ae4e94d9ac
Suggested by Mathijs Kwik. ‘boot.systemd’ is a misnomer because systemd affects more than just booting. And it saves some typing.
360 lines
12 KiB
Nix
360 lines
12 KiB
Nix
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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cfg = config.nix;
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inherit (config.environment) nix;
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makeNixBuildUser = nr:
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{ name = "nixbld${toString nr}";
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description = "Nix build user ${toString nr}";
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/* For consistency with the setgid(2), setuid(2), and setgroups(2)
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calls in `libstore/build.cc', don't add any supplementary group
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here except "nixbld". */
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uid = builtins.add config.ids.uids.nixbld nr;
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group = "nixbld";
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extraGroups = [ "nixbld" ];
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};
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in
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{
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###### interface
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options = {
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environment.nix = mkOption {
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default = pkgs.nix;
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merge = mergeOneOption;
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description = ''
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This option specifies the Nix package instance to use throughout the system.
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'';
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};
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nix = {
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maxJobs = mkOption {
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default = 1;
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example = 2;
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description = "
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This option defines the maximum number of jobs that Nix will try
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to build in parallel. The default is 1. You should generally
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set it to the number of CPUs in your system (e.g., 2 on a Athlon
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64 X2).
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";
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};
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useChroot = mkOption {
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default = false;
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example = true;
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description = "
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If set, Nix will perform builds in a chroot-environment that it
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will set up automatically for each build. This prevents
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impurities in builds by disallowing access to dependencies
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outside of the Nix store.
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";
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};
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chrootDirs = mkOption {
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default = [];
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example = [ "/dev" "/proc" ];
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description =
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''
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Directories from the host filesystem to be included
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in the chroot.
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'';
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};
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extraOptions = mkOption {
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default = "";
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example = "
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gc-keep-outputs = true
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gc-keep-derivations = true
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";
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description = "Additional text appended to <filename>nix.conf</filename>.";
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};
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distributedBuilds = mkOption {
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default = false;
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description = "
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Whether to distribute builds to the machines listed in
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<option>nix.buildMachines</option>.
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If you know that the <option>buildMachines</option> are not
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always available either use nixos
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<command>nixos-rebuild --no-build-hook</command>
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or consider managing <filename>/etc/nix.machines</filename> manually
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by setting <option>manualNixMachines</option>. Then you can comment
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unavailable buildmachines.
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";
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};
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manualNixMachines = mkOption {
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default = false;
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description = "
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Whether to manually manage the list of buildmachines used in distributed
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builds in /etc/nix.machines.
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";
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};
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daemonNiceLevel = mkOption {
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default = 10;
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description = "
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Nix daemon process priority. This priority propagates to build processes.
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0 is the default Unix process priority, 20 is the lowest.
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";
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};
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daemonIONiceLevel = mkOption {
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default = 7;
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description = "
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Nix daemon process I/O priority. This priority propagates to build processes.
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0 is the default Unix process I/O priority, 7 is the lowest.
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";
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};
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buildMachines = mkOption {
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example = [
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{ hostName = "voila.labs.cs.uu.nl";
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sshUser = "nix";
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sshKey = "/root/.ssh/id_buildfarm";
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system = "powerpc-darwin";
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maxJobs = 1;
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}
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{ hostName = "linux64.example.org";
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sshUser = "buildfarm";
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sshKey = "/root/.ssh/id_buildfarm";
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system = "x86_64-linux";
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maxJobs = 2;
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}
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];
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description = "
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This option lists the machines to be used if distributed
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builds are enabled (see
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<option>nix.distributedBuilds</option>). Nix will perform
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derivations on those machines via SSh by copying the inputs to
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the Nix store on the remote machine, starting the build, then
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copying the output back to the local Nix store. Each element
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of the list should be an attribute set containing the
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machine's host name (<varname>hostname</varname>), the user
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name to be used for the SSH connection
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(<varname>sshUser</varname>), the Nix system type
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(<varname>system</varname>, e.g.,
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<literal>\"i686-linux\"</literal>), the maximum number of jobs
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to be run in parallel on that machine
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(<varname>maxJobs</varname>), and the path to the SSH private
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key to be used to connect (<varname>sshKey</varname>). The
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SSH private key should not have a passphrase, and the
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corresponding public key should be added to
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<filename>~<replaceable>sshUser</replaceable>/authorized_keys</filename>
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on the remote machine.
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";
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};
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proxy = mkOption {
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default = "";
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description = "
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This option specifies the proxy to use for fetchurl. The real effect
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is just exporting http_proxy, https_proxy and ftp_proxy with that
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value.
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";
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example = "http://127.0.0.1:3128";
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};
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# Environment variables for running Nix. !!! Misnomer - it's
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# actually a shell script.
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envVars = mkOption {
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internal = true;
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default = {};
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type = types.attrs;
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description = "Environment variables used by Nix.";
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};
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nrBuildUsers = mkOption {
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default = 10;
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description = ''
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Number of <literal>nixbld</literal> user accounts created to
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perform secure concurrent builds. If you receive an error
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message saying that “all build users are currently in use”,
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you should increase this value.
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'';
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};
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readOnlyStore = mkOption {
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default = false;
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description = ''
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If set, NixOS will enforce the immutability of the Nix store
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by making <filename>/nix/store</filename> a read-only bind
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mount. Nix will automatically make the store writable when
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needed.
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'';
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};
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binaryCaches = mkOption {
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default = [ http://nixos.org/binary-cache ];
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type = types.list types.string;
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description = ''
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List of binary cache URLs used to obtain pre-built binaries
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of Nix packages.
