4fe9006190
Create a many-layered Docker Image.
Implements much less than buildImage:
- Doesn't support specific uids/gids
- Doesn't support runninng commands after building
- Doesn't require qemu
- Doesn't create mutable copies of the files in the path
- Doesn't support parent images
If you want those feature, I recommend using buildLayeredImage as an
input to buildImage.
Notably, it does support:
- Caching low level, common paths based on a graph traversial
algorithm, see referencesByPopularity in
0a80233487993256e811f566b1c80a40394c03d6
- Configurable number of layers. If you're not using AUFS or not
extending the image, you can specify a larger number of layers at
build time:
pkgs.dockerTools.buildLayeredImage {
name = "hello";
maxLayers = 128;
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
- Parallelized creation of the layers, improving build speed.
- The contents of the image includes the closure of the configuration,
so you don't have to specify paths in contents and config.
With buildImage, paths referred to by the config were not included
automatically in the image. Thus, if you wanted to call Git, you
had to specify it twice:
pkgs.dockerTools.buildImage {
name = "hello";
contents = [ pkgs.gitFull ];
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
buildLayeredImage on the other hand includes the runtime closure of
the config when calculating the contents of the image:
pkgs.dockerTools.buildImage {
name = "hello";
config.Cmd = [ "${pkgs.gitFull}/bin/git" ];
};
Minor Problems
- If any of the store paths change, every layer will be rebuilt in
the nix-build. However, beacuse the layers are bit-for-bit
reproducable, when these images are loaded in to Docker they will
match existing layers and not be imported or uploaded twice.
Common Questions
- Aren't Docker layers ordered?
No. People who have used a Dockerfile before assume Docker's
Layers are inherently ordered. However, this is not true -- Docker
layers are content-addressable and are not explicitly layered until
they are composed in to an Image.
- What happens if I have more than maxLayers of store paths?
The first (maxLayers-2) most "popular" paths will have their own
individual layers, then layer #(maxLayers-1) will contain all the
remaining "unpopular" paths, and finally layer #(maxLayers) will
contain the Image configuration.
825 lines
28 KiB
Nix
825 lines
28 KiB
Nix
{
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symlinkJoin,
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coreutils,
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docker,
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e2fsprogs,
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findutils,
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go,
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jshon,
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jq,
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lib,
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pkgs,
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pigz,
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nixUnstable,
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perl,
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runCommand,
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rsync,
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shadow,
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stdenv,
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storeDir ? builtins.storeDir,
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utillinux,
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vmTools,
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writeReferencesToFile,
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referencesByPopularity,
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writeScript,
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writeText,
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}:
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# WARNING: this API is unstable and may be subject to backwards-incompatible changes in the future.
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rec {
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examples = import ./examples.nix {
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inherit pkgs buildImage pullImage shadowSetup buildImageWithNixDb;
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};
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pullImage = let
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fixName = name: builtins.replaceStrings ["/" ":"] ["-" "-"] name;
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in
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{ imageName
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# To find the digest of an image, you can use skopeo:
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# see doc/functions.xml
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, imageDigest
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, sha256
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, os ? "linux"
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, arch ? "amd64"
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# This used to set a tag to the pulled image
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, finalImageTag ? "latest"
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, name ? fixName "docker-image-${imageName}-${finalImageTag}.tar"
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}:
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runCommand name {
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inherit imageName imageDigest;
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imageTag = finalImageTag;
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impureEnvVars = pkgs.stdenv.lib.fetchers.proxyImpureEnvVars;
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outputHashMode = "flat";
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outputHashAlgo = "sha256";
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outputHash = sha256;
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nativeBuildInputs = lib.singleton (pkgs.skopeo);
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SSL_CERT_FILE = "${pkgs.cacert.out}/etc/ssl/certs/ca-bundle.crt";
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sourceURL = "docker://${imageName}@${imageDigest}";
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destNameTag = "${imageName}:${finalImageTag}";
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} ''
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skopeo --override-os ${os} --override-arch ${arch} copy "$sourceURL" "docker-archive://$out:$destNameTag"
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'';
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# We need to sum layer.tar, not a directory, hence tarsum instead of nix-hash.
