nixpkgs/pkgs/build-support/docker/default.nix
Antoine Eiche 9082b66096 dockerTools: fix permissions on base image
If the base image has been built with nixpkgs.dockerTools, the image
configuration and manifest are readonly so we first need to change
their permissions before removing them.

Fix #27632.
2017-07-31 13:52:35 +02:00

528 lines
16 KiB
Nix

{
callPackage,
coreutils,
docker,
e2fsprogs,
findutils,
go,
jshon,
jq,
lib,
pkgs,
pigz,
runCommand,
rsync,
shadow,
stdenv,
storeDir ? builtins.storeDir,
utillinux,
vmTools,
writeReferencesToFile,
writeScript,
writeText,
}:
# WARNING: this API is unstable and may be subject to backwards-incompatible changes in the future.
rec {
examples = import ./examples.nix {
inherit pkgs buildImage pullImage shadowSetup;
};
pullImage = callPackage ./pull.nix {};
# We need to sum layer.tar, not a directory, hence tarsum instead of nix-hash.
# And we cannot untar it, because then we cannot preserve permissions ecc.
tarsum = runCommand "tarsum" {
buildInputs = [ go ];
} ''
mkdir tarsum
cd tarsum
cp ${./tarsum.go} tarsum.go
export GOPATH=$(pwd)
mkdir src
ln -sT ${docker.src}/components/engine/pkg/tarsum src/tarsum
go build
cp tarsum $out
'';
# buildEnv creates symlinks to dirs, which is hard to edit inside the overlay VM
mergeDrvs = {
derivations,
onlyDeps ? false
}:
runCommand "merge-drvs" {
inherit derivations onlyDeps;
} ''
if [[ -n "$onlyDeps" ]]; then
echo $derivations > $out
exit 0
fi
mkdir $out
for derivation in $derivations; do
echo "Merging $derivation..."
if [[ -d "$derivation" ]]; then
# If it's a directory, copy all of its contents into $out.
cp -drf --preserve=mode -f $derivation/* $out/
else
# Otherwise treat the derivation as a tarball and extract it
# into $out.
tar -C $out -xpf $drv || true
fi
done
'';
# Helper for setting up the base files for managing users and
# groups, only if such files don't exist already. It is suitable for
# being used in a runAsRoot script.
shadowSetup = ''
export PATH=${shadow}/bin:$PATH
mkdir -p /etc/pam.d
if [[ ! -f /etc/passwd ]]; then
echo "root:x:0:0::/root:${stdenv.shell}" > /etc/passwd
echo "root:!x:::::::" > /etc/shadow
fi
if [[ ! -f /etc/group ]]; then
echo "root:x:0:" > /etc/group
echo "root:x::" > /etc/gshadow
fi
if [[ ! -f /etc/pam.d/other ]]; then
cat > /etc/pam.d/other <<EOF
account sufficient pam_unix.so
auth sufficient pam_rootok.so
password requisite pam_unix.so nullok sha512
session required pam_unix.so
EOF
fi
if [[ ! -f /etc/login.defs ]]; then
touch /etc/login.defs
fi
'';
# Run commands in a virtual machine.
runWithOverlay = {
name,
fromImage ? null,
fromImageName ? null,
fromImageTag ? null,
diskSize ? 1024,
preMount ? "",
postMount ? "",
postUmount ? ""
}:
vmTools.runInLinuxVM (
runCommand name {
preVM = vmTools.createEmptyImage {
size = diskSize;
fullName = "docker-run-disk";
};
inherit fromImage fromImageName fromImageTag;
buildInputs = [ utillinux e2fsprogs jshon rsync ];
} ''
rm -rf $out
mkdir disk
mkfs /dev/${vmTools.hd}
mount /dev/${vmTools.hd} disk
cd disk
if [[ -n "$fromImage" ]]; then
echo "Unpacking base image..."
mkdir image
tar -C image -xpf "$fromImage"
# If the image name isn't set, read it from the image repository json.
if [[ -z "$fromImageName" ]]; then
fromImageName=$(jshon -k < image/repositories | head -n 1)
echo "From-image name wasn't set. Read $fromImageName."
