d7ef2defda
As a follow-up to https://github.com/NixOS/nixpkgs/pull/294096 this should further improve the flexibility around building OS images with systemd-repart: * Previously the attribute set `compression` needed to be fully populated, including `algorithm` and `level` because `compression.enable` was evaluated by bash, after being interpolated as strings into the `buildCommand`. Now it's sufficient to pass `compression.enable = false` to the builder, e.g. in `overrideAttrs`, to disable the compression. * Using mkDerivation allows for much more customization than the previously used `runCommand`, making use of phases and pre/post hooks. This is especially helpful for building multiple images from the same system configuration, e.g. to build an image `Y` based on a partially built raw image `X`, by injecting a UKI that depends on `X` into a defered ESP. * Before this change it was non-trivial to conduct further manipulations on the amended repart definitions. Now, the definitions that systemd-repart uses to build the image can be easily manipulated in `postPatch` or `preBuild`. Aside from this, the build is now executed in the build directory, rather than `$out`. This allows references to relative paths in the build environment to be used, especially for `--definitions`, which previously required an absolute path.
163 lines
3.6 KiB
Nix
163 lines
3.6 KiB
Nix
# This is an expression meant to be called from `./repart.nix`, it is NOT a
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# NixOS module that can be imported.
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{ lib
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, stdenvNoCC
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, runCommand
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, python3
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, black
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, ruff
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, mypy
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, systemd
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, fakeroot
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, util-linux
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# filesystem tools
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, dosfstools
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, mtools
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, e2fsprogs
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, squashfsTools
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, erofs-utils
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, btrfs-progs
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, xfsprogs
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# compression tools
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, zstd
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, xz
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# arguments
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, name
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, version
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, imageFileBasename
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, compression
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, fileSystems
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, partitionsJSON
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, split
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, seed
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, definitionsDirectory
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, sectorSize
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, mkfsEnv ? {}
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, createEmpty ? true
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}:
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let
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amendRepartDefinitions = runCommand "amend-repart-definitions.py"
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{
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# TODO: ruff does not splice properly in nativeBuildInputs
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depsBuildBuild = [ ruff ];
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nativeBuildInputs = [ python3 black mypy ];
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} ''
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install ${./amend-repart-definitions.py} $out
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patchShebangs --build $out
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black --check --diff $out
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ruff --line-length 88 $out
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mypy --strict $out
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'';
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fileSystemToolMapping = {
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"vfat" = [ dosfstools mtools ];
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"ext4" = [ e2fsprogs.bin ];
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"squashfs" = [ squashfsTools ];
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"erofs" = [ erofs-utils ];
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"btrfs" = [ btrfs-progs ];
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"xfs" = [ xfsprogs ];
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};
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fileSystemTools = builtins.concatMap (f: fileSystemToolMapping."${f}") fileSystems;
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compressionPkg = {
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"zstd" = zstd;
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"xz" = xz;
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}."${compression.algorithm}";
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compressionCommand = {
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"zstd" = "zstd --no-progress --threads=0 -${toString compression.level}";
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"xz" = "xz --keep --verbose --threads=0 -${toString compression.level}";
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}."${compression.algorithm}";
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in
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stdenvNoCC.mkDerivation (finalAttrs:
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(if (version != null)
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then { pname = name; inherit version; }
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else { inherit name; }
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) // {
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__structuredAttrs = true;
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nativeBuildInputs = [
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systemd
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fakeroot
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util-linux
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] ++ lib.optionals (compression.enable) [
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compressionPkg
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] ++ fileSystemTools;
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env = mkfsEnv;
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inherit partitionsJSON definitionsDirectory;
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# relative path to the repart definitions that are read by systemd-repart
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finalRepartDefinitions = "repart.d";
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systemdRepartFlags = [
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"--dry-run=no"
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"--size=auto"
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"--seed=${seed}"
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"--definitions=${finalAttrs.finalRepartDefinitions}"
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"--split=${lib.boolToString split}"
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"--json=pretty"
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] ++ lib.optionals createEmpty [
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"--empty=create"
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] ++ lib.optionals (sectorSize != null) [
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"--sector-size=${toString sectorSize}"
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];
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dontUnpack = true;
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dontConfigure = true;
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doCheck = false;
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patchPhase = ''
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runHook prePatch
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amendedRepartDefinitionsDir=$(${amendRepartDefinitions} $partitionsJSON $definitionsDirectory)
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ln -vs $amendedRepartDefinitionsDir $finalRepartDefinitions
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runHook postPatch
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'';
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buildPhase = ''
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runHook preBuild
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echo "Building image with systemd-repart..."
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unshare --map-root-user fakeroot systemd-repart \
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''${systemdRepartFlags[@]} \
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${imageFileBasename}.raw \
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| tee repart-output.json
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runHook postBuild
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'';
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installPhase = ''
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runHook preInstall
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mkdir -p $out
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''
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# Compression is implemented in the same derivation as opposed to in a
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# separate derivation to allow users to save disk space. Disk images are
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# already very space intensive so we want to allow users to mitigate this.
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+ lib.optionalString compression.enable
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''
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for f in ${imageFileBasename}*; do
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echo "Compressing $f with ${compression.algorithm}..."
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# Keep the original file when compressing and only delete it afterwards
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${compressionCommand} $f && rm $f
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done
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'' + ''
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mv -v repart-output.json ${imageFileBasename}* $out
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runHook postInstall
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'';
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passthru = {
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inherit amendRepartDefinitions;
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};
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})
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