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'';
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};
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trustedBinaryCaches = mkOption {
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default = [ ];
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example = [ http://hydra.nixos.org/ ];
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type = types.list types.string;
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description = ''
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List of binary cache URLs that non-root users can use (in
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addition to those specified using
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<option>nix.binaryCaches</option> by passing
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<literal>--option binary-caches</literal> to Nix commands.
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'';
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};
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};
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};
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###### implementation
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config = {
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nix.chrootDirs = [ "/dev" "/dev/pts" "/proc" "/bin" ];
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environment.etc =
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[ { # Nix configuration.
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source =
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let
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# Tricky: if we're using a chroot for builds, then we need
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# /bin/sh in the chroot (our own compromise to purity).
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# However, since /bin/sh is a symlink to some path in the
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# Nix store, which furthermore has runtime dependencies on
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# other paths in the store, we need the closure of /bin/sh
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# in `build-chroot-dirs' - otherwise any builder that uses
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# /bin/sh won't work.
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binshDeps = pkgs.writeReferencesToFile config.system.build.binsh;
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in
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pkgs.runCommand "nix.conf" {extraOptions = cfg.extraOptions; } ''
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extraPaths=$(for i in $(cat ${binshDeps}); do if test -d $i; then echo $i; fi; done)
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cat > $out <<END
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# WARNING: this file is generated.
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build-users-group = nixbld
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build-max-jobs = ${toString (cfg.maxJobs)}
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build-use-chroot = ${if cfg.useChroot then "true" else "false"}
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build-chroot-dirs = ${toString cfg.chrootDirs} $(echo $extraPaths)
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binary-caches = ${toString cfg.binaryCaches}
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trusted-binary-caches = ${toString cfg.trustedBinaryCaches}
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$extraOptions
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END
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'';
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target = "nix/nix.conf";
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}
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]
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++ optional (cfg.distributedBuilds && !cfg.manualNixMachines)
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{ # List of machines for distributed Nix builds in the format expected
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# by build-remote.pl.
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source = pkgs.writeText "nix.machines"
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(concatStrings (map (machine:
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"${machine.sshUser}@${machine.hostName} "
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+ (if machine ? system then machine.system else concatStringsSep "," machine.systems)
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+ " ${machine.sshKey} ${toString machine.maxJobs} "
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+ (if machine ? speedFactor then toString machine.speedFactor else "1" )
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+ "\n"
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) cfg.buildMachines));
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target = "nix.machines";
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};
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systemd.sockets."nix-daemon" =
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{ description = "Nix Daemon Socket";
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wantedBy = [ "sockets.target" ];
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before = [ "multi-user.target" ];
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socketConfig.ListenStream = "/nix/var/nix/daemon-socket/socket";
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};
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systemd.services."nix-daemon" =
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{ description = "Nix Daemon";
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path = [ nix pkgs.openssl pkgs.utillinux ]
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++ optionals cfg.distributedBuilds [ pkgs.openssh pkgs.gzip ];
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environment = cfg.envVars;
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serviceConfig =
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{ ExecStart = "@${nix}/bin/nix-daemon nix-daemon";
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KillMode = "process";
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Nice = cfg.daemonNiceLevel;
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IOSchedulingPriority = cfg.daemonIONiceLevel;
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LimitNOFILE = 4096;
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};
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};
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nix.envVars =
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{ NIX_CONF_DIR = "/etc/nix";
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# Enable the copy-from-other-stores substituter, which allows builds
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# to be sped up by copying build results from remote Nix stores. To
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# do this, mount the remote file system on a subdirectory of
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# /var/run/nix/remote-stores.
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NIX_OTHER_STORES = "/var/run/nix/remote-stores/*/nix";
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}
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// optionalAttrs cfg.distributedBuilds {
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NIX_BUILD_HOOK = "${config.environment.nix}/libexec/nix/build-remote.pl";
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NIX_REMOTE_SYSTEMS = "/etc/nix.machines";
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NIX_CURRENT_LOAD = "/var/run/nix/current-load";
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}
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# !!! These should not be defined here, but in some general proxy configuration module!
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// optionalAttrs (cfg.proxy != "") {
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http_proxy = cfg.proxy;
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https_proxy = cfg.proxy;
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ftp_proxy = cfg.proxy;
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};
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environment.shellInit =
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''
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# Set up the environment variables for running Nix.
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${concatMapStrings (n: "export ${n}=\"${getAttr n cfg.envVars}\"\n") (attrNames cfg.envVars)}
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# Set up secure multi-user builds: non-root users build through the
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# Nix daemon.
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if test "$USER" != root; then
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export NIX_REMOTE=daemon
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else
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export NIX_REMOTE=
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fi
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'';
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users.extraUsers = map makeNixBuildUser (range 1 cfg.nrBuildUsers);
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system.activationScripts.nix = stringAfter [ "etc" "users" ]
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''
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# Nix initialisation.
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mkdir -m 0755 -p \
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/nix/var/nix/gcroots \
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/nix/var/nix/temproots \
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/nix/var/nix/manifests \
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/nix/var/nix/userpool \
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/nix/var/nix/profiles \
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/nix/var/nix/db \
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/nix/var/log/nix/drvs \
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/nix/var/nix/channel-cache \
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/nix/var/nix/chroots
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mkdir -m 1777 -p \
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/nix/var/nix/gcroots/per-user \
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/nix/var/nix/profiles/per-user \
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/nix/var/nix/gcroots/tmp
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ln -sf /nix/var/nix/profiles /nix/var/nix/gcroots/
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ln -sf /nix/var/nix/manifests /nix/var/nix/gcroots/
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'';
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};
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}
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