nix-files/modules/services/dyn-dns.nix

121 lines
3.6 KiB
Nix

{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.sane.services.dyn-dns;
getIp = pkgs.writeShellScript "dyn-dns-query-wan" ''
# preferred method and fallback
# OPNsense router broadcasts its UPnP endpoint every 30s
timeout 60 ${pkgs.sane-scripts.ip-check}/bin/sane-ip-check --json || \
${pkgs.sane-scripts.ip-check}/bin/sane-ip-check --json --no-upnp
'';
in
{
options = {
sane.services.dyn-dns = {
enable = mkOption {
default = false;
type = types.bool;
};
ipPath = mkOption {
default = "/var/lib/uninsane/wan.txt";
type = types.str;
description = "where to store the latest WAN IPv4 address";
};
upnpPath = mkOption {
default = "/var/lib/uninsane/upnp.txt";
type = types.str;
description = ''
where to store the address of the UPNP device (if any) that can be used to create port forwards.
'';
};
ipCmd = mkOption {
default = "${getIp}";
type = types.path;
description = "command to run to query the current WAN IP";
};
interval = mkOption {
type = types.str;
default = "10min";
description = "systemd time string for how frequently to re-check the IP";
};
restartOnChange = mkOption {
type = types.listOf types.str;
default = [];
description = "list of systemd unit files to restart when the IP changes";
};
};
};
config = mkIf cfg.enable {
systemd.services.dyn-dns = {
description = "update this host's record of its WAN IP";
serviceConfig.Type = "oneshot";
restartTriggers = [(builtins.toJSON cfg)];
after = [ "network.target" ];
wantedBy = cfg.restartOnChange;
before = cfg.restartOnChange;
script = let
jq = "${pkgs.jq}/bin/jq";
sed = "${pkgs.gnused}/bin/sed";
in ''
mkdir -p "$(dirname '${cfg.ipPath}')"
mkdir -p "$(dirname '${cfg.upnpPath}')"
newIpDetails=$(${cfg.ipCmd})
newIp=$(echo "$newIpDetails" | ${jq} ".wan" | ${sed} 's/^"//' | ${sed} 's/"$//')
newUpnp=$(echo "$newIpDetails" | ${jq} ".upnp" | ${sed} 's/^"//' | ${sed} 's/"$//')
oldIp=$(cat '${cfg.ipPath}' || true)
oldUpnp=$(cat '${cfg.upnpPath}' || true)
# systemd path units are triggered on any file write action,
# regardless of content change. so only update the file if our IP *actually* changed
if [ "$newIp" != "$oldIp" -a -n "$newIp" ]
then
echo "$newIp" > '${cfg.ipPath}'
echo "WAN ip changed $oldIp -> $newIp"
fi
if [ "$newUpnp" != "$oldUpnp" -a -n "$newUpnp" ]
then
echo "$newUpnp" > '${cfg.upnpPath}'
echo "UPNP changed $oldUpnp -> $newUpnp"
fi
exit $(test -f '${cfg.ipPath}' -a '${cfg.upnpPath}')
'';
};
systemd.timers.dyn-dns = {
# if anything wants dyn-dns.service, they surely want the timer too.
wantedBy = [ "dyn-dns.service" ];
timerConfig = {
OnUnitActiveSec = cfg.interval;
};
};
systemd.paths.dyn-dns-watcher = {
before = [ "dyn-dns.timer" ];
wantedBy = [ "dyn-dns.timer" ];
pathConfig = {
Unit = "dyn-dns-reactor.service";
PathChanged = [ cfg.ipPath ];
};
};
systemd.services.dyn-dns-reactor = {
description = "react to the system's WAN IP changing";
serviceConfig.Type = "oneshot";
script = if cfg.restartOnChange != [] then ''
${pkgs.systemd}/bin/systemctl restart ${toString cfg.restartOnChange}
'' else "${pkgs.coreutils}/bin/true";
};
};
}