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nixpkgs/nixos/modules/virtualisation/libvirtd.nix

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{ config, lib, pkgs, ... }:
with lib;
let
cfg = config.virtualisation.libvirtd;
vswitch = config.virtualisation.vswitch;
configFile = pkgs.writeText "libvirtd.conf" ''
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auth_unix_ro = "polkit"
auth_unix_rw = "polkit"
${cfg.extraConfig}
'';
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ovmfFilePrefix = if pkgs.stdenv.isAarch64 then "AAVMF" else "OVMF";
qemuConfigFile = pkgs.writeText "qemu.conf" ''
${optionalString cfg.qemu.ovmf.enable ''
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nvram = [ "/run/libvirt/nix-ovmf/${ovmfFilePrefix}_CODE.fd:/run/libvirt/nix-ovmf/${ovmfFilePrefix}_VARS.fd" ]
''}
${optionalString (!cfg.qemu.runAsRoot) ''
user = "qemu-libvirtd"
group = "qemu-libvirtd"
''}
${cfg.qemu.verbatimConfig}
'';
dirName = "libvirt";
subDirs = list: [ dirName ] ++ map (e: "${dirName}/${e}") list;
ovmfModule = types.submodule {
options = {
enable = mkOption {
type = types.bool;
default = true;
description = ''
Allows libvirtd to take advantage of OVMF when creating new
QEMU VMs with UEFI boot.
'';
};
package = mkOption {
type = types.package;
default = pkgs.OVMF;
defaultText = literalExpression "pkgs.OVMF";
example = literalExpression "pkgs.OVMFFull";
description = ''
OVMF package to use.
'';
};
};
};
swtpmModule = types.submodule {
options = {
enable = mkOption {
type = types.bool;
default = false;
description = ''
Allows libvirtd to use swtpm to create an emulated TPM.
'';
};
package = mkOption {
type = types.package;
default = pkgs.swtpm;
defaultText = literalExpression "pkgs.swtpm";
description = ''
swtpm package to use.
'';
};
};
};
qemuModule = types.submodule {
options = {
package = mkOption {
type = types.package;
default = pkgs.qemu;
defaultText = literalExpression "pkgs.qemu";
description = ''
Qemu package to use with libvirt.
`pkgs.qemu` can emulate alien architectures (e.g. aarch64 on x86)
`pkgs.qemu_kvm` saves disk space allowing to emulate only host architectures.
'';
};
runAsRoot = mkOption {
type = types.bool;
default = true;
description = ''
If true, libvirtd runs qemu as root.
If false, libvirtd runs qemu as unprivileged user qemu-libvirtd.
Changing this option to false may cause file permission issues
for existing guests. To fix these, manually change ownership
of affected files in /var/lib/libvirt/qemu to qemu-libvirtd.
'';
};
verbatimConfig = mkOption {
type = types.lines;
default = ''
namespaces = []
'';
description = ''
Contents written to the qemu configuration file, qemu.conf.
Make sure to include a proper namespace configuration when
supplying custom configuration.
'';
};
ovmf = mkOption {
type = ovmfModule;
default = { };
description = ''
QEMU's OVMF options.
'';
};
swtpm = mkOption {
type = swtpmModule;
default = { };
description = ''
QEMU's swtpm options.
'';
};
};
};
in
{
imports = [
(mkRemovedOptionModule [ "virtualisation" "libvirtd" "enableKVM" ]
"Set the option `virtualisation.libvirtd.qemu.package' instead.")
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuPackage" ]
[ "virtualisation" "libvirtd" "qemu" "package" ])
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuRunAsRoot" ]
[ "virtualisation" "libvirtd" "qemu" "runAsRoot" ])
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuVerbatimConfig" ]
[ "virtualisation" "libvirtd" "qemu" "verbatimConfig" ])
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuOvmf" ]
[ "virtualisation" "libvirtd" "qemu" "ovmf" "enable" ])
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuOvmfPackage" ]
[ "virtualisation" "libvirtd" "qemu" "ovmf" "package" ])
(mkRenamedOptionModule
[ "virtualisation" "libvirtd" "qemuSwtpm" ]
[ "virtualisation" "libvirtd" "qemu" "swtpm" "enable" ])
];
###### 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.
'';
};
package = mkOption {
type = types.package;
default = pkgs.libvirt;
defaultText = literalExpression "pkgs.libvirt";
description = ''
libvirt package to use.
'';
};
extraConfig = mkOption {
type = types.lines;
default = "";
description = ''
Extra contents appended to the libvirtd configuration file,
libvirtd.conf.
'';
};
extraOptions = mkOption {
type = types.listOf types.str;
default = [ ];
example = [ "--verbose" ];
description = ''
Extra command line arguments passed to libvirtd on startup.
'';
};
onBoot = mkOption {
type = types.enum [ "start" "ignore" ];
default = "start";
description = ''
Specifies the action to be done to / on the guests when the host boots.
The "start" option starts all guests that were running prior to shutdown
regardless of their autostart settings. The "ignore" option will not
start the formerly running guest on boot. However, any guest marked as
autostart will still be automatically started by 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.
'';
};
allowedBridges = mkOption {
type = types.listOf types.str;
default = [ "virbr0" ];
description = ''
List of bridge devices that can be used by qemu:///session
'';
};
qemu = mkOption {
type = qemuModule;
default = { };
description = ''
QEMU related options.
