substituters` option in `nix.settings` uses the order
of the substituters listed to define priority. Prior to https://github.com/NixOS/nixpkgs/pull/139075,
the corresponding option `binaryCaches` is declared in the `nix` namespace,
which is guaranteed to be merged last. However, the order of merging isn't
guaranteed in submodules. This cause definitions to be appended to the default
value instead of prepended, breaking backwards compatibility as reported in https://github.com/NixOS/nixpkgs/issues/158356.
The way this is addressed in the module system is with order priorities via
`mkOrder` and sorting definitions before merging. This PR restores the previous
behavior by setting a higher priority to the substituters option defined internally,
thus all definitions with default priority will be merged before it. This was chosen because
the `mkRenamedOption` function does not preserve order priority so users using legacy options do not have
precise control on placement.
This change should suffice for simple configuration, but further revision to the module system
is needed for to make various `mk*` functions aware of order priorities.
In #139075, mandatoryFeatures was removed from the generated
supportedFeatures, which breaks backward compatibility and is
different from what the description of supportedFeatures says.
Fail scripts on pipeline errors and propagate subshell errors.
If an error occurs in a subshell, including while trying to read a
secret file, we want that error to propagate to the main shell
context. That means we have to set the `inherit_errexit` option, which
allows errors from subshells to propagate to the outer shell. Also,
the subshell cannot run as part of another command, such as `export`,
since that will simply ignore the subshell exit status and only
respect `export`s exit status; first assigning the value to a variable
and then exporting it solves issue.
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
