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