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|
# This module creates netboot media containing the given NixOS
# configuration.
{
config,
lib,
pkgs,
modulesPath,
...
}:
with lib;
{
imports = [
../../image/file-options.nix
];
options = {
netboot.squashfsCompression = mkOption {
default = "zstd -Xcompression-level 19";
description = ''
Compression settings to use for the squashfs nix store.
'';
example = "zstd -Xcompression-level 6";
type = types.str;
};
netboot.storeContents = mkOption {
example = literalExpression "[ pkgs.stdenv ]";
description = ''
This option lists additional derivations to be included in the
Nix store in the generated netboot image.
'';
};
};
config = {
# Don't build the GRUB menu builder script, since we don't need it
# here and it causes a cyclic dependency.
boot.loader.grub.enable = false;
fileSystems."/" = mkImageMediaOverride {
fsType = "tmpfs";
options = [ "mode=0755" ];
};
# In stage 1, mount a tmpfs on top of /nix/store (the squashfs
# image) to make this a live CD.
fileSystems."/nix/.ro-store" = mkImageMediaOverride {
fsType = "squashfs";
device = "../nix-store.squashfs";
options = [
"loop"
]
++ lib.optional (config.boot.kernelPackages.kernel.kernelAtLeast "6.2") "threads=multi";
neededForBoot = true;
};
fileSystems."/nix/.rw-store" = mkImageMediaOverride {
fsType = "tmpfs";
options = [ "mode=0755" ];
neededForBoot = true;
};
fileSystems."/nix/store" = mkImageMediaOverride {
overlay = {
lowerdir = [ "/nix/.ro-store" ];
upperdir = "/nix/.rw-store/store";
workdir = "/nix/.rw-store/work";
};
neededForBoot = true;
};
boot.initrd.availableKernelModules = [
"squashfs"
"overlay"
];
boot.initrd.kernelModules = [
"loop"
"overlay"
];
# Closures to be copied to the Nix store, namely the init
# script and the top-level system configuration directory.
netboot.storeContents = [ config.system.build.toplevel ];
# Create the squashfs image that contains the Nix store.
system.build.squashfsStore = pkgs.callPackage ../../../lib/make-squashfs.nix {
storeContents = config.netboot.storeContents;
comp = config.netboot.squashfsCompression;
};
# Create the initrd
system.build.netbootRamdisk = pkgs.makeInitrdNG {
inherit (config.boot.initrd) compressor compressorArgs;
prepend = [ "${config.system.build.initialRamdisk}/initrd" ];
contents = [
{
source = config.system.build.squashfsStore;
target = "/nix-store.squashfs";
}
];
};
system.build.netbootIpxeScript = pkgs.writeTextDir "netboot.ipxe" ''
#!ipxe
# Use the cmdline variable to allow the user to specify custom kernel params
# when chainloading this script from other iPXE scripts like netboot.xyz
kernel ${config.boot.kernelPackages.kernel.target} init=${config.system.build.toplevel}/init initrd=initrd ${toString config.boot.kernelParams} ''${cmdline}
initrd initrd
boot
'';
# A script invoking kexec on ./bzImage and ./initrd.gz.
# Usually used through system.build.kexecTree, but exposed here for composability.
system.build.kexecScript = pkgs.writeScript "kexec-boot" ''
#!/usr/bin/env bash
if ! kexec -v >/dev/null 2>&1; then
echo "kexec not found: please install kexec-tools" 2>&1
exit 1
fi
SCRIPT_DIR=$( cd -- "$( dirname -- "''${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
kexec --load ''${SCRIPT_DIR}/bzImage \
--initrd=''${SCRIPT_DIR}/initrd.gz \
--command-line "init=${config.system.build.toplevel}/init ${toString config.boot.kernelParams}"
kexec -e
'';
# A tree containing initrd.gz, bzImage and a kexec-boot script.
system.build.kexecTree = pkgs.linkFarm "kexec-tree" [
{
name = "initrd.gz";
path = "${config.system.build.netbootRamdisk}/initrd";
}
{
name = "bzImage";
path = "${config.system.build.kernel}/${config.system.boot.loader.kernelFile}";
}
{
name = "kexec-boot";
path = config.system.build.kexecScript;
}
];
image.extension = "tar.xz";
image.filePath = "tarball/${config.image.fileName}";
system.nixos.tags = [ "kexec" ];
system.build.image = config.system.build.kexecTarball;
system.build.kexecTarball =
pkgs.callPackage "${toString modulesPath}/../lib/make-system-tarball.nix"
{
fileName = config.image.baseName;
storeContents = [
{
object = config.system.build.kexecScript;
symlink = "/kexec_nixos";
}
];
contents = [ ];
};
boot.loader.timeout = 10;
systemd.services.register-nix-paths = {
description = "Register Nix Store Paths";
unitConfig.DefaultDependencies = false;
wantedBy = [ "sysinit.target" ];
before = [
"sysinit.target"
"shutdown.target"
"nix-daemon.socket"
"nix-daemon.service"
];
after = [ "local-fs.target" ];
conflicts = [ "shutdown.target" ];
restartIfChanged = false;
serviceConfig = {
Type = "oneshot";
RemainAfterExit = true;
};
script = ''
# After booting, register the contents of the Nix store
# in the Nix database in the tmpfs.
${lib.getExe' config.nix.package "nix-store"} --load-db < /nix/store/nix-path-registration
# nixos-rebuild also requires a "system" profile and an /etc/NIXOS tag.
touch /etc/NIXOS
${lib.getExe' config.nix.package "nix-env"} -p /nix/var/nix/profiles/system --set /run/current-system
'';
};
boot.postBootCommands = ''
# Set password for user nixos if specified on cmdline
# Allows using nixos-anywhere in headless environments
for o in $(</proc/cmdline); do
case "$o" in
live.nixos.passwordHash=*)
set -- $(IFS==; echo $o)
${lib.getExe pkgs.gnugrep} -q "root::" /etc/shadow && ${lib.getExe' pkgs.shadow "usermod"} -p "$2" root
;;
live.nixos.password=*)
set -- $(IFS==; echo $o)
${lib.getExe pkgs.gnugrep} -q "root::" /etc/shadow && echo "root:$2" | ${lib.getExe' pkgs.shadow "chpasswd"}
;;
esac
done
'';
};
}
|