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# And we cannot untar it, because then we cannot preserve permissions ecc.
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tarsum = runCommand "tarsum" {
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buildInputs = [ go ];
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} ''
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mkdir tarsum
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cd tarsum
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cp ${./tarsum.go} tarsum.go
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export GOPATH=$(pwd)
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mkdir -p src/github.com/docker/docker/pkg
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ln -sT ${docker.src}/components/engine/pkg/tarsum src/github.com/docker/docker/pkg/tarsum
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go build
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mkdir -p $out/bin
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cp tarsum $out/bin/
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'';
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# buildEnv creates symlinks to dirs, which is hard to edit inside the overlay VM
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mergeDrvs = {
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derivations,
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onlyDeps ? false
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}:
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runCommand "merge-drvs" {
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inherit derivations onlyDeps;
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} ''
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if [[ -n "$onlyDeps" ]]; then
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echo $derivations > $out
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exit 0
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fi
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mkdir $out
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for derivation in $derivations; do
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echo "Merging $derivation..."
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if [[ -d "$derivation" ]]; then
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# If it's a directory, copy all of its contents into $out.
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cp -drf --preserve=mode -f $derivation/* $out/
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else
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# Otherwise treat the derivation as a tarball and extract it
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# into $out.
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tar -C $out -xpf $drv || true
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fi
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done
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'';
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# Helper for setting up the base files for managing users and
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# groups, only if such files don't exist already. It is suitable for
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# being used in a runAsRoot script.
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shadowSetup = ''
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export PATH=${shadow}/bin:$PATH
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mkdir -p /etc/pam.d
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if [[ ! -f /etc/passwd ]]; then
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echo "root:x:0:0::/root:${stdenv.shell}" > /etc/passwd
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echo "root:!x:::::::" > /etc/shadow
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fi
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if [[ ! -f /etc/group ]]; then
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echo "root:x:0:" > /etc/group
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echo "root:x::" > /etc/gshadow
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fi
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if [[ ! -f /etc/pam.d/other ]]; then
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cat > /etc/pam.d/other <<EOF
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account sufficient pam_unix.so
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auth sufficient pam_rootok.so
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password requisite pam_unix.so nullok sha512
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session required pam_unix.so
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EOF
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fi
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if [[ ! -f /etc/login.defs ]]; then
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touch /etc/login.defs
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fi
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'';
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# Run commands in a virtual machine.
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runWithOverlay = {
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name,
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fromImage ? null,
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fromImageName ? null,
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fromImageTag ? null,
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diskSize ? 1024,
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preMount ? "",
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postMount ? "",
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postUmount ? ""
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}:
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vmTools.runInLinuxVM (
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runCommand name {
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preVM = vmTools.createEmptyImage {
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size = diskSize;
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fullName = "docker-run-disk";
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};
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inherit fromImage fromImageName fromImageTag;
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buildInputs = [ utillinux e2fsprogs jshon rsync ];
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} ''
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rm -rf $out
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mkdir disk
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mkfs /dev/${vmTools.hd}
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mount /dev/${vmTools.hd} disk
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cd disk
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if [[ -n "$fromImage" ]]; then
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echo "Unpacking base image..."
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mkdir image
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tar -C image -xpf "$fromImage"
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# If the image name isn't set, read it from the image repository json.
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if [[ -z "$fromImageName" ]]; then
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fromImageName=$(jshon -k < image/repositories | head -n 1)
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echo "From-image name wasn't set. Read $fromImageName."
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fi
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# If the tag isn't set, use the name as an index into the json
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# and read the first key found.
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if [[ -z "$fromImageTag" ]]; then
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fromImageTag=$(jshon -e $fromImageName -k < image/repositories \
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| head -n1)
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echo "From-image tag wasn't set. Read $fromImageTag."
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fi
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# Use the name and tag to get the parent ID field.
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parentID=$(jshon -e $fromImageName -e $fromImageTag -u \
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< image/repositories)
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fi
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# Unpack all of the parent layers into the image.
