nixpkgs/nixos/lib/make-disk-image.nix

156 lines
4.9 KiB
Nix

{ pkgs
, lib
, # The NixOS configuration to be installed onto the disk image.
config
, # The size of the disk, in megabytes.
diskSize
# The files and directories to be placed in the target file system.
# This is a list of attribute sets {source, target} where `source'
# is the file system object (regular file or directory) to be
# grafted in the file system at path `target'.
, contents ? []
, # Whether the disk should be partitioned (with a single partition
# containing the root filesystem) or contain the root filesystem
# directly.
partitioned ? true
# Whether to invoke switch-to-configuration boot during image creation
, installBootLoader ? true
, # The root file system type.
fsType ? "ext4"
, # The initial NixOS configuration file to be copied to
# /etc/nixos/configuration.nix.
configFile ? null
, # Shell code executed after the VM has finished.
postVM ? ""
, name ? "nixos-disk-image"
# This prevents errors while checking nix-store validity, see
# https://github.com/NixOS/nix/issues/1134
, fixValidity ? true
, format ? "raw"
}:
with lib;
pkgs.vmTools.runInLinuxVM (
pkgs.runCommand name
{ preVM =
''
mkdir $out
diskImage=$out/nixos.${if format == "qcow2" then "qcow2" else "img"}
${pkgs.vmTools.qemu}/bin/qemu-img create -f ${format} $diskImage "${toString diskSize}M"
mv closure xchg/
'';
buildInputs = with pkgs; [ utillinux perl e2fsprogs parted rsync ];
# I'm preserving the line below because I'm going to search for it across nixpkgs to consolidate
# image building logic. The comment right below this now appears in 4 different places in nixpkgs :)
# !!! should use XML.
sources = map (x: x.source) contents;
targets = map (x: x.target) contents;
exportReferencesGraph =
[ "closure" config.system.build.toplevel ];
inherit postVM;
memSize = 1024;
}
''
${if partitioned then ''
# Create a single / partition.
parted /dev/vda mklabel msdos
parted /dev/vda -- mkpart primary ext2 1M -1s
. /sys/class/block/vda1/uevent
mknod /dev/vda1 b $MAJOR $MINOR
rootDisk=/dev/vda1
'' else ''
rootDisk=/dev/vda
''}
# Create an empty filesystem and mount it.
mkfs.${fsType} -L nixos $rootDisk
mkdir /mnt
mount $rootDisk /mnt
# Register the paths in the Nix database.
printRegistration=1 perl ${pkgs.pathsFromGraph} /tmp/xchg/closure | \
${config.nix.package.out}/bin/nix-store --load-db --option build-users-group ""
${if fixValidity then ''
# Add missing size/hash fields to the database. FIXME:
# exportReferencesGraph should provide these directly.
${config.nix.package.out}/bin/nix-store --verify --check-contents --option build-users-group ""
'' else ""}
# In case the bootloader tries to write to /dev/sda
ln -s vda /dev/xvda
ln -s vda /dev/sda
# Install the closure onto the image
USER=root ${config.system.build.nixos-install}/bin/nixos-install \
--closure ${config.system.build.toplevel} \
--no-channel-copy \
--no-root-passwd \
${optionalString (!installBootLoader) "--no-bootloader"}
# Install a configuration.nix.
mkdir -p /mnt/etc/nixos
${optionalString (configFile != null) ''
cp ${configFile} /mnt/etc/nixos/configuration.nix
''}
# Remove /etc/machine-id so that each machine cloning this image will get its own id
rm -f /mnt/etc/machine-id
# Copy arbitrary other files into the image
# Semi-shamelessly copied from make-etc.sh. I (@copumpkin) shall factor this stuff out as part of
# https://github.com/NixOS/nixpkgs/issues/23052.
set -f
sources_=($sources)
targets_=($targets)
set +f
for ((i = 0; i < ''${#targets_[@]}; i++)); do
source="''${sources_[$i]}"
target="''${targets_[$i]}"
if [[ "$source" =~ '*' ]]; then
# If the source name contains '*', perform globbing.
mkdir -p /mnt/$target
for fn in $source; do
rsync -a --no-o --no-g "$fn" /mnt/$target/
done
else
mkdir -p /mnt/$(dirname $target)
if ! [ -e /mnt/$target ]; then
rsync -a --no-o --no-g $source /mnt/$target
else
echo "duplicate entry $target -> $source"
exit 1
fi
fi
done
umount /mnt
# Make sure resize2fs works. Note that resize2fs has stricter criteria for resizing than a normal
# mount, so the `-c 0` and `-i 0` don't affect it. Setting it to `now` doesn't produce deterministic
# output, of course, but we can fix that when/if we start making images deterministic.
${optionalString (fsType == "ext4") ''
tune2fs -T now -c 0 -i 0 $rootDisk
''}
''
)