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resolvconf service: init

This is a refactor of how resolvconf is managed on NixOS. We split it
into a separate service which is enabled internally depending on whether
we want /etc/resolv.conf to be managed by it. Various services now take
advantage of those configuration options.

We also now use systemd instead of activation scripts to update
resolv.conf.

NetworkManager now uses the right option for rc-manager DNS
automatically, so the configuration option shouldn't be exposed.
This commit is contained in:
Nikolay Amiantov 2019-07-15 20:18:49 +03:00
parent 267c8d6b2f
commit 01b90dce78
13 changed files with 216 additions and 145 deletions

View file

@ -7,16 +7,6 @@ with lib;
let
cfg = config.networking;
dnsmasqResolve = config.services.dnsmasq.enable &&
config.services.dnsmasq.resolveLocalQueries;
hasLocalResolver = config.services.bind.enable ||
config.services.unbound.enable ||
dnsmasqResolve;
resolvconfOptions = cfg.resolvconfOptions
++ optional cfg.dnsSingleRequest "single-request"
++ optional cfg.dnsExtensionMechanism "edns0";
localhostMapped4 = cfg.hosts ? "127.0.0.1" && elem "localhost" cfg.hosts."127.0.0.1";
localhostMapped6 = cfg.hosts ? "::1" && elem "localhost" cfg.hosts."::1";
@ -64,48 +54,6 @@ in
'';
};
networking.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.
'';
};
networking.dnsExtensionMechanism = lib.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.
'';
};
networking.extraResolvconfConf = lib.mkOption {
type = types.lines;
default = "";
example = "libc=NO";
description = ''
Extra configuration to append to <filename>resolvconf.conf</filename>.
'';
};
networking.resolvconfOptions = lib.mkOption {
type = types.listOf types.str;
default = [];
example = [ "ndots:1" "rotate" ];
description = ''
Set the options in <filename>/etc/resolv.conf</filename>.
'';
};
networking.timeServers = mkOption {
default = [
"0.nixos.pool.ntp.org"
@ -240,35 +188,6 @@ in
# /etc/host.conf: resolver configuration file
"host.conf".text = cfg.hostConf;
# /etc/resolvconf.conf: Configuration for openresolv.
"resolvconf.conf".text =
''
# 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 hasLocalResolver ''
# This hosts runs a full-blown DNS resolver.
name_servers='127.0.0.1'
'' + optionalString dnsmasqResolve ''
dnsmasq_conf=/etc/dnsmasq-conf.conf
dnsmasq_resolv=/etc/dnsmasq-resolv.conf
'' + cfg.extraResolvconfConf + ''
'';
} // optionalAttrs config.services.resolved.enable {
# symlink the dynamic stub resolver of resolv.conf as recommended by upstream:
# https://www.freedesktop.org/software/systemd/man/systemd-resolved.html#/etc/resolv.conf
"resolv.conf".source = "/run/systemd/resolve/stub-resolv.conf";
} // optionalAttrs (config.services.resolved.enable && dnsmasqResolve) {
"dnsmasq-resolv.conf".source = "/run/systemd/resolve/resolv.conf";
} // optionalAttrs (pkgs.stdenv.hostPlatform.libc == "glibc") {
# /etc/rpc: RPC program numbers.
"rpc".source = pkgs.glibc.out + "/etc/rpc";
@ -295,29 +214,6 @@ in
# Install the proxy environment variables
environment.sessionVariables = cfg.proxy.envVars;
# This is needed when /etc/resolv.conf is being overriden by networkd
# and other configurations. If the file is destroyed by an environment
# activation then it must be rebuilt so that applications which interface
# with /etc/resolv.conf directly don't break.
system.activationScripts.resolvconf = stringAfter [ "etc" "specialfs" "var" ]
''
# Systemd resolved controls its own resolv.conf
rm -f /run/resolvconf/interfaces/systemd
${optionalString config.services.resolved.enable ''
rm -rf /run/resolvconf/interfaces
mkdir -p /run/resolvconf/interfaces
ln -s /run/systemd/resolve/resolv.conf /run/resolvconf/interfaces/systemd
''}
# Make sure resolv.conf is up to date if not managed manually, by systemd or
# by NetworkManager
${optionalString (!config.environment.etc?"resolv.conf" &&
(cfg.networkmanager.enable ->
cfg.networkmanager.rc-manager == "resolvconf")) ''
${pkgs.openresolv}/bin/resolvconf -u
''}
'';
};
}