nixpkgs/nixos/modules/config/networking.nix
William A. Kennington III c234e7b115 nixos/networking: Rebuild resolvconf during activation
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.
2014-11-26 11:22:02 -08:00

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# /etc files related to networking, such as /etc/services.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.networking;
dnsmasqResolve = config.services.dnsmasq.enable &&
config.services.dnsmasq.resolveLocalQueries;
hasLocalResolver = config.services.bind.enable || dnsmasqResolve;
in
{
options = {
networking.extraHosts = lib.mkOption {
type = types.lines;
default = "";
example = "192.168.0.1 lanlocalhost";
description = ''
Additional entries to be appended to <filename>/etc/hosts</filename>.
'';
};
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.
'';
};
};
config = {
environment.etc =
{ # /etc/services: TCP/UDP port assignments.
"services".source = pkgs.iana_etc + "/etc/services";
# /etc/protocols: IP protocol numbers.
"protocols".source = pkgs.iana_etc + "/etc/protocols";
# /etc/rpc: RPC program numbers.
"rpc".source = pkgs.glibc + "/etc/rpc";
# /etc/hosts: Hostname-to-IP mappings.
"hosts".text =
''
127.0.0.1 localhost
${optionalString cfg.enableIPv6 ''
::1 localhost
''}
${cfg.extraHosts}
'';
# /etc/resolvconf.conf: Configuration for openresolv.
"resolvconf.conf".text =
''
# This is the default, but we must set it here to prevent
# a collision with an apparently unrelated environment
# variable with the same name exported by dhcpcd.
interface_order='lo lo[0-9]*'
'' + optionalString config.services.nscd.enable ''
# Invalidate the nscd cache whenever resolv.conf is
# regenerated.
libc_restart='${pkgs.systemd}/bin/systemctl try-restart --no-block nscd.service'
'' + optionalString cfg.dnsSingleRequest ''
# only send one DNS request at a time
resolv_conf_options='single-request'
'' + 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
'';
} // (optionalAttrs config.services.resolved.enable (
if dnsmasqResolve then {
"dnsmasq-resolv.conf".source = "/run/systemd/resolve/resolv.conf";
} else {
"resolv.conf".source = "/run/systemd/resolve/resolv.conf";
}
));
# The ip-up target is started when we have IP connectivity. So
# services that depend on IP connectivity (like ntpd) should be
# pulled in by this target.
systemd.targets.ip-up.description = "Services Requiring IP Connectivity";
# 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" "tmpfs" "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
${pkgs.openresolv}/bin/resolvconf -u
'';
};
}