nixos-configuration/nixosModules/distributed-builds.nix

106 lines
3.2 KiB
Nix

{
config,
lib,
devices,
...
}:
let
sshKeyPath = "/etc/nix/distributed-build-key";
buildUser = "remotebuild";
# Collect all per-device public keys that have been registered.
authorizedPublicKeys = lib.pipe devices [
(lib.filterAttrs (_: v: (v.distributedBuilds or { }) ? clientPublicKey))
(lib.mapAttrsToList (_: v: v.distributedBuilds.clientPublicKey))
];
buildServerDevices = lib.filterAttrs (
_: v: (v.distributedBuilds or { }).isBuilder or false
) devices;
knownHosts = lib.pipe buildServerDevices [
(lib.filterAttrs (_: v: v.distributedBuilds ? hostPublicKey))
(lib.mapAttrs (
_: v: {
publicKey = v.distributedBuilds.hostPublicKey;
}
))
];
buildMachineList = lib.mapAttrsToList (
hostName: v:
{
inherit hostName;
systems = [ v.system ];
sshUser = buildUser;
sshKey = sshKeyPath;
protocol = "ssh-ng";
}
// lib.optionalAttrs (v.distributedBuilds ? speedFactor) {
speedFactor = v.distributedBuilds.speedFactor;
}
// {
supportedFeatures = [
"nixos-test"
"big-parallel"
"kvm"
"benchmark"
];
}
) buildServerDevices;
remoteMachines = builtins.filter (m: m.hostName != config.networking.hostName) buildMachineList;
in
{
options.my.distributedBuilds.enable = lib.mkEnableOption "distributed Nix builds";
config = lib.mkIf config.my.distributedBuilds.enable {
programs.ssh.knownHosts = knownHosts;
# Dedicated user for receiving distributed build connections
users.users.${buildUser} = {
isSystemUser = true;
group = buildUser;
useDefaultShell = true;
openssh.authorizedKeys.keys = map (
k: ''command="nix daemon --stdio",restrict ${k}''
) authorizedPublicKeys;
};
users.groups.${buildUser} = { };
nix = {
distributedBuilds = remoteMachines != [ ];
buildMachines = remoteMachines;
settings = {
trusted-users = [ buildUser ];
builders-use-substitutes = true;
# Use build machines as binary caches so already-built paths are downloaded
# rather than rebuilt. Only machines with a storeSigningPublicKey are used.
substituters = lib.pipe buildServerDevices [
(lib.filterAttrs (_: v: v.distributedBuilds ? storeSigningPublicKey))
(lib.mapAttrsToList (hostName: _: "ssh-ng://${buildUser}@${hostName}"))
(lib.filter (s: s != "ssh-ng://${buildUser}@${config.networking.hostName}"))
];
trusted-public-keys = lib.pipe buildServerDevices [
(lib.mapAttrsToList (_: v: v.distributedBuilds.storeSigningPublicKey or null))
(builtins.filter (k: k != null))
];
secret-key-files =
let
thisDevice = devices.${config.networking.hostName} or { };
in
lib.optional (thisDevice.distributedBuilds.isBuilder or false) "/etc/nix/signing-key.sec";
max-jobs = (devices.${config.networking.hostName}.distributedBuilds or { }).maxJobs or "auto";
cores = 0;
min-free = 10 * 1024 * 1024;
max-free = 200 * 1024 * 1024;
};
};
systemd.services.nix-daemon.serviceConfig = {
MemoryAccounting = true;
MemoryMax = "90%";
OOMScoreAdjust = 500;
};
};
}