420 lines
13 KiB
Nix
420 lines
13 KiB
Nix
# This module creates a virtual machine from the NixOS configuration.
|
|
# Building the `config.system.build.vm' attribute gives you a command
|
|
# that starts a KVM/QEMU VM running the NixOS configuration defined in
|
|
# `config'. The Nix store is shared read-only with the host, which
|
|
# makes (re)building VMs very efficient. However, it also means you
|
|
# can't reconfigure the guest inside the guest - you need to rebuild
|
|
# the VM in the host. On the other hand, the root filesystem is a
|
|
# read/writable disk image persistent across VM reboots.
|
|
|
|
{ config, pkgs, ... }:
|
|
|
|
with pkgs.lib;
|
|
|
|
let
|
|
|
|
vmName =
|
|
if config.networking.hostName == ""
|
|
then "noname"
|
|
else config.networking.hostName;
|
|
|
|
options = {
|
|
|
|
virtualisation.memorySize =
|
|
mkOption {
|
|
default = 384;
|
|
description =
|
|
''
|
|
Memory size (M) of virtual machine.
|
|
'';
|
|
};
|
|
|
|
virtualisation.diskSize =
|
|
mkOption {
|
|
default = 512;
|
|
description =
|
|
''
|
|
Disk size (M) of virtual machine.
|
|
'';
|
|
};
|
|
|
|
virtualisation.diskImage =
|
|
mkOption {
|
|
default = "./${vmName}.qcow2";
|
|
description =
|
|
''
|
|
Path to the disk image containing the root filesystem.
|
|
The image will be created on startup if it does not
|
|
exist.
|
|
'';
|
|
};
|
|
|
|
virtualisation.graphics =
|
|
mkOption {
|
|
default = true;
|
|
description =
|
|
''
|
|
Whether to run QEMU with a graphics window, or access
|
|
the guest computer serial port through the host tty.
|
|
'';
|
|
};
|
|
|
|
virtualisation.pathsInNixDB =
|
|
mkOption {
|
|
default = [];
|
|
description =
|
|
''
|
|
The list of paths whose closure is registered in the Nix
|
|
database in the VM. All other paths in the host Nix store
|
|
appear in the guest Nix store as well, but are considered
|
|
garbage (because they are not registered in the Nix
|
|
database in the guest).
|
|
'';
|
|
};
|
|
|
|
virtualisation.vlans =
|
|
mkOption {
|
|
default = [ 1 ];
|
|
example = [ 1 2 ];
|
|
description =
|
|
''
|
|
Virtual networks to which the VM is connected. Each
|
|
number <replaceable>N</replaceable> in this list causes
|
|
the VM to have a virtual Ethernet interface attached to a
|
|
separate virtual network on which it will be assigned IP
|
|
address
|
|
<literal>192.168.<replaceable>N</replaceable>.<replaceable>M</replaceable></literal>,
|
|
where <replaceable>M</replaceable> is the index of this VM
|
|
in the list of VMs.
|
|
'';
|
|
};
|
|
|
|
virtualisation.writableStore =
|
|
mkOption {
|
|
default = false;
|
|
description =
|
|
''
|
|
If enabled, the Nix store in the VM is made writable by
|
|
layering a unionfs-fuse/tmpfs filesystem on top of the host's Nix
|
|
store.
|
|
'';
|
|
};
|
|
|
|
networking.primaryIPAddress =
|
|
mkOption {
|
|
default = "";
|
|
internal = true;
|
|
description = "Primary IP address used in /etc/hosts.";
|
|
};
|
|
|
|
virtualisation.qemu.options =
|
|
mkOption {
|
|
default = [];
|
|
example = [ "-vga std" ];
|
|
description = "Options passed to QEMU.";
|
|
};
|
|
|
|
virtualisation.useBootLoader =
|
|
mkOption {
|
|
default = false;
|
|
description =
|
|
''
|
|
If enabled, the virtual machine will be booted using the
|
|
regular boot loader (i.e., GRUB 1 or 2). This allows
|
|
testing of the boot loader. If
|
|
disabled (the default), the VM directly boots the NixOS
|
|
kernel and initial ramdisk, bypassing the boot loader
|
|
altogether.
