diff options
Diffstat (limited to 'nixpkgs/nixos/lib/make-disk-image.nix')
| -rw-r--r-- | nixpkgs/nixos/lib/make-disk-image.nix | 247 |
1 files changed, 247 insertions, 0 deletions
diff --git a/nixpkgs/nixos/lib/make-disk-image.nix b/nixpkgs/nixos/lib/make-disk-image.nix new file mode 100644 index 00000000000..5e86ea479d5 --- /dev/null +++ b/nixpkgs/nixos/lib/make-disk-image.nix @@ -0,0 +1,247 @@ +{ 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 ? [] + +, # Type of partition table to use; either "legacy", "efi", or "none". + # For "efi" images, the GPT partition table is used and a mandatory ESP + # partition of reasonable size is created in addition to the root partition. + # If `installBootLoader` is true, GRUB will be installed in EFI mode. + # For "legacy", the msdos partition table is used and a single large root + # partition is created. If `installBootLoader` is true, GRUB will be + # installed in legacy mode. + # For "none", no partition table is created. Enabling `installBootLoader` + # most likely fails as GRUB will probably refuse to install. + partitionTableType ? "legacy" + +, # The root file system type. + fsType ? "ext4" + +, # Filesystem label + label ? "nixos" + +, # 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" + +, # Disk image format, one of qcow2, qcow2-compressed, vpc, raw. + format ? "raw" +}: + +assert partitionTableType == "legacy" || partitionTableType == "efi" || partitionTableType == "none"; +# We use -E offset=X below, which is only supported by e2fsprogs +assert partitionTableType != "none" -> fsType == "ext4"; + +with lib; + +let format' = format; in let + + format = if format' == "qcow2-compressed" then "qcow2" else format'; + + compress = optionalString (format' == "qcow2-compressed") "-c"; + + filename = "nixos." + { + qcow2 = "qcow2"; + vpc = "vhd"; + raw = "img"; + }.${format}; + + rootPartition = { # switch-case + legacy = "1"; + efi = "2"; + }.${partitionTableType}; + + partitionDiskScript = { # switch-case + legacy = '' + parted --script $diskImage -- \ + mklabel msdos \ + mkpart primary ext4 1MiB -1 + ''; + efi = '' + parted --script $diskImage -- \ + mklabel gpt \ + mkpart ESP fat32 8MiB 256MiB \ + set 1 boot on \ + mkpart primary ext4 256MiB -1 + ''; + none = ""; + }.${partitionTableType}; + + nixpkgs = cleanSource pkgs.path; + + # FIXME: merge with channel.nix / make-channel.nix. + channelSources = pkgs.runCommand "nixos-${config.system.nixos.version}" {} '' + mkdir -p $out + cp -prd ${nixpkgs.outPath} $out/nixos + chmod -R u+w $out/nixos + if [ ! -e $out/nixos/nixpkgs ]; then + ln -s . $out/nixos/nixpkgs + fi + rm -rf $out/nixos/.git + echo -n ${config.system.nixos.versionSuffix} > $out/nixos/.version-suffix + ''; + + binPath = with pkgs; makeBinPath ( + [ rsync + utillinux + parted + e2fsprogs + lkl + config.system.build.nixos-install + config.system.build.nixos-enter + nix + ] ++ stdenv.initialPath); + + # I'm preserving the line below because I'm going to search for it across nixpkgs to consolidate + # image building logic. The comment right below this now appears in 4 different places in nixpkgs :) + # !!! should use XML. + sources = map (x: x.source) contents; + targets = map (x: x.target) contents; + + closureInfo = pkgs.closureInfo { rootPaths = [ config.system.build.toplevel channelSources ]; }; + + prepareImage = '' + export PATH=${binPath} + + # Yes, mkfs.ext4 takes different units in different contexts. Fun. + sectorsToKilobytes() { + echo $(( ( "$1" * 512 ) / 1024 )) + } + + sectorsToBytes() { + echo $(( "$1" * 512 )) + } + + mkdir $out + diskImage=nixos.raw + truncate -s ${toString diskSize}M $diskImage + + ${partitionDiskScript} + + ${if partitionTableType != "none" then '' + # Get start & length of the root partition in sectors to $START and $SECTORS. + eval $(partx $diskImage -o START,SECTORS --nr ${rootPartition} --pairs) + + mkfs.