From 02d9a8066a0ad0adbf9d1c3617659a4a00610a88 Mon Sep 17 00:00:00 2001
From: "Ricardo M. Correia" <rcorreia@wizy.org>
Date: Thu, 23 May 2013 02:07:49 +0000
Subject: [PATCH 1/2] Add chrony service Also, do not build and add ntp to the
 system unless it is enabled.

---
 modules/config/system-path.nix         |  1 -
 modules/misc/ids.nix                   |  1 +
 modules/module-list.nix                |  1 +
 modules/services/networking/chrony.nix | 88 ++++++++++++++++++++++++++
 modules/services/networking/ntpd.nix   |  3 +
 5 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 modules/services/networking/chrony.nix

diff --git a/modules/config/system-path.nix b/modules/config/system-path.nix
index 8c36015718c..6e73118fe08 100644
--- a/modules/config/system-path.nix
+++ b/modules/config/system-path.nix
@@ -41,7 +41,6 @@ let
       pkgs.nano
       pkgs.ncurses
       pkgs.netcat
-      pkgs.ntp
       pkgs.openssh
       pkgs.pciutils
       pkgs.perl
diff --git a/modules/misc/ids.nix b/modules/misc/ids.nix
index fd76dfc47a1..8a23148b028 100644
--- a/modules/misc/ids.nix
+++ b/modules/misc/ids.nix
@@ -75,6 +75,7 @@ in
     spamd = 56;
     nslcd = 58;
     nginx = 60;
+    chrony = 61;
 
     # When adding a uid, make sure it doesn't match an existing gid.
 
diff --git a/modules/module-list.nix b/modules/module-list.nix
index b6193b19131..e6b4fd37c66 100644
--- a/modules/module-list.nix
+++ b/modules/module-list.nix
@@ -125,6 +125,7 @@
   ./services/networking/bind.nix
   ./services/networking/bitlbee.nix
   ./services/networking/cntlm.nix
+  ./services/networking/chrony.nix
   ./services/networking/ddclient.nix
   #./services/networking/dhclient.nix
   ./services/networking/dhcpcd.nix
diff --git a/modules/services/networking/chrony.nix b/modules/services/networking/chrony.nix
new file mode 100644
index 00000000000..5a53744791c
--- /dev/null
+++ b/modules/services/networking/chrony.nix
@@ -0,0 +1,88 @@
+{ config, pkgs, ... }:
+
+with pkgs.lib;
+
+let
+
+  inherit (pkgs) chrony;
+
+  stateDir = "/var/lib/chrony";
+
+  chronyUser = "chrony";
+
+  configFile = pkgs.writeText "chrony.conf" ''
+    ${toString (map (server: "server " + server + "\n") config.services.chrony.servers)}
+
+    driftfile ${stateDir}/chrony.drift
+  '';
+
+  chronyFlags = "-m -f ${configFile} -u ${chronyUser}";
+
+in
+
+{
+
+  ###### interface
+
+  options = {
+
+    services.chrony = {
+
+      enable = mkOption {
+        default = false;
+        description = ''
+          Whether to synchronise your machine's time using chrony.
+          Make sure you disable NTP if you enable this service.
+        '';
+      };
+
+      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.chrony.enable {
+
+    # Make chronyc available in the system path
+    environment.systemPackages = [ pkgs.chrony ];
+
+    users.extraUsers = singleton
+      { name = chronyUser;
+        uid = config.ids.uids.chrony;
+        description = "chrony daemon user";
+        home = stateDir;
+      };
+
+    jobs.chronyd =
+      { description = "chrony daemon";
+
+        wantedBy = [ "ip-up.target" ];
+        partOf = [ "ip-up.target" ];
+
+        path = [ chrony ];
+
+        preStart =
+          ''
+            mkdir -m 0755 -p ${stateDir}
+            chown ${chronyUser} ${stateDir}
+          '';
+
+        exec = "chronyd -n ${chronyFlags}";
+      };
+
+  };
+
+}
diff --git a/modules/services/networking/ntpd.nix b/modules/services/networking/ntpd.nix
index be3fcbd6543..e5e164021d3 100644
--- a/modules/services/networking/ntpd.nix
+++ b/modules/services/networking/ntpd.nix
@@ -58,6 +58,9 @@ in
 
   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;

From 6336048c5843ffcbd9fb010e47386adda2cdb913 Mon Sep 17 00:00:00 2001
From: "Ricardo M. Correia" <rcorreia@wizy.org>
Date: Thu, 23 May 2013 03:00:09 +0000
Subject: [PATCH 2/2] chrony: properly set rtconutc option, and add a few more
 options

---
 modules/services/networking/chrony.nix | 32 +++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/modules/services/networking/chrony.nix b/modules/services/networking/chrony.nix
index 5a53744791c..5e9818858e0 100644
--- a/modules/services/networking/chrony.nix
+++ b/modules/services/networking/chrony.nix
@@ -10,10 +10,20 @@ let
 
   chronyUser = "chrony";
 
+  cfg = config.services.chrony;
+
   configFile = pkgs.writeText "chrony.conf" ''
-    ${toString (map (server: "server " + server + "\n") config.services.chrony.servers)}
+    ${toString (map (server: "server " + server + "\n") cfg.servers)}
+
+    ${optionalString cfg.initstepslew.enabled ''
+      initstepslew ${toString cfg.initstepslew.threshold} ${toString (map (server: server + " ") cfg.initstepslew.servers)}
+    ''}
 
     driftfile ${stateDir}/chrony.drift
+
+    ${optionalString (!config.time.hardwareClockInLocalTime) "rtconutc"}
+
+    ${cfg.extraConfig}
   '';
 
   chronyFlags = "-m -f ${configFile} -u ${chronyUser}";
@@ -47,6 +57,26 @@ in
         '';
       };
 
+      initstepslew = mkOption {
+        default = {
+          enabled = true;
+          threshold = 1000; # by default, same threshold as 'ntpd -g' (1000s)
+          servers = cfg.servers;
+        };
+        description = ''
+          Allow chronyd to make a rapid measurement of the system clock error at
+          boot time, and to correct the system clock by stepping before normal
+          operation begins.
+        '';
+      };
+
+      extraConfig = mkOption {
+        default = "";
+        description = ''
+          Extra configuration directives that should be added to
+          <literal>chrony.conf</literal>
+        '';
+      };
     };
 
   };