335 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			335 lines
		
	
	
		
			11 KiB
		
	
	
	
		
			Nix
		
	
	
	
	
	
| { pkgs
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| , lib
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| 
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| , # The NixOS configuration to be installed onto the disk image.
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|   config
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| 
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| , # The size of the disk, in megabytes.
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|   # if "auto" size is calculated based on the contents copied to it and
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|   #   additionalSpace is taken into account.
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|   diskSize ? "auto"
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| 
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| , # additional disk space to be added to the image if diskSize "auto"
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|   # is used
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|   additionalSpace ? "512M"
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| 
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| , # size of the boot partition, is only used if partitionTableType is
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|   # either "efi" or "hybrid"
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|   bootSize ? "256M"
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| 
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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, mode, user, group} where
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|   # `source' is the file system object (regular file or directory) to be
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|   # grafted in the file system at path `target', `mode' is a string containing
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|   # the permissions that will be set (ex. "755"), `user' and `group' are the
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|   # user and group name that will be set as owner of the files.
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|   # `mode', `user', and `group' are optional.
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|   # When setting one of `user' or `group', the other needs to be set too.
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|   contents ? []
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| 
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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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|   # For "legacy", the msdos partition table is used and a single large root
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|   #   partition is created.
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|   # For "legacy+gpt", the GPT partition table is used, a 1MiB no-fs partition for
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|   #   use by the bootloader is created, and a single large root partition is
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|   #   created.
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|   # For "hybrid", 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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|   #   Also a legacy MBR will be present.
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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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| 
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| , # The root file system type.
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|   fsType ? "ext4"
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| 
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| , # Filesystem label
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|   label ? "nixos"
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| 
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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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| 
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| , # Shell code executed after the VM has finished.
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|   postVM ? ""
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| 
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| , name ? "nixos-disk-image"
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| 
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| , # Disk image format, one of qcow2, qcow2-compressed, vdi, vpc, raw.
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|   format ? "raw"
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| }:
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| 
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| assert partitionTableType == "legacy" || partitionTableType == "legacy+gpt" || partitionTableType == "efi" || partitionTableType == "hybrid" || 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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| # Either both or none of {user,group} need to be set
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| assert lib.all
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|          (attrs: ((attrs.user  or null) == null)
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|               == ((attrs.group or null) == null))
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|          contents;
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| 
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| with lib;
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| 
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| let format' = format; in let
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| 
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|   format = if format' == "qcow2-compressed" then "qcow2" else format';
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| 
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|   compress = optionalString (format' == "qcow2-compressed") "-c";
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| 
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|   filename = "nixos." + {
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|     qcow2 = "qcow2";
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|     vdi   = "vdi";
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|     vpc   = "vhd";
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|     raw   = "img";
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|   }.${format} or format;
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| 
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|   rootPartition = { # switch-case
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|     legacy = "1";
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|     "legacy+gpt" = "2";
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|     efi = "2";
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|     hybrid = "3";
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|   }.${partitionTableType};
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| 
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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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|     "legacy+gpt" = ''
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|       parted --script $diskImage -- \
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|         mklabel gpt \
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|         mkpart no-fs 1MB 2MB \
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|         set 1 bios_grub on \
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|         align-check optimal 1 \
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|         mkpart primary ext4 2MB -1 \
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|         align-check optimal 2 \
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|         print
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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 ${bootSize} \
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|         set 1 boot on \
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|         mkpart primary ext4 ${bootSize} -1
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|     '';
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|     hybrid = ''
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|       parted --script $diskImage -- \
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|         mklabel gpt \
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|         mkpart ESP fat32 8MiB ${bootSize} \
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|         set 1 boot on \
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|         mkpart no-fs 0 1024KiB \
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|         set 2 bios_grub on \
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|         mkpart primary ext4 ${bootSize} -1
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|     '';
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|     none = "";
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|   }.${partitionTableType};
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| 
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|   nixpkgs = cleanSource pkgs.path;
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| 
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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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| 
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|   binPath = with pkgs; makeBinPath (
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|     [ rsync
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|       util-linux
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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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| 
