9ac1ab10c9
This fixes image creation on armv7l when image is bigger than 2G. Also fix some reproducibility issues and other cptofs issues.
86 lines
2.9 KiB
Nix
86 lines
2.9 KiB
Nix
# Builds an ext4 image containing a populated /nix/store with the closure
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# of store paths passed in the storePaths parameter, in addition to the
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# contents of a directory that can be populated with commands. The
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# generated image is sized to only fit its contents, with the expectation
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# that a script resizes the filesystem at boot time.
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{ pkgs
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, lib
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# List of derivations to be included
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, storePaths
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# Whether or not to compress the resulting image with zstd
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, compressImage ? false, zstd
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# Shell commands to populate the ./files directory.
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# All files in that directory are copied to the root of the FS.
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, populateImageCommands ? ""
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, volumeLabel
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, uuid ? "44444444-4444-4444-8888-888888888888"
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, e2fsprogs
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, libfaketime
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, perl
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, fakeroot
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}:
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let
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sdClosureInfo = pkgs.buildPackages.closureInfo { rootPaths = storePaths; };
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in
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pkgs.stdenv.mkDerivation {
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name = "ext4-fs.img${lib.optionalString compressImage ".zst"}";
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nativeBuildInputs = [ e2fsprogs.bin libfaketime perl fakeroot ]
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++ lib.optional compressImage zstd;
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buildCommand =
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''
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${if compressImage then "img=temp.img" else "img=$out"}
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(
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mkdir -p ./files
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${populateImageCommands}
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)
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echo "Preparing store paths for image..."
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# Create nix/store before copying path
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mkdir -p ./rootImage/nix/store
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xargs -I % cp -a --reflink=auto % -t ./rootImage/nix/store/ < ${sdClosureInfo}/store-paths
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(
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GLOBIGNORE=".:.."
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shopt -u dotglob
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cp -a --reflink=auto ./files/* -t ./rootImage/
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)
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# Also include a manifest of the closures in a format suitable for nix-store --load-db
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cp ${sdClosureInfo}/registration ./rootImage/nix-path-registration
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# Make a crude approximation of the size of the target image.
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# If the script starts failing, increase the fudge factors here.
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numInodes=$(find ./rootImage | wc -l)
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numDataBlocks=$(du -s -c -B 4096 --apparent-size ./rootImage | tail -1 | awk '{ print int($1 * 1.10) }')
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bytes=$((2 * 4096 * $numInodes + 4096 * $numDataBlocks))
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echo "Creating an EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks)"
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truncate -s $bytes $img
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faketime -f "1970-01-01 00:00:01" fakeroot mkfs.ext4 -L ${volumeLabel} -U ${uuid} -d ./rootImage $img
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export EXT2FS_NO_MTAB_OK=yes
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# I have ended up with corrupted images sometimes, I suspect that happens when the build machine's disk gets full during the build.
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if ! fsck.ext4 -n -f $img; then
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echo "--- Fsck failed for EXT4 image of $bytes bytes (numInodes=$numInodes, numDataBlocks=$numDataBlocks) ---"
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cat errorlog
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return 1
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fi
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echo "Resizing to minimum allowed size"
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resize2fs -M $img
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# And a final fsck, because of the previous truncating.
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fsck.ext4 -n -f $img
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if [ ${builtins.toString compressImage} ]; then
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echo "Compressing image"
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zstd -v --no-progress ./$img -o $out
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fi
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'';
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}
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