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lowerdir=""
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while [[ -n "$parentID" ]]; do
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echo "Unpacking layer $parentID"
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mkdir -p image/$parentID/layer
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tar -C image/$parentID/layer -xpf image/$parentID/layer.tar
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rm image/$parentID/layer.tar
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find image/$parentID/layer -name ".wh.*" -exec bash -c 'name="$(basename {}|sed "s/^.wh.//")"; mknod "$(dirname {})/$name" c 0 0; rm {}' \;
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# Get the next lower directory and continue the loop.
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lowerdir=$lowerdir''${lowerdir:+:}image/$parentID/layer
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parentID=$(cat image/$parentID/json \
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| (jshon -e parent -u 2>/dev/null || true))
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done
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mkdir work
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mkdir layer
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mkdir mnt
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${lib.optionalString (preMount != "") ''
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# Execute pre-mount steps
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echo "Executing pre-mount steps..."
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${preMount}
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''}
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if [ -n "$lowerdir" ]; then
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mount -t overlay overlay -olowerdir=$lowerdir,workdir=work,upperdir=layer mnt
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else
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mount --bind layer mnt
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fi
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${lib.optionalString (postMount != "") ''
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# Execute post-mount steps
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echo "Executing post-mount steps..."
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${postMount}
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''}
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umount mnt
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(
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cd layer
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cmd='name="$(basename {})"; touch "$(dirname {})/.wh.$name"; rm "{}"'
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find . -type c -exec bash -c "$cmd" \;
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)
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${postUmount}
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'');
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exportImage = { name ? fromImage.name, fromImage, fromImageName ? null, fromImageTag ? null, diskSize ? 1024 }:
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runWithOverlay {
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inherit name fromImage fromImageName fromImageTag diskSize;
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postMount = ''
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echo "Packing raw image..."
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tar -C mnt --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf $out .
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'';
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};
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# Create an executable shell script which has the coreutils in its
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# PATH. Since root scripts are executed in a blank environment, even
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# things like `ls` or `echo` will be missing.
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shellScript = name: text:
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writeScript name ''
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#!${stdenv.shell}
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set -e
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export PATH=${coreutils}/bin:/bin
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${text}
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'';
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nixRegistration = contents: runCommand "nix-registration" {
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buildInputs = [ nixUnstable perl ];
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# For obtaining the closure of `contents'.
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exportReferencesGraph =
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let contentsList = if builtins.isList contents then contents else [ contents ];
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in map (x: [("closure-" + baseNameOf x) x]) contentsList;
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}
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''
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mkdir $out
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printRegistration=1 perl ${pkgs.pathsFromGraph} closure-* > $out/db.dump
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perl ${pkgs.pathsFromGraph} closure-* > $out/storePaths
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'';
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# Create $maxLayers worth of Docker Layers, one layer per store path
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# unless there are more paths than $maxLayers. In that case, create
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# $maxLayers-1 for the most popular layers, and smush the remainaing
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# store paths in to one final layer.
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mkManyPureLayers = {
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name,
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# Files to add to the layer.
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closure,
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configJson,
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# Docker has a 42-layer maximum, we pick 24 to ensure there is plenty
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# of room for extension
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maxLayers ? 24
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}:
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runCommand "${name}-granular-docker-layers" {
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inherit maxLayers;
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paths = referencesByPopularity closure;
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buildInputs = [ jshon rsync tarsum ];
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enableParallelBuilding = true;
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}
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''
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# Delete impurities for store path layers, so they don't get
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# shared and taint other projects.
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cat ${configJson} \
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| jshon -d config \
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| jshon -s "1970-01-01T00:00:01Z" -i created > generic.json
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# WARNING!
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# The following code is fiddly w.r.t. ensuring every layer is
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# created, and that no paths are missed. If you change the
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# following head and tail call lines, double-check that your
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# code behaves properly when the number of layers equals:
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# maxLayers-1, maxLayers, and maxLayers+1
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head -n $((maxLayers - 1)) $paths | cat -n | xargs -P$NIX_BUILD_CORES -n2 ${./store-path-to-layer.sh}
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if [ $(cat $paths | wc -l) -ge $maxLayers ]; then
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tail -n+$maxLayers $paths | xargs ${./store-path-to-layer.sh} $maxLayers
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fi
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echo "Finished building layer '$name'"
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mv ./layers $out
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'';
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# Create a "Customisation" layer which adds symlinks at the root of
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# the image to the root paths of the closure. Also add the config
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# data like what command to run and the environment to run it in.
