This reverts commit e9bf955fd6d5ffda218878ba561c93c6a28dfe8e. We use nixos-install to ensure that make-disk-image produces the same result as a regular installation (9802da517fe4da41d68516029b01c5c1f175b3e4) and to reduce code duplication. If there is something broken in nixos-install, it should be fixed there.
		
			
				
	
	
		
			248 lines
		
	
	
		
			7.7 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			248 lines
		
	
	
		
			7.7 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ pkgs
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, lib
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, # The NixOS configuration to be installed onto the disk image.
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  config
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, # The size of the disk, in megabytes.
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  diskSize
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  # The files and directories to be placed in the target file system.
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  # This is a list of attribute sets {source, target} where `source'
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  # is the file system object (regular file or directory) to be
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  # grafted in the file system at path `target'.
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, contents ? []
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, # Type of partition table to use; either "legacy", "efi", or "none".
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  # For "efi" images, the GPT partition table is used and a mandatory ESP
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  #   partition of reasonable size is created in addition to the root partition.
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  #   If `installBootLoader` is true, GRUB will be installed in EFI mode.
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  # For "legacy", the msdos partition table is used and a single large root
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  #   partition is created. If `installBootLoader` is true, GRUB will be
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  #   installed in legacy mode.
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  # For "none", no partition table is created. Enabling `installBootLoader`
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  #   most likely fails as GRUB will probably refuse to install.
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  partitionTableType ? "legacy"
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, # The root file system type.
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  fsType ? "ext4"
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, # Filesystem label
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  label ? "nixos"
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, # The initial NixOS configuration file to be copied to
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  # /etc/nixos/configuration.nix.
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  configFile ? null
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, # Shell code executed after the VM has finished.
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  postVM ? ""
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, name ? "nixos-disk-image"
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, # Disk image format, one of qcow2, qcow2-compressed, vpc, raw.
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  format ? "raw"
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}:
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assert partitionTableType == "legacy" || partitionTableType == "efi" || partitionTableType == "none";
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# We use -E offset=X below, which is only supported by e2fsprogs
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assert partitionTableType != "none" -> fsType == "ext4";
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with lib;
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let format' = format; in let
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  format = if format' == "qcow2-compressed" then "qcow2" else format';
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  compress = optionalString (format' == "qcow2-compressed") "-c";
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  filename = "nixos." + {
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    qcow2 = "qcow2";
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    vpc   = "vhd";
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    raw   = "img";
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  }.${format};
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  rootPartition = { # switch-case
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    legacy = "1";
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    efi = "2";
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  }.${partitionTableType};
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  partitionDiskScript = { # switch-case
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    legacy = ''
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      parted --script $diskImage -- \
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        mklabel msdos \
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        mkpart primary ext4 1MiB -1
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    '';
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    efi = ''
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      parted --script $diskImage -- \
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        mklabel gpt \
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        mkpart ESP fat32 8MiB 256MiB \
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        set 1 boot on \
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        mkpart primary ext4 256MiB -1
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    '';
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    none = "";
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  }.${partitionTableType};
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  nixpkgs = cleanSource pkgs.path;
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  # FIXME: merge with channel.nix / make-channel.nix.
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  channelSources = pkgs.runCommand "nixos-${config.system.nixos.version}" {} ''
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    mkdir -p $out
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    cp -prd ${nixpkgs.outPath} $out/nixos
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    chmod -R u+w $out/nixos
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    if [ ! -e $out/nixos/nixpkgs ]; then
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      ln -s . $out/nixos/nixpkgs
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    fi
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    rm -rf $out/nixos/.git
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    echo -n ${config.system.nixos.versionSuffix} > $out/nixos/.version-suffix
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  '';
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  binPath = with pkgs; makeBinPath (
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    [ rsync
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      utillinux
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      parted
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      e2fsprogs
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      lkl
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      config.system.build.nixos-install
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      config.system.build.nixos-enter
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      nix
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    ] ++ stdenv.initialPath);
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  # I'm preserving the line below because I'm going to search for it across nixpkgs to consolidate
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  # image building logic. The comment right below this now appears in 4 different places in nixpkgs :)
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  # !!! should use XML.
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  sources = map (x: x.source) contents;
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  targets = map (x: x.target) contents;
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  closureInfo = pkgs.closureInfo { rootPaths = [ config.system.build.toplevel channelSources ]; };
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  prepareImage = ''
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    export PATH=${binPath}
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    # Yes, mkfs.ext4 takes different units in different contexts. Fun.
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    sectorsToKilobytes() {
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      echo $(( ( "$1" * 512 ) / 1024 ))
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    }
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    sectorsToBytes() {
