diff options
Diffstat (limited to 'nixpkgs/nixos/modules/config/resolvconf.nix')
-rw-r--r-- | nixpkgs/nixos/modules/config/resolvconf.nix | 149 |
1 files changed, 149 insertions, 0 deletions
diff --git a/nixpkgs/nixos/modules/config/resolvconf.nix b/nixpkgs/nixos/modules/config/resolvconf.nix new file mode 100644 index 000000000000..406c6a7ac329 --- /dev/null +++ b/nixpkgs/nixos/modules/config/resolvconf.nix @@ -0,0 +1,149 @@ +# /etc files related to networking, such as /etc/services. + +{ config, lib, pkgs, ... }: + +with lib; + +let + + cfg = config.networking.resolvconf; + + resolvconfOptions = cfg.extraOptions + ++ optional cfg.dnsSingleRequest "single-request" + ++ optional cfg.dnsExtensionMechanism "edns0"; + + configText = + '' + # This is the default, but we must set it here to prevent + # a collision with an apparently unrelated environment + # variable with the same name exported by dhcpcd. + interface_order='lo lo[0-9]*' + '' + optionalString config.services.nscd.enable '' + # Invalidate the nscd cache whenever resolv.conf is + # regenerated. + libc_restart='${pkgs.systemd}/bin/systemctl try-restart --no-block nscd.service 2> /dev/null' + '' + optionalString (length resolvconfOptions > 0) '' + # Options as described in resolv.conf(5) + resolv_conf_options='${concatStringsSep " " resolvconfOptions}' + '' + optionalString cfg.useLocalResolver '' + # This hosts runs a full-blown DNS resolver. + name_servers='127.0.0.1' + '' + cfg.extraConfig; + +in + +{ + + options = { + + networking.resolvconf = { + + enable = mkOption { + type = types.bool; + default = false; + internal = true; + description = '' + DNS configuration is managed by resolvconf. + ''; + }; + + useHostResolvConf = mkOption { + type = types.bool; + default = false; + description = '' + In containers, whether to use the + <filename>resolv.conf</filename> supplied by the host. + ''; + }; + + dnsSingleRequest = lib.mkOption { + type = types.bool; + default = false; + description = '' + Recent versions of glibc will issue both ipv4 (A) and ipv6 (AAAA) + address queries at the same time, from the same port. Sometimes upstream + routers will systemically drop the ipv4 queries. The symptom of this problem is + that 'getent hosts example.com' only returns ipv6 (or perhaps only ipv4) addresses. The + workaround for this is to specify the option 'single-request' in + /etc/resolv.conf. This option enables that. + ''; + }; + + dnsExtensionMechanism = mkOption { + type = types.bool; + default = true; + description = '' + Enable the <code>edns0</code> option in <filename>resolv.conf</filename>. With + that option set, <code>glibc</code> supports use of the extension mechanisms for + DNS (EDNS) specified in RFC 2671. The most popular user of that feature is DNSSEC, + which does not work without it. + ''; + }; + + extraConfig = mkOption { + type = types.lines; + default = ""; + example = "libc=NO"; + description = '' + Extra configuration to append to <filename>resolvconf.conf</filename>. + ''; + }; + + extraOptions = mkOption { + type = types.listOf types.str; + default = []; + example = [ "ndots:1" "rotate" ]; + description = '' + Set the options in <filename>/etc/resolv.conf</filename>. + ''; + }; + + useLocalResolver = mkOption { + type = types.bool; + default = false; + description = '' + Use local DNS server for resolving. + ''; + }; + + }; + + }; + + config = mkMerge [ + { + networking.resolvconf.enable = !(config.environment.etc ? "resolv.conf"); + + environment.etc."resolvconf.conf".text = + if !cfg.enable then + # Force-stop any attempts to use resolvconf + '' + echo "resolvconf is disabled on this system but was used anyway:" >&2 + echo "$0 $*" >&2 + exit 1 + '' + else configText; + } + + (mkIf cfg.enable { + environment.systemPackages = [ pkgs.openresolv ]; + + systemd.services.resolvconf = { + description = "resolvconf update"; + + before = [ "network-pre.target" ]; + wants = [ "network-pre.target" ]; + wantedBy = [ "multi-user.target" ]; + restartTriggers = [ config.environment.etc."resolvconf.conf".source ]; + + serviceConfig = { + Type = "oneshot"; + ExecStart = "${pkgs.openresolv}/bin/resolvconf -u"; + RemainAfterExit = true; + }; + }; + + }) + ]; + +} |