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mkCustomisationLayer = {
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name,
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# Files to add to the layer.
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contents,
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baseJson,
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uid ? 0, gid ? 0,
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}:
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runCommand "${name}-customisation-layer" {
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buildInputs = [ jshon rsync tarsum ];
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}
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''
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cp -r ${contents}/ ./layer
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# Tar up the layer and throw it into 'layer.tar'.
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echo "Packing layer..."
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mkdir $out
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tar -C layer --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
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# Compute a checksum of the tarball.
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echo "Computing layer checksum..."
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tarhash=$(tarsum < $out/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 ${baseJson} | jshon -s "$tarhash" -i checksum > $out/json
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# Indicate to docker that we're using schema version 1.0.
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echo -n "1.0" > $out/VERSION
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'';
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# Create a "layer" (set of files).
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mkPureLayer = {
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# Name of the layer
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name,
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# JSON containing configuration and metadata for this layer.
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baseJson,
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# Files to add to the layer.
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contents ? null,
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# When copying the contents into the image, preserve symlinks to
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# directories (see `rsync -K`). Otherwise, transform those symlinks
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# into directories.
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keepContentsDirlinks ? false,
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# Additional commands to run on the layer before it is tar'd up.
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extraCommands ? "", uid ? 0, gid ? 0
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}:
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runCommand "docker-layer-${name}" {
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inherit baseJson contents extraCommands;
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buildInputs = [ jshon rsync tarsum ];
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}
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''
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mkdir layer
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if [[ -n "$contents" ]]; then
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echo "Adding contents..."
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for item in $contents; do
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echo "Adding $item"
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rsync -a${if keepContentsDirlinks then "K" else "k"} --chown=0:0 $item/ layer/
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done
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else
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echo "No contents to add to layer."
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fi
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chmod ug+w layer
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if [[ -n $extraCommands ]]; then
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(cd layer; eval "$extraCommands")
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fi
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# Tar up the layer and throw it into 'layer.tar'.
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echo "Packing layer..."
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mkdir $out
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tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
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# Compute a checksum of the tarball.
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echo "Computing layer checksum..."
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tarhash=$(tarsum < $out/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 ${baseJson} | jshon -s "$tarhash" -i checksum > $out/json
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# Indicate to docker that we're using schema version 1.0.
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echo -n "1.0" > $out/VERSION
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echo "Finished building layer '${name}'"
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'';
|
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# Make a "root" layer; required if we need to execute commands as a
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# privileged user on the image. The commands themselves will be
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# performed in a virtual machine sandbox.
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mkRootLayer = {
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# Name of the image.
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name,
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# Script to run as root. Bash.
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runAsRoot,
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# Files to add to the layer. If null, an empty layer will be created.
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contents ? null,
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# When copying the contents into the image, preserve symlinks to
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# directories (see `rsync -K`). Otherwise, transform those symlinks
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# into directories.
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keepContentsDirlinks ? false,
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# JSON containing configuration and metadata for this layer.
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baseJson,
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# Existing image onto which to append the new layer.
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fromImage ? null,
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# Name of the image we're appending onto.
|
|
fromImageName ? null,
|
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# Tag of the image we're appending onto.
|
|
fromImageTag ? null,
|
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# 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 ? ""
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}:
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# Generate an executable script from the `runAsRoot` text.
|
|
let
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runAsRootScript = shellScript "run-as-root.sh" runAsRoot;
|
|
extraCommandsScript = shellScript "extra-commands.sh" extraCommands;
|
|
in runWithOverlay {
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name = "docker-layer-${name}";
|
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|
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inherit fromImage fromImageName fromImageTag diskSize;
|
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|
|
preMount = lib.optionalString (contents != null && contents != []) ''
|
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echo "Adding contents..."
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|
for item in ${toString contents}; do
|
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echo "Adding $item..."