'';
};
};
###### implementation
config = mkIf cfg.enable {
assertions = [
{
assertion = config.security.polkit.enable;
message = "The libvirtd module currently requires Polkit to be enabled ('security.polkit.enable = true').";
}
{
assertion = builtins.elem "fd" cfg.qemu.ovmf.package.outputs;
message = "The option 'virtualisation.libvirtd.qemuOvmfPackage' needs a package that has an 'fd' output.";
}
];
environment = {
# this file is expected in /etc/qemu and not sysconfdir (/var/lib)
etc."qemu/bridge.conf".text = lib.concatMapStringsSep "\n"
(e:
"allow ${e}")
cfg.allowedBridges;
systemPackages = with pkgs; [ libressl.nc iptables cfg.package cfg.qemu.package ];
etc.ethertypes.source = "${pkgs.iptables}/etc/ethertypes";
};
boot.kernelModules = [ "tun" ];
users.groups.libvirtd.gid = config.ids.gids.libvirtd;
# libvirtd runs qemu as this user and group by default
users.extraGroups.qemu-libvirtd.gid = config.ids.gids.qemu-libvirtd;
users.extraUsers.qemu-libvirtd = {
uid = config.ids.uids.qemu-libvirtd;
isNormalUser = false;
group = "qemu-libvirtd";
};
security.wrappers.qemu-bridge-helper = {
setuid = true;
owner = "root";
group = "root";
source = "/run/${dirName}/nix-helpers/qemu-bridge-helper";
};
systemd.packages = [ cfg.package ];
systemd.services.libvirtd-config = {
description = "Libvirt Virtual Machine Management Daemon - configuration";
script = ''
# Copy default libvirt network config .xml files to /var/lib
# Files modified by the user will not be overwritten
for i in $(cd ${cfg.package}/var/lib && echo \
libvirt/qemu/networks/*.xml libvirt/qemu/networks/autostart/*.xml \
libvirt/nwfilter/*.xml );
do
mkdir -p /var/lib/$(dirname $i) -m 755
cp -npd ${cfg.package}/var/lib/$i /var/lib/$i
done
# Copy generated qemu config to libvirt directory
cp -f ${qemuConfigFile} /var/lib/${dirName}/qemu.conf
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# stable (not GC'able as in /nix/store) paths for using in <emulator> section of xml configs
for emulator in ${cfg.package}/libexec/libvirt_lxc ${cfg.qemu.package}/bin/qemu-kvm ${cfg.qemu.package}/bin/qemu-system-*; do
ln -s --force "$emulator" /run/${dirName}/nix-emulators/
done
for helper in libexec/qemu-bridge-helper bin/qemu-pr-helper; do
ln -s --force ${cfg.qemu.package}/$helper /run/${dirName}/nix-helpers/
done
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${optionalString cfg.qemu.ovmf.enable ''
ln -s --force ${cfg.qemu.ovmf.package.fd}/FV/${ovmfFilePrefix}_CODE.fd /run/${dirName}/nix-ovmf/
ln -s --force ${cfg.qemu.ovmf.package.fd}/FV/${ovmfFilePrefix}_VARS.fd /run/${dirName}/nix-ovmf/
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''}
'';
serviceConfig = {
Type = "oneshot";
RuntimeDirectoryPreserve = "yes";
LogsDirectory = subDirs [ "qemu" ];
RuntimeDirectory = subDirs [ "nix-emulators" "nix-helpers" "nix-ovmf" ];
StateDirectory = subDirs [ "dnsmasq" ];
};
};
systemd.services.libvirtd = {
requires = [ "libvirtd-config.service" ];
after = [ "libvirtd-config.service" ]
++ optional vswitch.enable "ovs-vswitchd.service";
environment.LIBVIRTD_ARGS = escapeShellArgs (
[
"--config"
configFile
"--timeout"
"120" # from ${libvirt}/var/lib/sysconfig/libvirtd
] ++ cfg.extraOptions
);
path = [ cfg.qemu.package ] # libvirtd requires qemu-img to manage disk images
++ optional vswitch.enable vswitch.package
++ optional cfg.qemu.swtpm.enable cfg.qemu.swtpm.package;
serviceConfig = {
Type = "notify";
KillMode = "process"; # when stopping, leave the VMs alone
Restart = "no";
};
restartIfChanged = false;
};
systemd.services.libvirt-guests = {
wantedBy = [ "multi-user.target" ];
path = with pkgs; [ coreutils gawk cfg.package ];
restartIfChanged = false;
environment.ON_BOOT = "${cfg.onBoot}";
environment.ON_SHUTDOWN = "${cfg.onShutdown}";
};
systemd.sockets.virtlogd = {
description = "Virtual machine log manager socket";
wantedBy = [ "sockets.target" ];
listenStreams = [ "/run/${dirName}/virtlogd-sock" ];
};
systemd.services.virtlogd = {
description = "Virtual machine log manager";
serviceConfig.ExecStart = "@${cfg.package}/sbin/virtlogd virtlogd";
restartIfChanged = false;
};
systemd.sockets.virtlockd = {
description = "Virtual machine lock manager socket";
wantedBy = [ "sockets.target" ];
listenStreams = [ "/run/${dirName}/virtlockd-sock" ];
};
systemd.services.virtlockd = {
description = "Virtual machine lock manager";
serviceConfig.ExecStart = "@${cfg.package}/sbin/virtlockd virtlockd";
restartIfChanged = false;
};
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# https://libvirt.org/daemons.html#monolithic-systemd-integration
systemd.sockets.libvirtd.wantedBy = [ "sockets.target" ];
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security.polkit.extraConfig = ''
polkit.addRule(function(action, subject) {
if (action.id == "org.libvirt.unix.manage" &&
subject.isInGroup("libvirtd")) {
return polkit.Result.YES;
}
});
'';
};
}