274 lines
		
	
	
		
			8.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			274 lines
		
	
	
		
			8.6 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, lib, pkgs, ... }:
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with lib;
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let
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  cfg = config.virtualisation.libvirtd;
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  vswitch = config.virtualisation.vswitch;
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  configFile = pkgs.writeText "libvirtd.conf" ''
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    unix_sock_group = "libvirtd"
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    unix_sock_rw_perms = "0770"
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    auth_unix_ro = "none"
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    auth_unix_rw = "none"
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    ${cfg.extraConfig}
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  '';
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  qemuConfigFile = pkgs.writeText "qemu.conf" ''
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    ${optionalString cfg.qemuOvmf ''
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      nvram = ["/run/libvirt/nix-ovmf/OVMF_CODE.fd:/run/libvirt/nix-ovmf/OVMF_VARS.fd"]
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    ''}
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    ${optionalString (!cfg.qemuRunAsRoot) ''
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      user = "qemu-libvirtd"
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      group = "qemu-libvirtd"
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    ''}
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    ${cfg.qemuVerbatimConfig}
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  '';
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  dirName = "libvirt";
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  subDirs = list: [ dirName ] ++ map (e: "${dirName}/${e}") list;
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in {
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  imports = [
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    (mkRemovedOptionModule [ "virtualisation" "libvirtd" "enableKVM" ]
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      "Set the option `virtualisation.libvirtd.qemuPackage' instead.")
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  ];
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  ###### interface
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  options.virtualisation.libvirtd = {
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    enable = mkOption {
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      type = types.bool;
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      default = false;
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      description = ''
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        This option enables libvirtd, a daemon that manages
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        virtual machines. Users in the "libvirtd" group can interact with
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        the daemon (e.g. to start or stop VMs) using the
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        <command>virsh</command> command line tool, among others.
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      '';
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    };
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    qemuPackage = mkOption {
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      type = types.package;
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      default = pkgs.qemu;
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      description = ''
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        Qemu package to use with libvirt.
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        `pkgs.qemu` can emulate alien architectures (e.g. aarch64 on x86)
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        `pkgs.qemu_kvm` saves disk space allowing to emulate only host architectures.
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      '';
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    };
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    extraConfig = mkOption {
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      type = types.lines;
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      default = "";
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      description = ''
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        Extra contents appended to the libvirtd configuration file,
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        libvirtd.conf.
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      '';
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    };
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    qemuRunAsRoot = mkOption {
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      type = types.bool;
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      default = true;
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      description = ''
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        If true,  libvirtd runs qemu as root.
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        If false, libvirtd runs qemu as unprivileged user qemu-libvirtd.
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        Changing this option to false may cause file permission issues
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        for existing guests. To fix these, manually change ownership
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        of affected files in /var/lib/libvirt/qemu to qemu-libvirtd.
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      '';
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    };
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    qemuVerbatimConfig = mkOption {
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      type = types.lines;
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      default = ''
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        namespaces = []
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      '';
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      description = ''
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        Contents written to the qemu configuration file, qemu.conf.
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        Make sure to include a proper namespace configuration when
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        supplying custom configuration.
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      '';
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    };
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    qemuOvmf = mkOption {
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      type = types.bool;
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      default = true;
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      description = ''
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        Allows libvirtd to take advantage of OVMF when creating new
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        QEMU VMs with UEFI boot.
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      '';
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    };
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    extraOptions = mkOption {
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      type = types.listOf types.str;
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      default = [ ];
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      example = [ "--verbose" ];
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      description = ''
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        Extra command line arguments passed to libvirtd on startup.
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      '';
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    };
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    onBoot = mkOption {
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      type = types.enum ["start" "ignore" ];
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      default = "start";
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      description = ''
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        Specifies the action to be done to / on the guests when the host boots.
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        The "start" option starts all guests that were running prior to shutdown
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        regardless of their autostart settings. The "ignore" option will not
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        start the formally running guest on boot. However, any guest marked as
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        autostart will still be automatically started by libvirtd.
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      '';
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    };
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    onShutdown = mkOption {
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      type = types.enum ["shutdown" "suspend" ];
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      default = "suspend";
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      description = ''
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        When shutting down / restarting the host what method should
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        be used to gracefully halt the guests. Setting to "shutdown"
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        will cause an ACPI shutdown of each guest. "suspend" will
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        attempt to save the state of the guests ready to restore on boot.
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      '';
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    };
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    allowedBridges = mkOption {
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      type = types.listOf types.str;