|
|
'';
|
|
};
|
|
|
|
};
|
|
|
|
cfg = config.virtualisation;
|
|
|
|
qemuGraphics = if cfg.graphics then "" else "-nographic";
|
|
kernelConsole = if cfg.graphics then "" else "console=ttyS0";
|
|
ttys = [ "tty1" "tty2" "tty3" "tty4" "tty5" "tty6" ];
|
|
|
|
# Shell script to start the VM.
|
|
startVM =
|
|
''
|
|
#! ${pkgs.stdenv.shell}
|
|
|
|
NIX_DISK_IMAGE=$(readlink -f ''${NIX_DISK_IMAGE:-${config.virtualisation.diskImage}})
|
|
|
|
if ! test -e "$NIX_DISK_IMAGE"; then
|
|
${pkgs.qemu_kvm}/bin/qemu-img create -f qcow2 "$NIX_DISK_IMAGE" \
|
|
${toString config.virtualisation.diskSize}M || exit 1
|
|
fi
|
|
|
|
# Start Samba (which wants to put its socket and config files in TMPDIR).
|
|
if [ -z "$TMPDIR" -o -z "$USE_TMPDIR" ]; then
|
|
TMPDIR=$(mktemp -d nix-vm-smbd.XXXXXXXXXX --tmpdir)
|
|
fi
|
|
cd $TMPDIR
|
|
mkdir -p $TMPDIR/xchg
|
|
|
|
EXTRA_SAMBA_CONF="
|
|
[shared]
|
|
force user = $WHO
|
|
path = ''${SHARED_DIR:-$TMPDIR/xchg}
|
|
read only = no
|
|
guest ok = yes
|
|
"
|
|
|
|
${pkgs.vmTools.startSamba}
|
|
|
|
# Start QEMU.
|
|
# "-boot menu=on" is there, because I don't know how to make qemu boot from 2nd hd.
|
|
exec ${pkgs.qemu_kvm}/bin/qemu-kvm \
|
|
-name ${vmName} \
|
|
-m ${toString config.virtualisation.memorySize} \
|
|
${optionalString (pkgs.stdenv.system == "x86_64-linux") "-cpu kvm64"} \
|
|
-net nic,vlan=0,model=virtio \
|
|
-chardev socket,id=samba,path=./samba \
|
|
-net user,vlan=0,guestfwd=tcp:10.0.2.4:445-chardev:samba''${QEMU_NET_OPTS:+,$QEMU_NET_OPTS} \
|
|
${if cfg.useBootLoader then ''
|
|
-drive index=0,id=drive1,file=$NIX_DISK_IMAGE,if=virtio,cache=writeback,werror=report \
|
|
-drive index=1,id=drive2,file=${bootDisk}/disk.img,if=virtio,readonly \
|
|
-boot menu=on
|
|
'' else ''
|
|
-drive file=$NIX_DISK_IMAGE,if=virtio,cache=writeback,werror=report \
|
|
-kernel ${config.system.build.toplevel}/kernel \
|
|
-initrd ${config.system.build.toplevel}/initrd \
|
|
-append "$(cat ${config.system.build.toplevel}/kernel-params) init=${config.system.build.toplevel}/init regInfo=${regInfo} ${kernelConsole} $QEMU_KERNEL_PARAMS" \
|
|
''} \
|
|
${qemuGraphics} \
|
|
${toString config.virtualisation.qemu.options} \
|
|
$QEMU_OPTS
|
|
'';
|
|
|
|
|
|
regInfo = pkgs.runCommand "reginfo"
|
|
{ exportReferencesGraph =
|
|
map (x: [("closure-" + baseNameOf x) x]) config.virtualisation.pathsInNixDB;
|
|
buildInputs = [ pkgs.perl ];
|
|
preferLocalBuild = true;
|
|
}
|
|
''
|
|
printRegistration=1 perl ${pkgs.pathsFromGraph} closure-* > $out
|
|
'';
|
|
|
|
|
|
# Generate a hard disk image containing a /boot partition and GRUB
|
|
# in the MBR. Used when the `useBootLoader' option is set.
|
|
bootDisk =
|
|
pkgs.vmTools.runInLinuxVM (
|
|
pkgs.runCommand "nixos-boot-disk"
|
|
{ preVM =
|
|
''
|
|
mkdir $out
|
|
diskImage=$out/disk.img
|
|
${pkgs.vmTools.kvm}/bin/qemu-img create -f qcow2 $diskImage "32M"
|
|
'';
|
|
buildInputs = [ pkgs.utillinux ];
|
|
}
|
|
''
