nixpkgs/nixos/modules/services/networking/dhcpd.nix
Emery Hemingway a8780387ba nixos/dhcpd: make authoritative mode optional
There are circumstances where running secondary DHCP servers in
non-authoritative mode is advantageous. Retain the previous
authoritative behavior as a default.
2020-07-25 16:33:04 +02:00

225 lines
5.5 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg4 = config.services.dhcpd4;
cfg6 = config.services.dhcpd6;
writeConfig = cfg: pkgs.writeText "dhcpd.conf"
''
default-lease-time 600;
max-lease-time 7200;
${optionalString (!cfg.authoritative) "not "}authoritative;
ddns-update-style interim;
log-facility local1; # see dhcpd.nix
${cfg.extraConfig}
${lib.concatMapStrings
(machine: ''
host ${machine.hostName} {
hardware ethernet ${machine.ethernetAddress};
fixed-address ${machine.ipAddress};
}
'')
cfg.machines
}
'';
dhcpdService = postfix: cfg: optionalAttrs cfg.enable {
"dhcpd${postfix}" = {
description = "DHCPv${postfix} server";
wantedBy = [ "multi-user.target" ];
after = [ "network.target" ];
preStart = ''
mkdir -m 755 -p ${cfg.stateDir}
chown dhcpd:nogroup ${cfg.stateDir}
touch ${cfg.stateDir}/dhcpd.leases
'';
serviceConfig =
let
configFile = if cfg.configFile != null then cfg.configFile else writeConfig cfg;
args = [ "@${pkgs.dhcp}/sbin/dhcpd" "dhcpd${postfix}" "-${postfix}"
"-pf" "/run/dhcpd${postfix}/dhcpd.pid"
"-cf" "${configFile}"
"-lf" "${cfg.stateDir}/dhcpd.leases"
"-user" "dhcpd" "-group" "nogroup"
] ++ cfg.extraFlags
++ cfg.interfaces;
in {
ExecStart = concatMapStringsSep " " escapeShellArg args;
Type = "forking";
Restart = "always";
RuntimeDirectory = [ "dhcpd${postfix}" ];
PIDFile = "/run/dhcpd${postfix}/dhcpd.pid";
};
};
};
machineOpts = { ... }: {
options = {
hostName = mkOption {
type = types.str;
example = "foo";
description = ''
Hostname which is assigned statically to the machine.
'';
};
ethernetAddress = mkOption {
type = types.str;
example = "00:16:76:9a:32:1d";
description = ''
MAC address of the machine.
'';
};
ipAddress = mkOption {
type = types.str;
example = "192.168.1.10";
description = ''
IP address of the machine.
'';
};
};
};
dhcpConfig = postfix: {
enable = mkOption {
type = types.bool;
default = false;
description = ''
Whether to enable the DHCPv${postfix} server.
'';
};
stateDir = mkOption {
type = types.path;
# We use /var/lib/dhcp for DHCPv4 to save backwards compatibility.
default = "/var/lib/dhcp${if postfix == "4" then "" else postfix}";
description = ''
State directory for the DHCP server.
'';
};
extraConfig = mkOption {
type = types.lines;
default = "";
example = ''
option subnet-mask 255.255.255.0;
option broadcast-address 192.168.1.255;
option routers 192.168.1.5;
option domain-name-servers 130.161.158.4, 130.161.33.17, 130.161.180.1;
option domain-name "example.org";
subnet 192.168.1.0 netmask 255.255.255.0 {
range 192.168.1.100 192.168.1.200;
}
'';
description = ''
Extra text to be appended to the DHCP server configuration
file. Currently, you almost certainly need to specify something
there, such as the options specifying the subnet mask, DNS servers,
etc.
'';
};
extraFlags = mkOption {
type = types.listOf types.str;
default = [];
description = ''
Additional command line flags to be passed to the dhcpd daemon.
'';
};
configFile = mkOption {
type = types.nullOr types.path;
default = null;
description = ''
The path of the DHCP server configuration file. If no file
is specified, a file is generated using the other options.
'';
};
interfaces = mkOption {
type = types.listOf types.str;
default = ["eth0"];
description = ''
The interfaces on which the DHCP server should listen.
'';
};
machines = mkOption {
type = with types; listOf (submodule machineOpts);
default = [];
example = [
{ hostName = "foo";
ethernetAddress = "00:16:76:9a:32:1d";
ipAddress = "192.168.1.10";
}
{ hostName = "bar";
ethernetAddress = "00:19:d1:1d:c4:9a";
ipAddress = "192.168.1.11";
}
];
description = ''
A list mapping Ethernet addresses to IPv${postfix} addresses for the
DHCP server.
'';
};
authoritative = mkOption {
type = types.bool;
default = true;
description = ''
Whether the DHCP server shall send DHCPNAK messages to misconfigured
clients. If this is not done, clients may be unable to get a correct
IP address after changing subnets until their old lease has expired.
'';
};
};
in
{
imports = [
(mkRenamedOptionModule [ "services" "dhcpd" ] [ "services" "dhcpd4" ])
];
###### interface
options = {
services.dhcpd4 = dhcpConfig "4";
services.dhcpd6 = dhcpConfig "6";
};
###### implementation
config = mkIf (cfg4.enable || cfg6.enable) {
users = {
users.dhcpd = {
uid = config.ids.uids.dhcpd;
description = "DHCP daemon user";
};
};
systemd.services = dhcpdService "4" cfg4 // dhcpdService "6" cfg6;
};
}