nixpkgs/nixos/modules/services/networking/dhcpd.nix

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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.dhcpd;
stateDir = "/var/lib/dhcp"; # Don't use /var/state/dhcp; not FHS-compliant.
configFile = if cfg.configFile != null then cfg.configFile else pkgs.writeText "dhcpd.conf"
''
default-lease-time 600;
max-lease-time 7200;
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
}
'';
in
{
###### interface
options = {
services.dhcpd = {
enable = mkOption {
default = false;
description = "
Whether to enable the DHCP server.
";
};
extraConfig = mkOption {
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 here, such as the options specifying the subnet
mask, DNS servers, etc.
";
};
configFile = mkOption {
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 {
default = ["eth0"];
description = "
The interfaces on which the DHCP server should listen.
";
};
machines = mkOption {
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 IP addresses for the
DHCP server.
";
};
};
};
###### implementation
config = mkIf config.services.dhcpd.enable {
users = {
extraUsers.dhcpd = {
uid = config.ids.uids.dhcpd;
description = "DHCP daemon user";
};
};
systemd.services.dhcpd =
{ description = "DHCP server";
wantedBy = [ "multi-user.target" ];
after = [ "network.target" ];
path = [ pkgs.dhcp ];
preStart =
''
mkdir -m 755 -p ${stateDir}
touch ${stateDir}/dhcpd.leases
mkdir -m 755 -p /run/dhcpd
chown dhcpd /run/dhcpd
'';
serviceConfig =
{ ExecStart = "@${pkgs.dhcp}/sbin/dhcpd dhcpd"
+ " -pf /run/dhcpd/dhcpd.pid -cf ${configFile}"
+ " -lf ${stateDir}/dhcpd.leases -user dhcpd -group nogroup"
+ " ${toString cfg.interfaces}";
Restart = "always";
Type = "forking";
PIDFile = "/run/dhcpd/dhcpd.pid";
};
};
};
}