|
|
# Create a single /boot partition.
|
|
${pkgs.parted}/sbin/parted /dev/vda mklabel msdos
|
|
${pkgs.parted}/sbin/parted /dev/vda -- mkpart primary ext2 1M -1s
|
|
. /sys/class/block/vda1/uevent
|
|
mknod /dev/vda1 b $MAJOR $MINOR
|
|
. /sys/class/block/vda/uevent
|
|
${pkgs.e2fsprogs}/sbin/mkfs.ext4 -L boot /dev/vda1
|
|
${pkgs.e2fsprogs}/sbin/tune2fs -c 0 -i 0 /dev/vda1
|
|
|
|
# Mount /boot.
|
|
mkdir /boot
|
|
mount /dev/vda1 /boot
|
|
|
|
# This is needed for GRUB 0.97, which doesn't know about virtio devices.
|
|
mkdir /boot/grub
|
|
echo '(hd0) /dev/vda' > /boot/grub/device.map
|
|
|
|
# Install GRUB and generate the GRUB boot menu.
|
|
touch /etc/NIXOS
|
|
mkdir -p /nix/var/nix/profiles
|
|
${config.system.build.toplevel}/bin/switch-to-configuration boot
|
|
|
|
umount /boot
|
|
''
|
|
);
|
|
|
|
in
|
|
|
|
{
|
|
require = [ options ../profiles/qemu-guest.nix ];
|
|
|
|
boot.loader.grub.device = mkOverride 50 "/dev/vda";
|
|
|
|
# All the modules the initrd needs to mount the host filesystem via
|
|
# CIFS. Also use paravirtualised network and block devices for
|
|
# performance.
|
|
boot.initrd.availableKernelModules =
|
|
[ "cifs" "nls_utf8" "hmac" "md4" "ecb" "des_generic" ];
|
|
|
|
boot.initrd.supportedFilesystems = optional cfg.writableStore "unionfs-fuse";
|
|
|
|
boot.initrd.extraUtilsCommands =
|
|
''
|
|
# We need mke2fs in the initrd.
|
|
cp ${pkgs.e2fsprogs}/sbin/mke2fs $out/bin
|
|
'';
|
|
|
|
boot.initrd.postDeviceCommands =
|
|
''
|
|
# Set up networking. Needed for CIFS mounting.
|
|
ip link set eth0 up
|
|
ip addr add 10.0.2.15/24 dev eth0
|
|
|
|
# If the disk image appears to be empty, run mke2fs to
|
|
# initialise.
|
|
FSTYPE=$(blkid -o value -s TYPE /dev/vda || true)
|
|
if test -z "$FSTYPE"; then
|
|
mke2fs -t ext4 /dev/vda
|
|
fi
|
|
'';
|
|
|
|
boot.initrd.postMountCommands =
|
|
''
|
|
# Mark this as a NixOS machinex.
|
|
mkdir -p $targetRoot/etc
|
|
echo -n > $targetRoot/etc/NIXOS
|
|
|
|
# Fix the permissions on /tmp.
|
|
chmod 1777 $targetRoot/tmp
|
|
|
|
mkdir -p $targetRoot/boot
|
|
mount -o remount,ro $targetRoot/nix/store
|
|
${optionalString cfg.writableStore ''
|
|
mkdir -p /unionfs-chroot/ro-store
|
|
mount --rbind $targetRoot/nix/store /unionfs-chroot/ro-store
|
|
|
|
mkdir /unionfs-chroot/rw-store
|
|
mount -t tmpfs -o "mode=755" none /unionfs-chroot/rw-store
|
|
unionfs -o allow_other,cow,nonempty,chroot=/unionfs-chroot,max_files=32768 /rw-store=RW:/ro-store=RO $targetRoot/nix/store
|
|
''}
|
|
'';
|
|
|
|
# After booting, register the closure of the paths in
|
|
# `virtualisation.pathsInNixDB' in the Nix database in the VM. This
|
|
# allows Nix operations to work in the VM. The path to the
|
|
# registration file is passed through the kernel command line to
|
|
# allow `system.build.toplevel' to be included. (If we had a direct
|
|
# reference to ${regInfo} here, then we would get a cyclic
|
|
# dependency.)
|
|
boot.postBootCommands =
|
|
''
|
|
( source /proc/cmdline
|
|
if [ -n "$regInfo" ]; then
|
|
${config.environment.nix}/bin/nix-store --load-db < $regInfo
|
|
fi
|
|
)
|
|
'';
|
|
|
|
virtualisation.pathsInNixDB = [ config.system.build.toplevel ];
|
|
|
|
virtualisation.qemu.options = [ "-vga std" "-usbdevice tablet" ];
