f1708a9d7d
This changes much of the make-disk-image.nix logic (and thus most NixOS image building) to use LKL to set up the target directory structure rather than a Linux VM. The only work we still do in a VM is less IO-heavy stuff that while still time-consuming, is less of the overall load. The goal is to kill more of that stuff, but that will require deeper changes to NixOS activation scripts and switch-to-configuration.pl, and I don't want to bite off too much at once.
198 lines
6.3 KiB
Nix
198 lines
6.3 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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, # Whether the disk should be partitioned (with a single partition
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# containing the root filesystem) or contain the root filesystem
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# directly.
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partitioned ? true
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# Whether to invoke switch-to-configuration boot during image creation
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, installBootLoader ? true
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, # The root file system type.
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fsType ? "ext4"
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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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, format ? "raw"
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}:
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with lib;
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let
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# Copied from https://github.com/NixOS/nixpkgs/blob/master/nixos/modules/installer/cd-dvd/channel.nix
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# TODO: factor out more cleanly
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# Do not include these things:
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# - The '.git' directory
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# - Result symlinks from nix-build ('result', 'result-2', 'result-bin', ...)
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# - VIM/Emacs swap/backup files ('.swp', '.swo', '.foo.swp', 'foo~', ...)
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filterFn = path: type: let basename = baseNameOf (toString path); in
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if type == "directory" then basename != ".git"
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else if type == "symlink" then builtins.match "^result(|-.*)$" basename == null
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else builtins.match "^((|\..*)\.sw[a-z]|.*~)$" basename == null;
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nixpkgs = builtins.filterSource filterFn pkgs.path;
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channelSources = pkgs.runCommand "nixos-${config.system.nixosVersion}" {} ''
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mkdir -p $out
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cp -prd ${nixpkgs} $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.nixosVersionSuffix} > $out/nixos/.version-suffix
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'';
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metaClosure = pkgs.writeText "meta" ''
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${config.system.build.toplevel}
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${config.nix.package.out}
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${channelSources}
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'';
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prepareImageInputs = with pkgs; [ rsync utillinux parted e2fsprogs lkl fakeroot config.system.build.nixos-prepare-root ] ++ 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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prepareImage = ''
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export PATH=${pkgs.lib.makeSearchPathOutput "bin" "bin" prepareImageInputs}
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mkdir $out
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diskImage=nixos.raw
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truncate -s ${toString diskSize}M $diskImage
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${if partitioned then ''
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parted $diskImage -- mklabel msdos mkpart primary ext4 1M -1s
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offset=$((2048*512))
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'' else ''
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offset=0
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''}
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mkfs.${fsType} -F -L nixos -E offset=$offset $diskImage
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root="$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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# TODO: Nix really likes to chown things it creates to its current user...
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fakeroot nixos-prepare-root $root ${channelSources} ${config.system.build.toplevel} closure
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echo "copying staging root to image..."
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cptofs ${pkgs.lib.optionalString partitioned "-P 1"} -t ${fsType} -i $diskImage $root/* /
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'';
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in pkgs.vmTools.runInLinuxVM (
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pkgs.runCommand name
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{ preVM = prepareImage;
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buildInputs = with pkgs; [ utillinux e2fsprogs ];
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exportReferencesGraph = [ "closure" metaClosure ];
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postVM = ''
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${if format == "raw" then ''
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mv $diskImage $out/nixos.img
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diskImage=$out/nixos.img
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'' else ''
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${pkgs.qemu}/bin/qemu-img convert -f raw -O qcow2 $diskImage $out/nixos.qcow2
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diskImage=$out/nixos.qcow2
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''}
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${postVM}
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'';
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memSize = 1024;
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}
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''
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${if partitioned then ''
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. /sys/class/block/vda1/uevent
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mknod /dev/vda1 b $MAJOR $MINOR
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rootDisk=/dev/vda1
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'' else ''
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rootDisk=/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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mountPoint=/mnt
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mkdir $mountPoint
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mount $rootDisk $mountPoint
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# Install a configuration.nix
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mkdir -p /mnt/etc/nixos
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${optionalString (configFile != null) ''
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cp ${configFile} /mnt/etc/nixos/configuration.nix
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''}
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mount --rbind /dev $mountPoint/dev
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mount --rbind /proc $mountPoint/proc
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mount --rbind /sys $mountPoint/sys
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# Set up core system link, GRUB, etc.
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NIXOS_INSTALL_BOOTLOADER=1 chroot $mountPoint /nix/var/nix/profiles/system/bin/switch-to-configuration boot
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# TODO: figure out if I should activate, but for now I won't
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# chroot $mountPoint /nix/var/nix/profiles/system/activate
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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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