mirror of
https://github.com/NixOS/nixpkgs.git
synced 2024-11-22 15:03:28 +00:00
96 lines
3.3 KiB
Nix
96 lines
3.3 KiB
Nix
# Builds an ext4 image containing a populated /nix/store with the closure
|
|
# of store paths passed in the storePaths parameter, in addition to the
|
|
# contents of a directory that can be populated with commands. The
|
|
# generated image is sized to only fit its contents, with the expectation
|
|
# that a script resizes the filesystem at boot time.
|
|
{ pkgs
|
|
, lib
|
|
# List of derivations to be included
|
|
, storePaths
|
|
# Whether or not to compress the resulting image with zstd
|
|
, compressImage ? false, zstd
|
|
# Shell commands to populate the ./files directory.
|
|
# All files in that directory are copied to the root of the FS.
|
|
, populateImageCommands ? ""
|
|
, volumeLabel
|
|
, uuid ? "44444444-4444-4444-8888-888888888888"
|
|
, e2fsprogs
|
|
, libfaketime
|
|
, perl
|
|
, fakeroot
|
|
}:
|
|
|
|
let
|
|
sdClosureInfo = pkgs.buildPackages.closureInfo { rootPaths = storePaths; };
|
|
in
|
|
pkgs.stdenv.mkDerivation {
|
|
name = "ext4-fs.img${lib.optionalString compressImage ".zst"}";
|
|
|
|
nativeBuildInputs = [ e2fsprogs.bin libfaketime perl fakeroot ]
|
|
++ lib.optional compressImage zstd;
|
|
|
|
buildCommand =
|
|
''
|
|
${if compressImage then "img=temp.img" else "img=$out"}
|
|
(
|
|
mkdir -p ./files
|
|
${populateImageCommands}
|
|
)
|
|
|
|
echo "Preparing store paths for image..."
|
|
|
|
# Create nix/store before copying path
|
|
mkdir -p ./rootImage/nix/store
|
|
|
|
xargs -I % cp -a --reflink=auto % -t ./rootImage/nix/store/ < ${sdClosureInfo}/store-paths
|
|
(
|
|
GLOBIGNORE=".:.."
|
|
shopt -u dotglob
|
|
|
|
for f in ./files/*; do
|
|
cp -a --reflink=auto -t ./rootImage/ "$f"
|
|
done
|
|
)
|
|
|
|
# Also include a manifest of the closures in a format suitable for nix-store --load-db
|
|
cp ${sdClosureInfo}/registration ./rootImage/nix-path-registration
|
|
|
|
# Make a crude approximation of the size of the target image.
|
|
# If the script starts failing, increase the fudge factors here.
|
|
numInodes=$(find ./rootImage | wc -l)
|
|
numDataBlocks=$(du -s -c -B 4096 --apparent-size ./rootImage | tail -1 | awk '{ print int($1 * 1.10) }')
|
|
bytes=$((2 * 4096 * $numInodes + 4096 * $numDataBlocks))
|
|
echo "Creating an EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks)"
|
|
|
|
truncate -s $bytes $img
|
|
|
|
faketime -f "1970-01-01 00:00:01" fakeroot mkfs.ext4 -L ${volumeLabel} -U ${uuid} -d ./rootImage $img
|
|
|
|
export EXT2FS_NO_MTAB_OK=yes
|
|
# I have ended up with corrupted images sometimes, I suspect that happens when the build machine's disk gets full during the build.
|
|
if ! fsck.ext4 -n -f $img; then
|
|
echo "--- Fsck failed for EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks) ---"
|
|
cat errorlog
|
|
return 1
|
|
fi
|
|
|
|
# We may want to shrink the file system and resize the image to
|
|
# get rid of the unnecessary slack here--but see
|
|
# https://github.com/NixOS/nixpkgs/issues/125121 for caveats.
|
|
|
|
# shrink to fit
|
|
resize2fs -M $img
|
|
|
|
# Add 16 MebiByte to the current_size
|
|
new_size=$(dumpe2fs -h $img | awk -F: \
|
|
'/Block count/{count=$2} /Block size/{size=$2} END{print (count*size+16*2**20)/size}')
|
|
|
|
resize2fs $img $new_size
|
|
|
|
if [ ${builtins.toString compressImage} ]; then
|
|
echo "Compressing image"
|
|
zstd -v --no-progress ./$img -o $out
|
|
fi
|
|
'';
|
|
}
|