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|
# Systemd services for libvirtd.
{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.virtualisation.libvirtd;
vswitch = config.virtualisation.vswitch;
configFile = pkgs.writeText "libvirtd.conf" ''
unix_sock_group = "libvirtd"
unix_sock_rw_perms = "0770"
auth_unix_ro = "none"
auth_unix_rw = "none"
${cfg.extraConfig}
'';
in
{
###### interface
options = {
virtualisation.libvirtd.enable =
mkOption {
type = types.bool;
default = false;
description =
''
This option enables libvirtd, a daemon that manages
virtual machines. Users in the "libvirtd" group can interact with
the daemon (e.g. to start or stop VMs) using the
<command>virsh</command> command line tool, among others.
'';
};
virtualisation.libvirtd.enableKVM =
mkOption {
type = types.bool;
default = true;
description =
''
This option enables support for QEMU/KVM in libvirtd.
'';
};
virtualisation.libvirtd.extraConfig =
mkOption {
type = types.lines;
default = "";
description =
''
Extra contents appended to the libvirtd configuration file,
libvirtd.conf.
'';
};
virtualisation.libvirtd.extraOptions =
mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "--verbose" ];
description =
''
Extra command line arguments passed to libvirtd on startup.
'';
};
virtualisation.libvirtd.onShutdown =
mkOption {
type = types.enum ["shutdown" "suspend" ];
default = "suspend";
description =
''
When shutting down / restarting the host what method should
be used to gracefully halt the guests. Setting to "shutdown"
will cause an ACPI shutdown of each guest. "suspend" will
attempt to save the state of the guests ready to restore on boot.
'';
};
};
###### implementation
config = mkIf cfg.enable {
environment.systemPackages =
[ pkgs.libvirt pkgs.netcat-openbsd ]
++ optional cfg.enableKVM pkgs.qemu_kvm;
boot.kernelModules = [ "tun" ];
systemd.services.libvirtd =
{ description = "Libvirt Virtual Machine Management Daemon";
wantedBy = [ "multi-user.target" ];
after = [ "systemd-udev-settle.service" ]
++ optional vswitch.enable "vswitchd.service";
path = [
pkgs.bridge-utils
pkgs.dmidecode
pkgs.dnsmasq
pkgs.ebtables
]
++ optional cfg.enableKVM pkgs.qemu_kvm
++ optional vswitch.enable vswitch.package;
preStart =
''
mkdir -p /var/log/libvirt/qemu -m 755
rm -f /var/run/libvirtd.pid
mkdir -p /var/lib/libvirt
mkdir -p /var/lib/libvirt/dnsmasq
chmod 755 /var/lib/libvirt
chmod 755 /var/lib/libvirt/dnsmasq
# Libvirt unfortunately writes mutable state (such as
# runtime changes to VM, network or filter configurations)
# to /etc. So we can't use environment.etc to make the
# default network and filter definitions available, since
# libvirt will then modify the originals in the Nix store.
# So here we copy them instead. Ugly.
for i in $(cd ${pkgs.libvirt}/etc && echo \
libvirt/qemu/networks/*.xml libvirt/qemu/networks/autostart/*.xml \
libvirt/nwfilter/*.xml );
do
mkdir -p /etc/$(dirname $i) -m 755
cp -fpd ${pkgs.libvirt}/etc/$i /etc/$i
done
# libvirtd puts the full path of the emulator binary in the machine
# config file. But this path can unfortunately be garbage collected
# while still being used by the virtual machine. So update the
# emulator path on each startup to something valid (re-scan $PATH).
for file in /etc/libvirt/qemu/*.xml /etc/libvirt/lxc/*.xml; do
test -f "$file" || continue
# get (old) emulator path from config file
emulator=$(grep "^[[:space:]]*<emulator>" "$file" | sed 's,^[[:space:]]*<emulator>\(.*\)</emulator>.*,\1,')
# get a (definitely) working emulator path by re-scanning $PATH
new_emulator=$(PATH=${pkgs.libvirt}/libexec:$PATH command -v $(basename "$emulator"))
# write back
sed -i "s,^[[:space:]]*<emulator>.*, <emulator>$new_emulator</emulator> <!-- WARNING: emulator dirname is auto-updated by the nixos libvirtd module -->," "$file"
done
''; # */
serviceConfig.ExecStart = ''@${pkgs.libvirt}/sbin/libvirtd libvirtd --config "${configFile}" --daemon ${concatStringsSep " " cfg.extraOptions}'';
serviceConfig.Type = "forking";
serviceConfig.KillMode = "process"; # when stopping, leave the VMs alone
# Wait until libvirtd is ready to accept requests.
postStart =
''
for ((i = 0; i < 60; i++)); do
if ${pkgs.libvirt}/bin/virsh list > /dev/null; then exit 0; fi
sleep 1
done
exit 1 # !!! seems to be ignored
'';
};
jobs."libvirt-guests" =
{ description = "Libvirt Virtual Machines";
wantedBy = [ "multi-user.target" ];
wants = [ "libvirtd.service" ];
after = [ "libvirtd.service" ];
restartIfChanged = false;
path = [ pkgs.gettext pkgs.libvirt pkgs.gawk ];
preStart =
''
mkdir -p /var/lock/subsys -m 755
${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests start || true
'';
postStop =
''
export PATH=${pkgs.gettext}/bin:$PATH
export ON_SHUTDOWN=${cfg.onShutdown}
${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests stop
'';
serviceConfig.Type = "oneshot";
serviceConfig.RemainAfterExit = true;
};
users.extraGroups.libvirtd.gid = config.ids.gids.libvirtd;
};
}
|