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# This module creates a bootable ISO image containing the given NixOS
# configuration. The derivation for the ISO image will be placed in
# config.system.build.isoImage.
{config, pkgs, ...}:
let
options = {
isoImage.isoName = pkgs.lib.mkOption {
default = "cd.iso";
description = ''
Name of the generated ISO image file.
'';
};
isoImage.compressImage = pkgs.lib.mkOption {
default = false;
description = ''
Whether the ISO image should be compressed using
<command>bzip2</command>.
'';
};
isoImage.volumeID = pkgs.lib.mkOption {
default = "NIXOS_BOOT_CD";
description = ''
Specifies the label or volume ID of the generated ISO image.
Note that the label is used by stage 1 of the boot process to
mount the CD, so it should be reasonably distinctive.
'';
};
isoImage.contents = pkgs.lib.mkOption {
example =
[ { source = pkgs.memtest86 + "/memtest.bin";
target = "boot/memtest.bin";
}
];
description = ''
This option lists files to be copied to fixed locations in the
generated ISO image.
'';
};
isoImage.storeContents = pkgs.lib.mkOption {
example = [pkgs.stdenv];
description = ''
This option lists additional derivations to be included in the
Nix store in the generated ISO image.
'';
};
};
# The configuration file for Grub.
grubCfg =
''
default 0
timeout 10
splashimage /boot/background.xpm.gz
${config.boot.extraGrubEntries}
'';
in
{
require = options;
# In stage 1 of the boot, mount the CD/DVD as the root FS by label
# so that we don't need to know its device.
fileSystems =
[ { mountPoint = "/";
label = config.isoImage.volumeID;
}
{ mountPoint = "/nix/store";
fsType = "squashfs";
device = "/nix-store.squashfs";
options = "loop";
neededForBoot = true;
}
];
# We need squashfs in the initrd to mount the compressed Nix store,
# and aufs to make the root filesystem appear writable.
boot.extraModulePackages = [config.boot.kernelPackages.aufs];
boot.initrd.extraKernelModules = ["aufs" "squashfs"];
# Tell stage 1 of the boot to mount a tmpfs on top of the CD using
# AUFS. !!! It would be nicer to make the stage 1 init pluggable
# and move that bit of code here.
boot.isLiveCD = true;
# Closures to be copied to the Nix store on the CD, namely the init
# script and the top-level system configuration directory.
isoImage.storeContents =
[ config.system.build.bootStage2
config.system.build.system
];
# Create the squashfs image that contains the Nix store.
system.build.squashfsStore = import ../../../lib/make-squashfs.nix {
inherit (pkgs) stdenv squashfsTools perl pathsFromGraph;
storeContents = config.isoImage.storeContents;
};
# Individual files to be included on the CD, outside of the Nix
# store on the CD.
isoImage.contents =
[ { source = "${pkgs.grub}/lib/grub/${if pkgs.stdenv.system == "i686-linux" then "i386-pc" else "x86_64-unknown"}/stage2_eltorito";
target = "/boot/grub/stage2_eltorito";
}
{ source = pkgs.writeText "menu.lst" grubCfg;
target = "/boot/grub/menu.lst";
}
{ source = config.boot.kernelPackages.kernel + "/vmlinuz";
target = "/boot/vmlinuz";
}
{ source = config.system.build.initialRamdisk + "/initrd";
target = "/boot/initrd";
}
{ source = config.boot.grubSplashImage;
target = "/boot/background.xpm.gz";
}
{ source = config.system.build.squashfsStore;
target = "/nix-store.squashfs";
}
{ # Quick hack: need a mount point for the store.
source = pkgs.runCommand "empty" {} "ensureDir $out";
target = "/nix/store";
}
{ # Another quick hack: the kernel needs a systemConfig
# parameter in menu.lst, but the system config depends on
# menu.lst. Break the cyclic dependency by having a /system
# symlink on the CD, and having menu.lst refer to /system.
source = pkgs.runCommand "system" {}
"ln -s ${config.system.build.system} $out";
target = "/system";
}
{ # Idem for the stage-2 init script.
source = pkgs.runCommand "system" {}
"ln -s ${config.system.build.bootStage2} $out";
target = "/init";
}
];
# The Grub menu.
boot.extraGrubEntries =
''
title Boot from hard disk
root (hd0)
chainloader +1
title NixOS Installer / Rescue
kernel /boot/vmlinuz init=/init systemConfig=/system ${toString config.boot.kernelParams}
initrd /boot/initrd
'';
# Create the ISO image.
system.build.isoImage = import ../../../lib/make-iso9660-image.nix {
inherit (pkgs) stdenv perl cdrkit pathsFromGraph;
inherit (config.isoImage) isoName compressImage volumeID contents;
bootable = true;
bootImage = "/boot/grub/stage2_eltorito";
};
boot.postBootCommands =
''
# After booting, register the contents of the Nix store on the
# CD in the Nix database in the tmpfs.
${config.environment.nix}/bin/nix-store --load-db < /nix/store/nix-path-registration
# nixos-rebuild also requires a "system" profile and an
# /etc/NIXOS tag.
touch /etc/NIXOS
${config.environment.nix}/bin/nix-env -p /nix/var/nix/profiles/system --set /var/run/current-system
'';
}