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

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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.services.dnscache;
dnscache-root = pkgs.runCommand "dnscache-root" { preferLocalBuild = true; } ''
mkdir -p $out/{servers,ip}
${concatMapStrings (ip: ''
touch "$out/ip/"${lib.escapeShellArg ip}
'') cfg.clientIps}
${concatStrings (mapAttrsToList (host: ips: ''
${concatMapStrings (ip: ''
echo ${lib.escapeShellArg ip} >> "$out/servers/"${lib.escapeShellArg host}
'') ips}
'') cfg.domainServers)}
# if a list of root servers was not provided in config, copy it
# over. (this is also done by dnscache-conf, but we 'rm -rf
# /var/lib/dnscache/root' below & replace it wholesale with this,
# so we have to ensure servers/@ exists ourselves.)
if [ ! -e $out/servers/@ ]; then
# symlink does not work here, due chroot
cp ${pkgs.djbdns}/etc/dnsroots.global $out/servers/@;
fi
'';
in {
###### interface
options = {
services.dnscache = {
enable = mkOption {
default = false;
type = types.bool;
description = "Whether to run the dnscache caching dns server.";
};
ip = mkOption {
default = "0.0.0.0";
type = types.str;
description = "IP address on which to listen for connections.";
};
clientIps = mkOption {
default = [ "127.0.0.1" ];
type = types.listOf types.str;
description = "Client IP addresses (or prefixes) from which to accept connections.";
example = ["192.168" "172.23.75.82"];
};
domainServers = mkOption {
default = { };
type = types.attrsOf (types.listOf types.str);
description = ''
Table of {hostname: server} pairs to use as authoritative servers for hosts (and subhosts).
If entry for @ is not specified predefined list of root servers is used.
'';
example = literalExample ''
{
"@" = ["8.8.8.8" "8.8.4.4"];
"example.com" = ["192.168.100.100"];
}
'';
};
forwardOnly = mkOption {
default = false;
type = types.bool;
description = ''
Whether to treat root servers (for @) as caching
servers, requesting addresses the same way a client does. This is
needed if you want to use e.g. Google DNS as your upstream DNS.
'';
};
};
};
###### implementation
config = mkIf config.services.dnscache.enable {
environment.systemPackages = [ pkgs.djbdns ];
2019-10-12 20:25:28 +00:00
users.users.dnscache.isSystemUser = true;
systemd.services.dnscache = {
description = "djbdns dnscache server";
wantedBy = [ "multi-user.target" ];
path = with pkgs; [ bash daemontools djbdns ];
preStart = ''
rm -rf /var/lib/dnscache
dnscache-conf dnscache dnscache /var/lib/dnscache ${config.services.dnscache.ip}
rm -rf /var/lib/dnscache/root
ln -sf ${dnscache-root} /var/lib/dnscache/root
'';
script = ''
cd /var/lib/dnscache/
${optionalString cfg.forwardOnly "export FORWARDONLY=1"}
exec ./run
'';
};
};
}