{ config, pkgs, ... }:
with pkgs.lib;
let
cfg = config.nix;
inherit (config.environment) nix;
makeNixBuildUser = nr:
{ name = "nixbld${toString nr}";
description = "Nix build user ${toString nr}";
/* For consistency with the setgid(2), setuid(2), and setgroups(2)
calls in `libstore/build.cc', don't add any supplementary group
here except "nixbld". */
uid = builtins.add config.ids.uids.nixbld nr;
group = "nixbld";
extraGroups = [ "nixbld" ];
};
in
{
###### interface
options = {
environment.nix = mkOption {
default = pkgs.nix;
merge = mergeOneOption;
description = ''
This option specifies the Nix package instance to use throughout the system.
'';
};
nix = {
maxJobs = mkOption {
default = 1;
example = 2;
description = "
This option defines the maximum number of jobs that Nix will try
to build in parallel. The default is 1. You should generally
set it to the number of CPUs in your system (e.g., 2 on a Athlon
64 X2).
";
};
useChroot = mkOption {
default = false;
example = true;
description = "
If set, Nix will perform builds in a chroot-environment that it
will set up automatically for each build. This prevents
impurities in builds by disallowing access to dependencies
outside of the Nix store.
";
};
chrootDirs = mkOption {
default = [];
example = [ "/dev" "/proc" ];
description =
''
Directories from the host filesystem to be included
in the chroot.
'';
};
extraOptions = mkOption {
default = "";
example = "
gc-keep-outputs = true
gc-keep-derivations = true
";
description = "Additional text appended to nix.conf.";
};
distributedBuilds = mkOption {
default = false;
description = "
Whether to distribute builds to the machines listed in
.
If you know that the are not
always available either use nixos
nixos-rebuild --no-build-hook
or consider managing /etc/nix.machines manually
by setting . Then you can comment
unavailable buildmachines.
";
};
manualNixMachines = mkOption {
default = false;
description = "
Whether to manually manage the list of buildmachines used in distributed
builds in /etc/nix.machines.
";
};
daemonNiceLevel = mkOption {
default = 10;
description = "
Nix daemon process priority. This priority propagates to build processes.
0 is the default Unix process priority, 20 is the lowest.
";
};
daemonIONiceLevel = mkOption {
default = 7;
description = "
Nix daemon process I/O priority. This priority propagates to build processes.
0 is the default Unix process I/O priority, 7 is the lowest.
";
};
buildMachines = mkOption {
example = [
{ hostName = "voila.labs.cs.uu.nl";
sshUser = "nix";
sshKey = "/root/.ssh/id_buildfarm";
system = "powerpc-darwin";
maxJobs = 1;
}
{ hostName = "linux64.example.org";
sshUser = "buildfarm";
sshKey = "/root/.ssh/id_buildfarm";
system = "x86_64-linux";
maxJobs = 2;
}
];
description = "
This option lists the machines to be used if distributed
builds are enabled (see
). Nix will perform
derivations on those machines via SSh by copying the inputs to
the Nix store on the remote machine, starting the build, then
copying the output back to the local Nix store. Each element
of the list should be an attribute set containing the
machine's host name (hostname), the user
name to be used for the SSH connection
(sshUser), the Nix system type
(system, e.g.,
\"i686-linux\"), the maximum number of jobs
to be run in parallel on that machine
(maxJobs), and the path to the SSH private
key to be used to connect (sshKey). The
SSH private key should not have a passphrase, and the
corresponding public key should be added to
~sshUser/authorized_keys
on the remote machine.
";
};
proxy = mkOption {
default = "";
description = "
This option specifies the proxy to use for fetchurl. The real effect
is just exporting http_proxy, https_proxy and ftp_proxy with that
value.
";
example = "http://127.0.0.1:3128";
};
# Environment variables for running Nix. !!! Misnomer - it's
# actually a shell script.
envVars = mkOption {
internal = true;
default = {};
type = types.attrs;
description = "Environment variables used by Nix.";
};
nrBuildUsers = mkOption {
default = 10;
description = ''
Number of nixbld user accounts created to
perform secure concurrent builds. If you receive an error
message saying that “all build users are currently in use”,
you should increase this value.
'';
};
readOnlyStore = mkOption {
default = false;
description = ''
If set, NixOS will enforce the immutability of the Nix store
by making /nix/store a read-only bind
mount. Nix will automatically make the store writable when
needed.
'';
};
};
};
###### implementation
config = {
nix.chrootDirs = [ "/dev" "/dev/pts" "/proc" "/bin" ];
environment.etc =
[ { # Nix configuration.
source =
let
# Tricky: if we're using a chroot for builds, then we need
# /bin/sh in the chroot (our own compromise to purity).
# However, since /bin/sh is a symlink to some path in the
# Nix store, which furthermore has runtime dependencies on
# other paths in the store, we need the closure of /bin/sh
# in `build-chroot-dirs' - otherwise any builder that uses
# /bin/sh won't work.
binshDeps = pkgs.writeReferencesToFile config.system.build.binsh;
in
pkgs.runCommand "nix.conf" {extraOptions = cfg.extraOptions; } ''
extraPaths=$(for i in $(cat ${binshDeps}); do if test -d $i; then echo $i; fi; done)
cat > $out <