{ config, pkgs, ... }: with pkgs.lib; let cfg = config.nix; nix = cfg.package; makeNixBuildUser = nr: { name = "nixbld${toString nr}"; description = "Nix build user ${toString nr}"; /* For consistency with the setgid(2), setuid(2), and setgroups(2) calls in `libstore/build.cc', don't add any supplementary group here except "nixbld". */ uid = builtins.add config.ids.uids.nixbld nr; group = "nixbld"; extraGroups = [ "nixbld" ]; }; nixConf = let # Tricky: if we're using a chroot for builds, then we need # /bin/sh in the chroot (our own compromise to purity). # However, since /bin/sh is a symlink to some path in the # Nix store, which furthermore has runtime dependencies on # other paths in the store, we need the closure of /bin/sh # in `build-chroot-dirs' - otherwise any builder that uses # /bin/sh won't work. binshDeps = pkgs.writeReferencesToFile config.system.build.binsh; in pkgs.runCommand "nix.conf" {extraOptions = cfg.extraOptions; } '' extraPaths=$(for i in $(cat ${binshDeps}); do if test -d $i; then echo $i; fi; done) cat > $out <nix.buildMachines. ''; }; daemonNiceLevel = mkOption { type = types.int; default = 0; description = '' Nix daemon process priority. This priority propagates to build processes. 0 is the default Unix process priority, 20 is the lowest. ''; }; daemonIONiceLevel = mkOption { type = types.int; default = 0; 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 { type = types.listOf types.attrs; default = []; 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; supportedFeatures = "kvm"; mandatoryFeatures = "perf"; } ]; 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), the path to the SSH private key to be used to connect (sshKey), a list of supported features of the machine (supportedFeatures) and a list of mandatory features of the machine (mandatoryFeatures). 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 { type = types.str; 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. envVars = mkOption { type = types.attrs; internal = true; default = {}; description = "Environment variables used by Nix."; }; nrBuildUsers = mkOption { type = types.int; 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 { type = types.bool; default = true; 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. ''; }; binaryCaches = mkOption { type = types.listOf types.str; default = [ http://cache.nixos.org/ ]; description = '' List of binary cache URLs used to obtain pre-built binaries of Nix packages. ''; }; trustedBinaryCaches = mkOption { type = types.listOf types.str; default = [ ]; example = [ http://hydra.nixos.org/ ]; description = '' List of binary cache URLs that non-root users can use (in addition to those specified using by passing --option binary-caches to Nix commands. ''; }; }; }; ###### implementation config = { nix.chrootDirs = [ "/dev" "/dev/pts" "/proc" "/bin" ]; environment.etc."nix/nix.conf".source = nixConf; # List of machines for distributed Nix builds in the format # expected by build-remote.pl. environment.etc."nix/machines" = { enable = cfg.buildMachines != []; text = concatMapStrings (machine: "${machine.sshUser}@${machine.hostName} " + (if machine ? system then machine.system else concatStringsSep "," machine.systems) + " ${machine.sshKey} ${toString machine.maxJobs} " + (if machine ? speedFactor then toString machine.speedFactor else "1" ) + " " + (if machine ? supportedFeatures then concatStringsSep "," machine.supportedFeatures else "" ) + " " + (if machine ? mandatoryFeatures then concatStringsSep "," machine.mandatoryFeatures else "" ) + "\n" ) cfg.buildMachines; }; systemd.sockets."nix-daemon" = { description = "Nix Daemon Socket"; wantedBy = [ "sockets.target" ]; before = [ "multi-user.target" ]; unitConfig.ConditionPathIsReadWrite = "/nix/var/nix/daemon-socket/"; socketConfig.ListenStream = "/nix/var/nix/daemon-socket/socket"; }; systemd.services."nix-daemon" = { description = "Nix Daemon"; path = [ nix pkgs.openssl pkgs.utillinux ] ++ optionals cfg.distributedBuilds [ pkgs.openssh pkgs.gzip ]; environment = cfg.envVars // { CURL_CA_BUNDLE = "/etc/ssl/certs/ca-bundle.crt"; }; unitConfig.ConditionPathIsReadWrite = "/nix/var/nix/daemon-socket/"; serviceConfig = { ExecStart = "@${nix}/bin/nix-daemon nix-daemon --daemon"; KillMode = "process"; Nice = cfg.daemonNiceLevel; IOSchedulingPriority = cfg.daemonIONiceLevel; LimitNOFILE = 4096; }; restartTriggers = [ nixConf ]; }; nix.envVars = { NIX_CONF_DIR = "/etc/nix"; # Enable the copy-from-other-stores substituter, which allows # builds to be sped up by copying build results from remote # Nix stores. To do this, mount the remote file system on a # subdirectory of /run/nix/remote-stores. NIX_OTHER_STORES = "/run/nix/remote-stores/*/nix"; } // optionalAttrs cfg.distributedBuilds { NIX_BUILD_HOOK = "${nix}/libexec/nix/build-remote.pl"; NIX_REMOTE_SYSTEMS = "/etc/nix/machines"; NIX_CURRENT_LOAD = "/run/nix/current-load"; } # !!! These should not be defined here, but in some general proxy configuration module! // optionalAttrs (cfg.proxy != "") { http_proxy = cfg.proxy; https_proxy = cfg.proxy; ftp_proxy = cfg.proxy; }; # Set up the environment variables for running Nix. environment.variables = cfg.envVars; environment.extraInit = '' # Set up secure multi-user builds: non-root users build through the # Nix daemon. if [ "$USER" != root -o ! -w /nix/var/nix/db ]; then export NIX_REMOTE=daemon fi ''; users.extraUsers = map makeNixBuildUser (range 1 cfg.nrBuildUsers); system.activationScripts.nix = stringAfter [ "etc" "users" ] '' # Nix initialisation. mkdir -m 0755 -p \ /nix/var/nix/gcroots \ /nix/var/nix/temproots \ /nix/var/nix/manifests \ /nix/var/nix/userpool \ /nix/var/nix/profiles \ /nix/var/nix/db \ /nix/var/log/nix/drvs \ /nix/var/nix/channel-cache \ /nix/var/nix/chroots mkdir -m 1777 -p \ /nix/var/nix/gcroots/per-user \ /nix/var/nix/profiles/per-user \ /nix/var/nix/gcroots/tmp ln -sf /nix/var/nix/profiles /nix/var/nix/gcroots/ ln -sf /nix/var/nix/manifests /nix/var/nix/gcroots/ ''; }; }