From bf1d9beec1e5a05a7a88c11a5475b921997f46fa Mon Sep 17 00:00:00 2001
From: Daniel Barlow <dan@telent.net>
Date: Sat, 22 Jul 2023 23:22:45 +0100
Subject: [PATCH] add first version of ntp module

---
 examples/rotuer.nix       | 15 +++-----
 modules/ntp/default.nix   | 19 ++++++++++
 modules/ntp/service.nix   | 75 +++++++++++++++++++++++++++++++++++++++
 vanilla-configuration.nix | 14 +++-----
 4 files changed, 103 insertions(+), 20 deletions(-)
 create mode 100644 modules/ntp/default.nix
 create mode 100644 modules/ntp/service.nix

diff --git a/examples/rotuer.nix b/examples/rotuer.nix
index 7c0c23a..8ec9695 100644
--- a/examples/rotuer.nix
+++ b/examples/rotuer.nix
@@ -38,6 +38,7 @@ in rec {
     ../modules/firewall
     ../modules/hostapd
     ../modules/bridge
+    ../modules/ntp
   ];
   rootfsType = "jffs2";
   hostname = "rotuer";
@@ -95,16 +96,10 @@ in rec {
     ];
   };
 
-  services.ntp =
-    let config = writeText "chrony.conf" ''
-      pool pool.ntp.org iburst
-      dumpdir /run/chrony
-      makestep 1.0 3
-    '';
-    in longrun {
-      name = "ntp";
-      run = "${pkgs.chrony}/bin/chronyd -f ${config} -d";
-    };
+  services.ntp = svc.ntp {
+    pools = { "pool.ntp.org" = ["iburst"]; };
+    makestep = { threshold = 1.0; limit = 3; };
+  };
 
   services.sshd = longrun {
     name = "sshd";
diff --git a/modules/ntp/default.nix b/modules/ntp/default.nix
new file mode 100644
index 0000000..2a4e6b3
--- /dev/null
+++ b/modules/ntp/default.nix
@@ -0,0 +1,19 @@
+{ lib, pkgs, config, ...}:
+let
+  inherit (lib) mkOption types;
+in {
+  options = {
+    system.service.ntp = mkOption {
+      type = types.functionTo types.package;
+    };
+  };
+  config = {
+    system.service.ntp = pkgs.callPackage ./service.nix {};
+    users.ntp = {
+      uid = 52; gid= 52; gecos = "Unprivileged NTP user";
+      dir = "/run/ntp";
+      shell = "/bin/false";
+    };
+    # groups.system.usernames = ["ntp"];
+  };
+}
diff --git a/modules/ntp/service.nix b/modules/ntp/service.nix
new file mode 100644
index 0000000..6b2b6e4
--- /dev/null
+++ b/modules/ntp/service.nix
@@ -0,0 +1,75 @@
+{
+  liminix
+, chrony
+, serviceFns
+, lib
+, writeText
+}:
+let
+  inherit (liminix.services) longrun;
+  inherit (lib) concatStringsSep mapAttrsToList;
+  inherit (liminix.lib) typeChecked;
+  inherit (lib) mkOption types;
+
+  serverOpts = types.listOf types.str;
+  t = {
+    user = mkOption {
+      type = types.str;
+      default = "ntp";
+    };
+    servers = mkOption { type = types.attrsOf serverOpts; default = {}; };
+    pools = mkOption { type = types.attrsOf serverOpts; default = {}; };
+    peers = mkOption { type = types.attrsOf serverOpts; default = {}; };
+    makestep = {
+      threshold = mkOption { type = types.number; };
+      limit = mkOption { type = types.number; };
+    };
+    allow = mkOption {
+      description = "subnets from which NTP clients are allowed to access the server";
+      type = types.listOf types.str;
+      default = [];
+    };
+    bindaddress = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+    };
+    binddevice = mkOption {
+      type = types.nullOr types.str;
+      default = null;
+    };
+    dumpdir = mkOption {
+      internal = true;
+      type = types.path;
+      default = "/run/chrony";
+    };
+    extraConfig = mkOption {
+      type = types.lines;
+      default = "";
+    };
+  };
+  configFile = p:
+    (mapAttrsToList (name: opts: "server ${name} ${concatStringsSep "" opts}")
+      p.servers)
+    ++
+    (mapAttrsToList (name: opts: "pool ${name} ${concatStringsSep "" opts}")
+      p.pools)
+    ++
+    (mapAttrsToList (name: opts: "peer ${name} ${concatStringsSep "" opts}")
+      p.peers)
+    ++ [ "user #{p.user}" ]
+    ++ (lib.optional (p.makestep != null) "makestep ${toString p.makestep.threshold} ${toString p.makestep.limit}")
+    ++ (map (n: "allow ${n}") p.allow)
+    ++ (lib.optional (p.bindaddress != null) "bindaddress ${p.bindaddress}")
+    ++ (lib.optional (p.binddevice != null) "binddevice ${p.binddevice}")
+    ++ (lib.optional (p.dumpdir != null) "dumpdir ${p.dumpdir}")
+    ++ [p.extraConfig];
+in
+params:
+let
+  config = writeText "chrony.conf"
+    (concatStringsSep "\n"
+      (configFile (typeChecked "" t params)));
+in longrun {
+  name = "ntp"; # bad name, needs to be unique
+  run = "${chrony}/bin/chronyd -f ${config} -d";
+}
diff --git a/vanilla-configuration.nix b/vanilla-configuration.nix
index c8ebc56..29c5731 100644
--- a/vanilla-configuration.nix
+++ b/vanilla-configuration.nix
@@ -7,6 +7,7 @@ in rec {
   imports = [
     ./modules/tftpboot.nix
     ./modules/wlan.nix
+    ./modules/ntp
   ];
   services.loopback = config.hardware.networkInterfaces.lo;
 
@@ -36,16 +37,9 @@ in rec {
       dependencies = [iface];
     };
 
-  services.ntp =
-    let config = writeText "chrony.conf" ''
-      pool pool.ntp.org iburst
-      dumpdir /run/chrony
-      makestep 1.0 3
-    '';
-    in longrun {
-      name = "ntp";
-      run = "${pkgs.chrony}/bin/chronyd -f ${config} -d";
-    };
+  services.ntp = config.system.service.ntp {
+    pools = { "pool.ntp.org" = ["iburst"] ; };
+  };
 
   services.default = target {
     name = "default";