1 files changed, 90 insertions, 0 deletions
diff --git a/nixos/modules/services/networking/ntpd.nix b/nixos/modules/services/networking/ntpd.nix
new file mode 100644
index 00000000000..e5e164021d3
--- /dev/null
+++ b/nixos/modules/services/networking/ntpd.nix
@@ -0,0 +1,90 @@
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  inherit (pkgs) ntp;
+
+  stateDir = "/var/lib/ntp";
+
+  ntpUser = "ntp";
+
+  configFile = pkgs.writeText "ntp.conf" ''
+    # Keep the drift file in ${stateDir}/ntp.drift.  However, since we
+    # chroot to ${stateDir}, we have to specify it as /ntp.drift.
+    driftfile /ntp.drift
+
+    ${toString (map (server: "server " + server + " iburst\n") config.services.ntp.servers)}
+  '';
+
+  ntpFlags = "-c ${configFile} -u ${ntpUser}:nogroup -i ${stateDir}";
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.ntp = {
+
+      enable = mkOption {
+        default = true;
+        description = ''
+          Whether to synchronise your machine's time using the NTP
+          protocol.
+        '';
+      };
+
+      servers = mkOption {
+        default = [
+          "0.pool.ntp.org"
+          "1.pool.ntp.org"
+          "2.pool.ntp.org"
+        ];
+        description = ''
+          The set of NTP servers from which to synchronise.
+        '';
+      };
+
+    };
+
+  };
+
+
+  ###### implementation
+
+  config = mkIf config.services.ntp.enable {
+
+    # Make tools such as ntpq available in the system path
+    environment.systemPackages = [ pkgs.ntp ];
+
+    users.extraUsers = singleton
+      { name = ntpUser;
+        uid = config.ids.uids.ntp;
+        description = "NTP daemon user";
+        home = stateDir;
+      };
+
+    jobs.ntpd =
+      { description = "NTP Daemon";
+
+        wantedBy = [ "ip-up.target" ];
+        partOf = [ "ip-up.target" ];
+
+        path = [ ntp ];
+
+        preStart =
+          ''
+            mkdir -m 0755 -p ${stateDir}
+            chown ${ntpUser} ${stateDir}
+          '';
+
+        exec = "ntpd -g -n ${ntpFlags}";
+      };
+
+  };
+
+}