${fsType} -F -L ${label} $diskImage -E offset=$(sectorsToBytes $START) $(sectorsToKilobytes $SECTORS)K + '' else '' + mkfs.${fsType} -F -L ${label} $diskImage + ''} + + root="$PWD/root" + mkdir -p $root + + # Copy arbitrary other files into the image + # Semi-shamelessly copied from make-etc.sh. I (@copumpkin) shall factor this stuff out as part of + # https://github.com/NixOS/nixpkgs/issues/23052. + set -f + sources_=(${concatStringsSep " " sources}) + targets_=(${concatStringsSep " " targets}) + set +f + + for ((i = 0; i < ''${#targets_[@]}; i++)); do + source="''${sources_[$i]}" + target="''${targets_[$i]}" + + if [[ "$source" =~ '*' ]]; then + # If the source name contains '*', perform globbing. + mkdir -p $root/$target + for fn in $source; do + rsync -a --no-o --no-g "$fn" $root/$target/ + done + else + mkdir -p $root/$(dirname $target) + if ! [ -e $root/$target ]; then + rsync -a --no-o --no-g $source $root/$target + else + echo "duplicate entry $target -> $source" + exit 1 + fi + fi + done + + export HOME=$TMPDIR + + # Provide a Nix database so that nixos-install can copy closures. + export NIX_STATE_DIR=$TMPDIR/state + nix-store --load-db < ${closureInfo}/registration + + echo "running nixos-install..." + nixos-install --root $root --no-bootloader --no-root-passwd \ + --system ${config.system.build.toplevel} --channel ${channelSources} --substituters "" + + echo "copying staging root to image..." + cptofs -p ${optionalString (partitionTableType != "none") "-P ${rootPartition}"} -t ${fsType} -i $diskImage $root/* / + ''; +in pkgs.vmTools.runInLinuxVM ( + pkgs.runCommand name + { preVM = prepareImage; + buildInputs = with pkgs; [ utillinux e2fsprogs dosfstools ]; + postVM = '' + ${if format == "raw" then '' + mv $diskImage $out/${filename} + '' else '' + ${pkgs.qemu}/bin/qemu-img convert -f raw -O ${format} ${compress} $diskImage $out/${filename} + ''} + diskImage=$out/${filename} + ${postVM} + ''; + memSize = 1024; + } + '' + export PATH=${binPath}:$PATH + + rootDisk=${if partitionTableType != "none" then "/dev/vda${rootPartition}" else "/dev/vda"} + + # Some tools assume these exist + ln -s vda /dev/xvda + ln -s vda /dev/sda + + mountPoint=/mnt + mkdir $mountPoint + mount $rootDisk $mountPoint + + # Create the ESP and mount it. Unlike e2fsprogs, mkfs.vfat doesn't support an + # '-E offset=X' option, so we can't do this outside the VM. + ${optionalString (partitionTableType == "efi") '' + mkdir -p /mnt/boot + mkfs.vfat -n ESP /dev/vda1 + mount /dev/vda1 /mnt/boot + ''} + + # Install a configuration.nix + mkdir -p /mnt/etc/nixos + ${optionalString (configFile != null) '' + cp ${configFile} /mnt/etc/nixos/configuration.nix + ''} + + # Set up core system link, GRUB, etc. + NIXOS_INSTALL_BOOTLOADER=1 nixos-enter --root $mountPoint -- /nix/var/nix/profiles/system/bin/switch-to-configuration boot + + # The above scripts will generate a random machine-id and we don't want to bake a single ID into all our images + rm -f $mountPoint/etc/machine-id + + umount -R /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 + ''} + '' +) |