53 lines
1.6 KiB
Bash
Executable file
53 lines
1.6 KiB
Bash
Executable file
#!@shell@
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set -eu
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layerNumber=$1
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shift
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layerPath="./layers/$layerNumber"
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echo "Creating layer #$layerNumber for $@"
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mkdir -p "$layerPath"
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# Make sure /nix and /nix/store appear first in the archive.
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# We create the directories here and use them because
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# when there are other things being added to the
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# nix store, tar could fail, saying,
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# "tar: /nix/store: file changed as we read it"
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mkdir -p nix/store
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tar -cf "$layerPath/layer.tar" \
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--mtime="@$SOURCE_DATE_EPOCH" \
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--owner=0 --group=0 \
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--transform='s,nix,/nix,' \
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nix
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# We change into the /nix/store in order to avoid a similar
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# "file changed as we read it" error as above. Namely,
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# if we use the absolute path of /nix/store/123-pkg
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# and something new is added to the nix store while tar
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# is running, it will detect a change to /nix/store and
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# fail. Instead, if we cd into the nix store and copy
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# the relative nix store path, tar will ignore changes
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# to /nix/store. In order to create the correct structure
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# in the tar file, we transform the relative nix store
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# path to the absolute store path.
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for storePath in "$@"; do
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n=$(basename "$storePath")
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tar -C /nix/store -rpf "$layerPath/layer.tar" \
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--hard-dereference --sort=name \
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--mtime="@$SOURCE_DATE_EPOCH" \
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--owner=0 --group=0 \
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--transform="s,$n,/nix/store/$n," \
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$n
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done
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# Compute a checksum of the tarball.
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tarhash=$(tarsum < $layerPath/layer.tar)
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# Add a 'checksum' field to the JSON, with the value set to the
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# checksum of the tarball.
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cat ./generic.json | jshon -s "$tarhash" -i checksum > $layerPath/json
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# Indicate to docker that we're using schema version 1.0.
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echo -n "1.0" > $layerPath/VERSION
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