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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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|   modes   = map (x: x.mode  or "''") contents;
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|   users   = map (x: x.user  or "''") contents;
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|   groups  = map (x: x.group or "''") contents;
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| 
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|   closureInfo = pkgs.closureInfo { rootPaths = [ config.system.build.toplevel channelSources ]; };
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| 
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|   prepareImage = ''
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|     export PATH=${binPath}
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| 
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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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| 
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|     sectorsToBytes() {
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|       echo $(( "$1" * 512  ))
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|     }
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| 
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|     mkdir $out
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| 
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|     root="$PWD/root"
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|     mkdir -p $root
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| 
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|     # Copy arbitrary other files into the image
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|     # Semi-shamelessly copied from make-etc.sh. I (@copumpkin) shall factor this stuff out as part of
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|     # https://github.com/NixOS/nixpkgs/issues/23052.
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|     set -f
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|     sources_=(${concatStringsSep " " sources})
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|     targets_=(${concatStringsSep " " targets})
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|     modes_=(${concatStringsSep " " modes})
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|     set +f
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| 
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|     for ((i = 0; i < ''${#targets_[@]}; i++)); do
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|       source="''${sources_[$i]}"
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|       target="''${targets_[$i]}"
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|       mode="''${modes_[$i]}"
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| 
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|       if [ -n "$mode" ]; then
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|         rsync_chmod_flags="--chmod=$mode"
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|       else
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|         rsync_chmod_flags=""
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|       fi
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|       # Unfortunately cptofs only supports modes, not ownership, so we can't use
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|       # rsync's --chown option. Instead, we change the ownerships in the
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|       # VM script with chown.
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|       rsync_flags="-a --no-o --no-g $rsync_chmod_flags"
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|       if [[ "$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 $rsync_flags "$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 $rsync_flags $source $root/$target
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|         else
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|           echo "duplicate entry $target -> $source"
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|           exit 1
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|         fi
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|       fi
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|     done
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| 
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|     export HOME=$TMPDIR
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| 
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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 < ${closureInfo}/registration
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| 
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|     chmod 755 "$TMPDIR"
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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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| 
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|     diskImage=nixos.raw
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| 
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|     ${if diskSize == "auto" then ''
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|       ${if partitionTableType == "efi" || partitionTableType == "hybrid" then ''
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|         additionalSpace=$(( ($(numfmt --from=iec '${additionalSpace}') + $(numfmt --from=iec '${bootSize}')) / 1000 ))
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|       '' else ''
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|         additionalSpace=$(( $(numfmt --from=iec '${additionalSpace}') / 1000 ))
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|       ''}
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|       diskSize=$(( $(set -- $(du -d0 $root); echo "$1") + $additionalSpace ))
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|       truncate -s "$diskSize"K $diskImage
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|     '' else ''
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|       truncate -s ${toString diskSize}M $diskImage
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|     ''}
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| 
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|     ${partitionDiskScript}
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| 
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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 ${rootPartition} --pairs)
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| 
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|       mkfs.${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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| 
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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; [ util-linux 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}:$PATH
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| 
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|       rootDisk=${if partitionTableType != "none" then "/dev/vda${rootPartition}" else "/dev/vda"}
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| 
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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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| 
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|       mountPoint=/mnt
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|       mkdir $mountPoint
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|       mount $rootDisk $mountPoint
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| 
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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" || partitionTableType == "hybrid") ''
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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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| 
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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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| 
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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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| 
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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 $mountPoint/etc/machine-id
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| 
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|       # Set the ownerships of the contents. The modes are set in preVM.
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|       # No globbing on targets, so no need to set -f
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|       targets_=(${concatStringsSep " " targets})
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|       users_=(${concatStringsSep " " users})
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|       groups_=(${concatStringsSep " " groups})
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|       for ((i = 0; i < ''${#targets_[@]}; i++)); do
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|         target="''${targets_[$i]}"
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|         user="''${users_[$i]}"
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|         group="''${groups_[$i]}"
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|         if [ -n "$user$group" ]; then
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|           # We have to nixos-enter since we need to use the user and group of the VM
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|           nixos-enter --root $mountPoint -- chown -R "$user:$group" "$target"
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|         fi
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|       done
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| 
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|       umount -R /mnt
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| 
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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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