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      echo $(( "$1" * 512  ))
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    }
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    mkdir $out
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    diskImage=nixos.raw
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    truncate -s ${toString diskSize}M $diskImage
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    ${partitionDiskScript}
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    ${if partitionTableType != "none" then ''
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      # Get start & length of the root partition in sectors to $START and $SECTORS.
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      eval $(partx $diskImage -o START,SECTORS --nr ${rootPartition} --pairs)
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      mkfs.${fsType} -F -L ${label} $diskImage -E offset=$(sectorsToBytes $START) $(sectorsToKilobytes $SECTORS)K
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    '' else ''
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      mkfs.${fsType} -F -L ${label} $diskImage
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    ''}
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    root="$PWD/root"
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    mkdir -p $root
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    # Copy arbitrary other files into the image
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    # Semi-shamelessly copied from make-etc.sh. I (@copumpkin) shall factor this stuff out as part of
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    # https://github.com/NixOS/nixpkgs/issues/23052.
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    set -f
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    sources_=(${concatStringsSep " " sources})
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    targets_=(${concatStringsSep " " targets})
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    set +f
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    for ((i = 0; i < ''${#targets_[@]}; i++)); do
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      source="''${sources_[$i]}"
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      target="''${targets_[$i]}"
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      if [[ "$source" =~ '*' ]]; then
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        # If the source name contains '*', perform globbing.
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        mkdir -p $root/$target
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        for fn in $source; do
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          rsync -a --no-o --no-g "$fn" $root/$target/
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        done
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      else
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        mkdir -p $root/$(dirname $target)
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        if ! [ -e $root/$target ]; then
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          rsync -a --no-o --no-g $source $root/$target
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        else
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          echo "duplicate entry $target -> $source"
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          exit 1
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        fi
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      fi
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    done
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    export HOME=$TMPDIR
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    # Provide a Nix database so that nixos-install can copy closures.
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    export NIX_STATE_DIR=$TMPDIR/state
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    nix-store --load-db < ${closureInfo}/registration
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    echo "running nixos-install..."
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    nixos-install --root $root --no-bootloader --no-root-passwd \
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      --system ${config.system.build.toplevel} --channel ${channelSources} --substituters ""
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    echo "copying staging root to image..."
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    cptofs -p ${optionalString (partitionTableType != "none") "-P ${rootPartition}"} -t ${fsType} -i $diskImage $root/* /
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  '';
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in pkgs.vmTools.runInLinuxVM (
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  pkgs.runCommand name
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    { preVM = prepareImage;
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      buildInputs = with pkgs; [ utillinux e2fsprogs dosfstools ];
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      postVM = ''
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        ${if format == "raw" then ''
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          mv $diskImage $out/${filename}
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        '' else ''
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          ${pkgs.qemu}/bin/qemu-img convert -f raw -O ${format} ${compress} $diskImage $out/${filename}
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        ''}
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        diskImage=$out/${filename}
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        ${postVM}
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      '';
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      memSize = 1024;
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    }
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    ''
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      export PATH=${binPath}:$PATH
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      rootDisk=${if partitionTableType != "none" then "/dev/vda${rootPartition}" else "/dev/vda"}
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      # Some tools assume these exist
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      ln -s vda /dev/xvda
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      ln -s vda /dev/sda
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      mountPoint=/mnt
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      mkdir $mountPoint
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      mount $rootDisk $mountPoint
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      # Create the ESP and mount it. Unlike e2fsprogs, mkfs.vfat doesn't support an
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      # '-E offset=X' option, so we can't do this outside the VM.
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      ${optionalString (partitionTableType == "efi") ''
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        mkdir -p /mnt/boot
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        mkfs.vfat -n ESP /dev/vda1
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        mount /dev/vda1 /mnt/boot
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      ''}
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      # Install a configuration.nix
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      mkdir -p /mnt/etc/nixos
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      ${optionalString (configFile != null) ''
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        cp ${configFile} /mnt/etc/nixos/configuration.nix
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      ''}
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      # Set up core system link, GRUB, etc.
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      NIXOS_INSTALL_BOOTLOADER=1 nixos-enter --root $mountPoint -- /nix/var/nix/profiles/system/bin/switch-to-configuration boot
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      # The above scripts will generate a random machine-id and we don't want to bake a single ID into all our images
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      rm -f $mountPoint/etc/machine-id
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      umount -R /mnt
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      # Make sure resize2fs works. Note that resize2fs has stricter criteria for resizing than a normal
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      # mount, so the `-c 0` and `-i 0` don't affect it. Setting it to `now` doesn't produce deterministic
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      # output, of course, but we can fix that when/if we start making images deterministic.
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      ${optionalString (fsType == "ext4") ''
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        tune2fs -T now -c 0 -i 0 $rootDisk
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      ''}
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    ''
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)
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