fi
# If the tag isn't set, use the name as an index into the json
# and read the first key found.
if [[ -z "$fromImageTag" ]]; then
fromImageTag=$(jshon -e $fromImageName -k < image/repositories \
| head -n1)
echo "From-image tag wasn't set. Read $fromImageTag."
fi
# Use the name and tag to get the parent ID field.
parentID=$(jshon -e $fromImageName -e $fromImageTag -u \
< image/repositories)
fi
# Unpack all of the parent layers into the image.
lowerdir=""
while [[ -n "$parentID" ]]; do
echo "Unpacking layer $parentID"
mkdir -p image/$parentID/layer
tar -C image/$parentID/layer -xpf image/$parentID/layer.tar
rm image/$parentID/layer.tar
find image/$parentID/layer -name ".wh.*" -exec bash -c 'name="$(basename {}|sed "s/^.wh.//")"; mknod "$(dirname {})/$name" c 0 0; rm {}' \;
# Get the next lower directory and continue the loop.
lowerdir=$lowerdir''${lowerdir:+:}image/$parentID/layer
parentID=$(cat image/$parentID/json \
| (jshon -e parent -u 2>/dev/null || true))
done
mkdir work
mkdir layer
mkdir mnt
${lib.optionalString (preMount != "") ''
# Execute pre-mount steps
echo "Executing pre-mount steps..."
${preMount}
''}
if [ -n "$lowerdir" ]; then
mount -t overlay overlay -olowerdir=$lowerdir,workdir=work,upperdir=layer mnt
else
mount --bind layer mnt
fi
${lib.optionalString (postMount != "") ''
# Execute post-mount steps
echo "Executing post-mount steps..."
${postMount}
''}
umount mnt
(
cd layer
cmd='name="$(basename {})"; touch "$(dirname {})/.wh.$name"; rm "{}"'
find . -type c -exec bash -c "$cmd" \;
)
${postUmount}
'');
exportImage = { name ? fromImage.name, fromImage, fromImageName ? null, fromImageTag ? null, diskSize ? 1024 }:
runWithOverlay {
inherit name fromImage fromImageName fromImageTag diskSize;
postMount = ''
echo "Packing raw image..."
tar -C mnt --mtime="@$SOURCE_DATE_EPOCH" -cf $out .
'';
};
# Create an executable shell script which has the coreutils in its
# PATH. Since root scripts are executed in a blank environment, even
# things like `ls` or `echo` will be missing.
shellScript = name: text:
writeScript name ''
#!${stdenv.shell}
set -e
export PATH=${coreutils}/bin:/bin
${text}
'';
# Create a "layer" (set of files).
mkPureLayer = {
# Name of the layer
name,
# JSON containing configuration and metadata for this layer.
baseJson,
# Files to add to the layer.
contents ? null,
# Additional commands to run on the layer before it is tar'd up.
extraCommands ? "", uid ? 0, gid ? 0
}:
runCommand "docker-layer-${name}" {
inherit baseJson contents extraCommands;
buildInputs = [ jshon rsync ];
}
''
mkdir layer
if [[ -n "$contents" ]]; then
echo "Adding contents..."
for item in $contents; do
echo "Adding $item"
rsync -ak --chown=0:0 $item/ layer/
done
else
echo "No contents to add to layer."
fi
chmod ug+w layer
if [[ -n $extraCommands ]]; then
(cd layer; eval "$extraCommands")
fi
# Tar up the layer and throw it into 'layer.tar'.
echo "Packing layer..."
mkdir $out
tar -C layer --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
# Compute a checksum of the tarball.
echo "Computing layer checksum..."
