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dockerTools: Calculate tarsum's on the fly

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Calculating the tarsum after creating a layer is inefficient, since
we have to read the tarball we've just written from the disk.

This commit simultaneously calculates the tarsum while creating the
tarball.
This commit is contained in:
Utku Demir
2020-05-07 11:50:07 +12:00
parent 69f6294724
commit f12346d493
2 changed files with 29 additions and 40 deletions
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pkgs/build-support/docker/default.nix
+6 -15
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@@ -392,14 +392,10 @@ rec {
(cd layer; eval "$extraCommands")
fi
# Tar up the layer and throw it into 'layer.tar'.
# Tar up the layer and throw it into 'layer.tar', while calculating its checksum.
echo "Packing layer..."
mkdir $out
tar --transform='s|^\./||' -C layer --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
# Compute a checksum of the tarball.
echo "Computing layer checksum..."
tarhash=$(tarsum < $out/layer.tar)
tarhash=$(tar --transform='s|^\./||' -C layer --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf - . | tee $out/layer.tar | tarsum)
# Add a 'checksum' field to the JSON, with the value set to the
# checksum of the tarball.
@@ -449,11 +445,7 @@ rec {
# Tar up the layer and throw it into 'layer.tar'.
echo "Packing layer..."
mkdir $out
tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
# Compute a checksum of the tarball.
echo "Computing layer checksum..."
tarhash=$(tarsum < $out/layer.tar)
tarhash=$(tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf - . | tee $out/layer.tar | tarsum)
# Add a 'checksum' field to the JSON, with the value set to the
# checksum of the tarball.
@@ -537,11 +529,10 @@ rec {
echo "Packing layer..."
mkdir -p $out
tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf $out/layer.tar .
tarhash=$(tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf - . |
tee $out/layer.tar |
${tarsum}/bin/tarsum)
# Compute the tar checksum and add it to the output json.
echo "Computing checksum..."
tarhash=$(${tarsum}/bin/tarsum < $out/layer.tar)
cat ${baseJson} | jshon -s "$tarhash" -i checksum > $out/json
# Indicate to docker that we're using schema version 1.0.
echo -n "1.0" > $out/VERSION