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rsync -a${if keepContentsDirlinks then "K" else "k"} --chown=0:0 $item/ layer/
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done
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|
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chmod ug+w layer
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'';
|
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|
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postMount = ''
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mkdir -p mnt/{dev,proc,sys} mnt${storeDir}
|
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|
|
# Mount /dev, /sys and the nix store as shared folders.
|
|
mount --rbind /dev mnt/dev
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mount --rbind /sys mnt/sys
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mount --rbind ${storeDir} mnt${storeDir}
|
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|
|
# Execute the run as root script. See 'man unshare' for
|
|
# details on what's going on here; basically this command
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|
# means that the runAsRootScript will be executed in a nearly
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# completely isolated environment.
|
|
unshare -imnpuf --mount-proc chroot mnt ${runAsRootScript}
|
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|
|
# Unmount directories and remove them.
|
|
umount -R mnt/dev mnt/sys mnt${storeDir}
|
|
rmdir --ignore-fail-on-non-empty \
|
|
mnt/dev mnt/proc mnt/sys mnt${storeDir} \
|
|
mnt$(dirname ${storeDir})
|
|
'';
|
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|
|
postUmount = ''
|
|
(cd layer; ${extraCommandsScript})
|
|
|
|
echo "Packing layer..."
|
|
mkdir $out
|
|
tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" -cf $out/layer.tar .
|
|
|
|
# Compute the tar checksum and add it to the output json.
|
|
echo "Computing checksum..."
|
|
tarhash=$(${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" > $out/VERSION
|
|
|
|
echo "Finished building layer '${name}'"
|
|
'';
|
|
};
|
|
|
|
buildLayeredImage = {
|
|
# Image Name
|
|
name,
|
|
# Image tag, the Nix's output hash will be used if null
|
|
tag ? null,
|
|
# Files to put on the image (a nix store path or list of paths).
|
|
contents ? [],
|
|
# Docker config; e.g. what command to run on the container.
|
|
config ? {},
|
|
# Time of creation of the image. Passing "now" will make the
|
|
# created date be the time of building.
|
|
created ? "1970-01-01T00:00:01Z",
|
|
# Docker's lowest maximum layer limit is 42-layers for an old
|
|
# version of the AUFS graph driver. We pick 24 to ensure there is
|
|
# plenty of room for extension. I believe the actual maximum is
|
|
# 128.
|
|
maxLayers ? 24
|
|
}:
|
|
let
|
|
uid = 0;
|
|
gid = 0;
|
|
baseName = baseNameOf name;
|
|
contentsEnv = symlinkJoin { name = "bulk-layers"; paths = (if builtins.isList contents then contents else [ contents ]); };
|
|
|
|
configJson = let
|
|
pure = writeText "${baseName}-config.json" (builtins.toJSON {
|
|
inherit created config;
|
|
architecture = "amd64";
|
|
os = "linux";
|
|
});
|
|
impure = runCommand "${baseName}-standard-dynamic-date.json"
|
|
{ buildInputs = [ jq ]; }
|
|
''
|
|
jq ".created = \"$(TZ=utc date --iso-8601="seconds")\"" ${pure} > $out
|
|
'';
|
|
in if created == "now" then impure else pure;
|
|
|
|
bulkLayers = mkManyPureLayers {
|
|
name = baseName;
|
|
closure = writeText "closure" "${contentsEnv} ${configJson}";
