166 lines
5 KiB
Nix
166 lines
5 KiB
Nix
# Systemd services for libvirtd.
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{ config, pkgs, ... }:
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with pkgs.lib;
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let
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cfg = config.virtualisation.libvirtd;
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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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in
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{
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###### interface
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options = {
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virtualisation.libvirtd.enable =
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mkOption {
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type = types.bool;
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default = false;
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description =
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''
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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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virtualisation.libvirtd.enableKVM =
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mkOption {
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type = types.bool;
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default = true;
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description =
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''
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This option enables support for QEMU/KVM in libvirtd.
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'';
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};
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virtualisation.libvirtd.extraConfig =
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mkOption {
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type = types.lines;
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default = "";
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description =
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''
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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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};
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###### implementation
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config = mkIf cfg.enable {
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environment.systemPackages =
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[ pkgs.libvirt pkgs.netcat-openbsd ]
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++ optional cfg.enableKVM pkgs.qemu_kvm;
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boot.kernelModules = [ "tun" ];
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systemd.services.libvirtd =
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{ description = "Libvirt Virtual Machine Management Daemon";
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wantedBy = [ "multi-user.target" ];
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after = [ "systemd-udev-settle.service" ];
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path =
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[ pkgs.bridge_utils pkgs.dmidecode pkgs.dnsmasq
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pkgs.ebtables
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] ++ optional cfg.enableKVM pkgs.qemu_kvm;
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preStart =
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''
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mkdir -p /var/log/libvirt/qemu -m 755
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rm -f /var/run/libvirtd.pid
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mkdir -p /var/lib/libvirt
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mkdir -p /var/lib/libvirt/dnsmasq
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chmod 755 /var/lib/libvirt
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chmod 755 /var/lib/libvirt/dnsmasq
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# Libvirt unfortunately writes mutable state (such as
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# runtime changes to VM, network or filter configurations)
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# to /etc. So we can't use environment.etc to make the
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# default network and filter definitions available, since
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# libvirt will then modify the originals in the Nix store.
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# So here we copy them instead. Ugly.
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for i in $(cd ${pkgs.libvirt}/etc && echo \
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libvirt/qemu/networks/*.xml libvirt/qemu/networks/autostart/*.xml \
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libvirt/nwfilter/*.xml );
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do
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mkdir -p /etc/$(dirname $i) -m 755
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cp -fpd ${pkgs.libvirt}/etc/$i /etc/$i
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done
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# libvirtd puts the full path of the emulator binary in the machine
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# config file. But this path can unfortunately be garbage collected
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# while still being used by the virtual machine. So update the
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# emulator path on each startup to something valid (re-scan $PATH).
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for file in /etc/libvirt/qemu/*.xml; do
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test -f "$file" || continue
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# get (old) emulator path from config file
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emulator=$(grep "^[[:space:]]*<emulator>" "$file" | sed 's,^[[:space:]]*<emulator>\(.*\)</emulator>.*,\1,')
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# get a (definitely) working emulator path by re-scanning $PATH
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new_emulator=$(command -v $(basename "$emulator"))
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# write back
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sed -i "s,^[[:space:]]*<emulator>.*, <emulator>$new_emulator</emulator> <!-- WARNING: emulator dirname is auto-updated by the nixos libvirtd module -->," "$file"
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done
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''; # */
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serviceConfig.ExecStart = ''@${pkgs.libvirt}/sbin/libvirtd libvirtd --config "${configFile}" --daemon --verbose'';
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serviceConfig.Type = "forking";
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serviceConfig.KillMode = "process"; # when stopping, leave the VMs alone
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# Wait until libvirtd is ready to accept requests.
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postStart =
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''
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for ((i = 0; i < 60; i++)); do
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if ${pkgs.libvirt}/bin/virsh list > /dev/null; then exit 0; fi
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sleep 1
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done
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exit 1 # !!! seems to be ignored
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'';
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};
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jobs."libvirt-guests" =
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{ description = "Libvirt Virtual Machines";
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wantedBy = [ "multi-user.target" ];
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wants = [ "libvirtd.service" ];
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after = [ "libvirtd.service" ];
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restartIfChanged = false;
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path = [ pkgs.gettext pkgs.libvirt pkgs.gawk ];
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preStart =
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''
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mkdir -p /var/lock/subsys -m 755
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${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests start || true
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'';
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postStop = "${pkgs.libvirt}/etc/rc.d/init.d/libvirt-guests stop";
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serviceConfig.Type = "oneshot";
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serviceConfig.RemainAfterExit = true;
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};
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users.extraGroups.libvirtd.gid = config.ids.gids.libvirtd;
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};
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}
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