tarsum=$(${tarsum} < $out/layer.tar)
# Add a 'checksum' field to the JSON, with the value set to the
# checksum of the tarball.
cat ${baseJson} | jshon -s "$tarsum" -i checksum > $out/json
# Indicate to docker that we're using schema version 1.0.
echo -n "1.0" > $out/VERSION
echo "Finished building layer '${name}'"
'';
# Make a "root" layer; required if we need to execute commands as a
# privileged user on the image. The commands themselves will be
# performed in a virtual machine sandbox.
mkRootLayer = {
# Name of the image.
name,
# Script to run as root. Bash.
runAsRoot,
# Files to add to the layer. If null, an empty layer will be created.
contents ? null,
# JSON containing configuration and metadata for this layer.
baseJson,
# Existing image onto which to append the new layer.
fromImage ? null,
# Name of the image we're appending onto.
fromImageName ? null,
# Tag of the image we're appending onto.
fromImageTag ? null,
# How much disk to allocate for the temporary virtual machine.
diskSize ? 1024,
# Commands (bash) to run on the layer; these do not require sudo.
extraCommands ? ""
}:
# Generate an executable script from the `runAsRoot` text.
let runAsRootScript = shellScript "run-as-root.sh" runAsRoot;
in runWithOverlay {
name = "docker-layer-${name}";
inherit fromImage fromImageName fromImageTag diskSize;
preMount = lib.optionalString (contents != null && contents != []) ''
echo "Adding contents..."
for item in ${toString contents}; do
echo "Adding $item..."
rsync -ak --chown=0:0 $item/ layer/
done
chmod ug+w layer
'';
postMount = ''
mkdir -p mnt/{dev,proc,sys} mnt${storeDir}
# Mount /dev, /sys and the nix store as shared folders.
mount --rbind /dev mnt/dev
mount --rbind /sys mnt/sys
mount --rbind ${storeDir} mnt${storeDir}
# Execute the run as root script. See 'man unshare' for
# details on what's going on here; basically this command
# means that the runAsRootScript will be executed in a nearly
# completely isolated environment.
unshare -imnpuf --mount-proc chroot mnt ${runAsRootScript}
# Unmount directories and remove them.
umount -R mnt/dev mnt/sys mnt${storeDir}
rmdir --ignore-fail-on-non-empty \
mnt/dev mnt/proc mnt/sys mnt${storeDir} \
mnt$(dirname ${storeDir})
'';
postUmount = ''
(cd layer; eval "${extraCommands}")
echo "Packing layer..."
mkdir $out
tar -C layer --mtime="@$SOURCE_DATE_EPOCH" -cf $out/layer.tar .
# Compute the tar checksum and add it to the output json.
echo "Computing checksum..."
ts=$(${tarsum} < $out/layer.tar)
cat ${baseJson} | jshon -s "$ts" -i checksum > $out/json
# Indicate to docker that we're using schema version 1.0.
echo -n "1.0" > $out/VERSION
echo "Finished building layer '${name}'"
'';
};
# 1. extract the base image
# 2. create the layer
# 3. add layer deps to the layer itself, diffing with the base image
# 4. compute the layer id
# 5. put the layer in the image
# 6. repack the image
buildImage = args@{
# Image name.
name,
# Image tag.
tag ? "latest",
# Parent image, to append to.
fromImage ? null,
# Name of the parent image; will be read from the image otherwise.
fromImageName ? null,
# Tag of the parent image; will be read from the image otherwise.
fromImageTag ? null,
# Files to put on the image (a nix store path or list of paths).
contents ? null,
# Docker config; e.g. what command to run on the container.
config ? null,
# Optional bash script to run on the files prior to fixturizing the layer.
extraCommands ? "", uid ? 0, gid ? 0,
# Optional bash script to run as root on the image when provisioning.
runAsRoot ? null,
# Size of the virtual machine disk to provision when building the image.
diskSize ? 1024,
# Time of creation of the image.
created ? "1970-01-01T00:00:01Z",
}:
let
baseName = baseNameOf name;
# Create a JSON blob of the configuration. Set the date to unix zero.
baseJson = writeText "${baseName}-config.json" (builtins.toJSON {
inherit created config;
architecture = "amd64";
os = "linux";
});
layer =
if runAsRoot == null
then mkPureLayer {
name = baseName;
inherit baseJson contents extraCommands uid gid;
} else mkRootLayer {
name = baseName;
inherit baseJson fromImage fromImageName fromImageTag
contents runAsRoot diskSize extraCommands;
};
result = runCommand "docker-image-${baseName}.tar.gz" {
buildInputs = [ jshon pigz coreutils findutils jq ];
# Image name and tag must be lowercase
imageName = lib.toLower name;
imageTag = lib.toLower tag;
inherit fromImage baseJson;
layerClosure = writeReferencesToFile layer;
passthru.buildArgs = args;
passthru.layer = layer;
} ''
# Print tar contents:
# 1: Interpreted as relative to the root directory
# 2: With no trailing slashes on directories
# This is useful for ensuring that the output matches the
# values generated by the "find" command
ls_tar() {
for f in $(tar -tf $1 | xargs realpath -ms --relative-to=.); do
if [[ "$f" != "." ]]; then
echo "/$f"
fi
done
}
mkdir image
touch baseFiles
if [[ -n "$fromImage" ]]; then
echo "Unpacking base image..."