|
|
|
|
# Mount the host filesystem via CIFS, and bind-mount the Nix store
|
|
# of the host into our own filesystem. We use mkOverride to allow
|
|
# this module to be applied to "normal" NixOS system configuration,
|
|
# where the regular value for the `fileSystems' attribute should be
|
|
# disregarded for the purpose of building a VM test image (since
|
|
# those filesystems don't exist in the VM).
|
|
fileSystems =
|
|
{ "/".device = "/dev/vda";
|
|
"/nix/store" =
|
|
{ device = "//10.0.2.4/store";
|
|
fsType = "cifs";
|
|
options = "guest,sec=none,noperm,noacl";
|
|
};
|
|
"/tmp/xchg" =
|
|
{ device = "//10.0.2.4/xchg";
|
|
fsType = "cifs";
|
|
options = "guest,sec=none,noperm,noacl";
|
|
neededForBoot = true;
|
|
};
|
|
"/tmp/shared" =
|
|
{ device = "//10.0.2.4/shared";
|
|
fsType = "cifs";
|
|
options = "guest,sec=none,noperm,noacl";
|
|
neededForBoot = true;
|
|
};
|
|
} // optionalAttrs cfg.useBootLoader
|
|
{ "/boot" =
|
|
{ device = "/dev/disk/by-label/boot";
|
|
fsType = "ext4";
|
|
options = "ro";
|
|
noCheck = true; # fsck fails on a r/o filesystem
|
|
};
|
|
};
|
|
|
|
swapDevices = mkOverride 50 [ ];
|
|
|
|
# Starting DHCP brings down eth0, which kills the connection to the
|
|
# host filesystem and thus deadlocks the system.
|
|
networking.useDHCP = false;
|
|
|
|
networking.defaultGateway = mkOverride 200 "10.0.2.2";
|
|
|
|
networking.nameservers = [ "10.0.2.3" ];
|
|
|
|
networking.interfaces = singleton
|
|
{ name = "eth0";
|
|
ipAddress = "10.0.2.15";
|
|
prefixLength = 24;
|
|
};
|
|
|
|
# Don't run ntpd in the guest. It should get the correct time from KVM.
|
|
services.ntp.enable = false;
|
|
|
|
system.build.vm = pkgs.runCommand "nixos-vm" { preferLocalBuild = true; }
|
|
''
|
|
ensureDir $out/bin
|
|
ln -s ${config.system.build.toplevel} $out/system
|
|
ln -s ${pkgs.writeScript "run-nixos-vm" startVM} $out/bin/run-${vmName}-vm
|
|
'';
|
|
|
|
# sendfile() is currently broken over CIFS, so fix it here for all
|
|
# configurations that use Apache.
|
|
services.httpd.extraConfig =
|
|
''
|
|
EnableSendFile Off
|
|
'';
|
|
|
|
# When building a regular system configuration, override whatever
|
|
# video driver the host uses.
|
|
services.xserver.videoDriver = mkOverride 50 null;
|
|
services.xserver.videoDrivers = mkOverride 50 [ "vesa" ];
|
|
services.xserver.defaultDepth = mkOverride 50 0;
|
|
services.xserver.resolutions = mkOverride 50 [ { x = 1024; y = 768; } ];
|
|
services.xserver.monitorSection =
|
|
''
|
|
# Set a higher refresh rate so that resolutions > 800x600 work.
|
|
HorizSync 30-140
|
|
VertRefresh 50-160
|
|
'';
|
|
|
|
# Wireless won't work in the VM.
|
|
networking.wireless.enable = mkOverride 50 false;
|
|
|
|
system.requiredKernelConfig = with config.lib.kernelConfig;
|
|
[ (isEnabled "VIRTIO_BLK")
|
|
(isEnabled "VIRTIO_PCI")
|
|
(isEnabled "VIRTIO_NET")
|
|
(isEnabled "EXT4_FS")
|
|
(isEnabled "CIFS")
|
|
(isYes "BLK_DEV")
|
|
(isYes "PCI")
|
|
(isYes "EXPERIMENTAL")
|
|
(isYes "NETDEVICES")
|
|
(isYes "NET_CORE")
|
|
(isYes "INET")
|
|
(isYes "NETWORK_FILESYSTEMS")
|
|
] ++ optional (!cfg.graphics) [
|
|
(isYes "SERIAL_8250_CONSOLE")
|
|
(isYes "SERIAL_8250")
|
|
];
|
|
}
|