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      default = [ "virbr0" ];
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      description = ''
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        List of bridge devices that can be used by qemu:///session
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      '';
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    };
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  };
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  ###### implementation
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  config = mkIf cfg.enable {
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    environment = {
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      # this file is expected in /etc/qemu and not sysconfdir (/var/lib)
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      etc."qemu/bridge.conf".text = lib.concatMapStringsSep "\n" (e:
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        "allow ${e}") cfg.allowedBridges;
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      systemPackages = with pkgs; [ libvirt libressl.nc iptables cfg.qemuPackage ];
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      etc.ethertypes.source = "${pkgs.iptables}/etc/ethertypes";
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    };
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    boot.kernelModules = [ "tun" ];
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    users.groups.libvirtd.gid = config.ids.gids.libvirtd;
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    # libvirtd runs qemu as this user and group by default
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    users.extraGroups.qemu-libvirtd.gid = config.ids.gids.qemu-libvirtd;
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    users.extraUsers.qemu-libvirtd = {
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      uid = config.ids.uids.qemu-libvirtd;
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      isNormalUser = false;
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      group = "qemu-libvirtd";
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    };
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    security.wrappers.qemu-bridge-helper = {
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      source = "/run/${dirName}/nix-helpers/qemu-bridge-helper";
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    };
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    systemd.packages = [ pkgs.libvirt ];
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    systemd.services.libvirtd-config = {
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      description = "Libvirt Virtual Machine Management Daemon - configuration";
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      script = ''
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        # Copy default libvirt network config .xml files to /var/lib
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        # Files modified by the user will not be overwritten
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        for i in $(cd ${pkgs.libvirt}/var/lib && echo \
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            libvirt/qemu/networks/*.xml libvirt/qemu/networks/autostart/*.xml \
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            libvirt/nwfilter/*.xml );
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        do
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            mkdir -p /var/lib/$(dirname $i) -m 755
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            cp -npd ${pkgs.libvirt}/var/lib/$i /var/lib/$i
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        done
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        # Copy generated qemu config to libvirt directory
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        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
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        for emulator in ${pkgs.libvirt}/libexec/libvirt_lxc ${cfg.qemuPackage}/bin/qemu-kvm ${cfg.qemuPackage}/bin/qemu-system-*; do
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          ln -s --force "$emulator" /run/${dirName}/nix-emulators/
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        done
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        for helper in libexec/qemu-bridge-helper bin/qemu-pr-helper; do
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          ln -s --force ${cfg.qemuPackage}/$helper /run/${dirName}/nix-helpers/
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        done
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        ${optionalString cfg.qemuOvmf ''
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          ln -s --force ${pkgs.OVMF.fd}/FV/OVMF_CODE.fd /run/${dirName}/nix-ovmf/
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          ln -s --force ${pkgs.OVMF.fd}/FV/OVMF_VARS.fd /run/${dirName}/nix-ovmf/
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        ''}
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      '';
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      serviceConfig = {
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        Type = "oneshot";
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        RuntimeDirectoryPreserve = "yes";
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        LogsDirectory = subDirs [ "qemu" ];
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        RuntimeDirectory = subDirs [ "nix-emulators" "nix-helpers" "nix-ovmf" ];
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        StateDirectory = subDirs [ "dnsmasq" ];
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      };
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    };
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    systemd.services.libvirtd = {
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      requires = [ "libvirtd-config.service" ];
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      after = [ "systemd-udev-settle.service" "libvirtd-config.service" ]
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              ++ optional vswitch.enable "ovs-vswitchd.service";
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      environment.LIBVIRTD_ARGS = escapeShellArgs (
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        [ "--config" configFile
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          "--timeout" "120"     # from ${libvirt}/var/lib/sysconfig/libvirtd
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        ] ++ cfg.extraOptions);
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      path = [ cfg.qemuPackage ] # libvirtd requires qemu-img to manage disk images
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             ++ optional vswitch.enable vswitch.package;
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      serviceConfig = {
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        Type = "notify";
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        KillMode = "process"; # when stopping, leave the VMs alone
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        Restart = "no";
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      };
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      restartIfChanged = false;
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    };
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    systemd.services.libvirt-guests = {
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      wantedBy = [ "multi-user.target" ];
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      path = with pkgs; [ coreutils libvirt gawk ];
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      restartIfChanged = false;
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      environment.ON_BOOT = "${cfg.onBoot}";
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      environment.ON_SHUTDOWN = "${cfg.onShutdown}";
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    };
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    systemd.sockets.virtlogd = {
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      description = "Virtual machine log manager socket";
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      wantedBy = [ "sockets.target" ];
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      listenStreams = [ "/run/${dirName}/virtlogd-sock" ];
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    };
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    systemd.services.virtlogd = {
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      description = "Virtual machine log manager";
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      serviceConfig.ExecStart = "@${pkgs.libvirt}/sbin/virtlogd virtlogd";
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      restartIfChanged = false;
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    };
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    systemd.sockets.virtlockd = {
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      description = "Virtual machine lock manager socket";
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      wantedBy = [ "sockets.target" ];
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      listenStreams = [ "/run/${dirName}/virtlockd-sock" ];
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    };
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    systemd.services.virtlockd = {
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      description = "Virtual machine lock manager";
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      serviceConfig.ExecStart = "@${pkgs.libvirt}/sbin/virtlockd virtlockd";
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      restartIfChanged = false;
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    };
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    systemd.sockets.libvirtd    .wantedBy = [ "sockets.target" ];
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    systemd.sockets.libvirtd-tcp.wantedBy = [ "sockets.target" ];
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  };
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}
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