tar -C image -xpf "$fromImage"
# Do not import the base image configuration and manifest
chmod a+w image image/*.json
rm -f image/*.json
if [[ -z "$fromImageName" ]]; then
fromImageName=$(jshon -k < image/repositories|head -n1)
fi
if [[ -z "$fromImageTag" ]]; then
fromImageTag=$(jshon -e $fromImageName -k \
< image/repositories|head -n1)
fi
parentID=$(jshon -e $fromImageName -e $fromImageTag -u \
< image/repositories)
for l in image/*/layer.tar; do
ls_tar $l >> baseFiles
done
fi
chmod -R ug+rw image
mkdir temp
cp ${layer}/* temp/
chmod ug+w temp/*
echo "$(dirname ${storeDir})" >> layerFiles
echo '${storeDir}' >> layerFiles
for dep in $(cat $layerClosure); do
find $dep >> layerFiles
done
echo "Adding layer..."
# Record the contents of the tarball with ls_tar.
ls_tar temp/layer.tar >> baseFiles
# Get the files in the new layer which were *not* present in
# the old layer, and record them as newFiles.
comm <(sort -n baseFiles|uniq) \
<(sort -n layerFiles|uniq|grep -v ${layer}) -1 -3 > newFiles
# Append the new files to the layer.
tar -rpf temp/layer.tar --mtime="@$SOURCE_DATE_EPOCH" \
--owner=0 --group=0 --no-recursion --files-from newFiles
echo "Adding meta..."
# If we have a parentID, add it to the json metadata.
if [[ -n "$parentID" ]]; then
cat temp/json | jshon -s "$parentID" -i parent > tmpjson
mv tmpjson temp/json
fi
# Take the sha256 sum of the generated json and use it as the layer ID.
# Compute the size and add it to the json under the 'Size' field.
layerID=$(sha256sum temp/json|cut -d ' ' -f 1)
size=$(stat --printf="%s" temp/layer.tar)
cat temp/json | jshon -s "$layerID" -i id -n $size -i Size > tmpjson
mv tmpjson temp/json
# Use the temp folder we've been working on to create a new image.
mv temp image/$layerID
# Create image configuration file (used by registry v2) by using
# the configuration of the last layer
SHA_ARRAY=$(find ./ -name layer.tar | xargs sha256sum | cut -d" " -f1 | xargs -I{} echo -n '"sha256:{}" ' | sed 's/" "/","/g' | awk '{ print "["$1"]" }')
jq ". + {\"rootfs\": {\"diff_ids\": $SHA_ARRAY, \"type\": \"layers\"}}" image/$layerID/json > config.json
CONFIG_SHA=$(sha256sum config.json | cut -d ' ' -f1)
mv config.json image/$CONFIG_SHA.json
# Create image manifest
LAYER_PATHS=$(find image/ -name layer.tar -printf '"%P" ' | sed 's/" "/","/g')
jq -n "[{\"Config\":\"$CONFIG_SHA.json\",\"RepoTags\":[\"$imageName:$imageTag\"],\"Layers\":[$LAYER_PATHS]}]" > image/manifest.json
# Store the json under the name image/repositories.
jshon -n object \
-n object -s "$layerID" -i "$imageTag" \
-i "$imageName" > image/repositories
# Make the image read-only.
chmod -R a-w image
echo "Cooking the image..."
tar -C image --mtime="@$SOURCE_DATE_EPOCH" --owner=0 --group=0 --xform s:'./':: -c . | pigz -nT > $out
echo "Finished."
'';
in
result;
}