|
|
# One layer will be taken up by the customisationLayer, so
|
|
# take up one less.
|
|
maxLayers = maxLayers - 1;
|
|
inherit configJson;
|
|
};
|
|
customisationLayer = mkCustomisationLayer {
|
|
name = baseName;
|
|
contents = contentsEnv;
|
|
baseJson = configJson;
|
|
inherit uid gid;
|
|
};
|
|
result = runCommand "docker-image-${baseName}.tar.gz" {
|
|
buildInputs = [ jshon pigz coreutils findutils jq ];
|
|
# Image name and tag must be lowercase
|
|
imageName = lib.toLower name;
|
|
imageTag = if tag == null then "" else lib.toLower tag;
|
|
baseJson = configJson;
|
|
} ''
|
|
${lib.optionalString (tag == null) ''
|
|
outName="$(basename "$out")"
|
|
outHash=$(echo "$outName" | cut -d - -f 1)
|
|
|
|
imageTag=$outHash
|
|
''}
|
|
|
|
find ${bulkLayers} -mindepth 1 -maxdepth 1 | sort -t/ -k5 -n > layer-list
|
|
echo ${customisationLayer} >> layer-list
|
|
|
|
mkdir image
|
|
imageJson=$(cat ${configJson} | jq ". + {\"rootfs\": {\"diff_ids\": [], \"type\": \"layers\"}}")
|
|
manifestJson=$(jq -n "[{\"RepoTags\":[\"$imageName:$imageTag\"]}]")
|
|
for layer in $(cat layer-list); do
|
|
layerChecksum=$(sha256sum $layer/layer.tar | cut -d ' ' -f1)
|
|
layerID=$(sha256sum "$layer/json" | cut -d ' ' -f 1)
|
|
ln -s "$layer" "./image/$layerID"
|
|
|
|
manifestJson=$(echo "$manifestJson" | jq ".[0].Layers |= [\"$layerID/layer.tar\"] + .")
|
|
imageJson=$(echo "$imageJson" | jq ".history |= [{\"created\": \"$(jq -r .created ${configJson})\"}] + .")
|
|
imageJson=$(echo "$imageJson" | jq ".rootfs.diff_ids |= [\"sha256:$layerChecksum\"] + .")
|
|
done
|
|
imageJsonChecksum=$(echo "$imageJson" | sha256sum | cut -d ' ' -f1)
|
|
echo "$imageJson" > "image/$imageJsonChecksum.json"
|
|
manifestJson=$(echo "$manifestJson" | jq ".[0].Config = \"$imageJsonChecksum.json\"")
|
|
echo "$manifestJson" > image/manifest.json
|
|
|
|
jshon -n object \
|
|
-n object -s "$layerID" -i "$imageTag" \
|
|
-i "$imageName" > image/repositories
|
|
|
|
echo "Cooking the image..."
|
|
tar -C image --dereference --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=0 --group=0 --mode=a-w --xform s:'^./':: -c . | pigz -nT > $out
|
|
|
|
echo "Finished."
|
|
'';
|
|
|
|
in
|
|
result;
|
|
|
|
# 1. extract the base image
|
|
# 2. create the layer
|
|
# 3. add layer deps to the layer itself, diffing with the base image
|
|
# 4. compute the layer id
|
|
# 5. put the layer in the image
|
|
# 6. repack the image
|
|
buildImage = args@{
|
|
# Image name.
|
|
name,
|
|
# Image tag, when null then the nix output hash will be used.
|
|
tag ? null,
|
|
# Parent image, to append to.
|
|
fromImage ? null,
|
|
# Name of the parent image; will be read from the image otherwise.
|
|
fromImageName ? null,
|
|
# Tag of the parent image; will be read from the image otherwise.
|
|
fromImageTag ? null,
|
|
# Files to put on the image (a nix store path or list of paths).
|
|
contents ? null,
|
|
# When copying the contents into the image, preserve symlinks to
|
|
# directories (see `rsync -K`). Otherwise, transform those symlinks
|
|
# into directories.
|
|
keepContentsDirlinks ? false,
|
|
# Docker config; e.g. what command to run on the container.
|
|
config ? null,
|
|
# Optional bash script to run on the files prior to fixturizing the layer.
|
|
extraCommands ? "", uid ? 0, gid ? 0,
|
|
# Optional bash script to run as root on the image when provisioning.
|
|
runAsRoot ? null,
|
|
# Size of the virtual machine disk to provision when building the image.
|
|
diskSize ? 1024,
|
|
# Time of creation of the image.
|
|
created ? "1970-01-01T00:00:01Z",
|
|
}:
|
|
|
|
let
|
|
baseName = baseNameOf name;
|
|
|
|
# Create a JSON blob of the configuration. Set the date to unix zero.
|
|
baseJson = let
|
|
pure = writeText "${baseName}-config.json" (builtins.toJSON {
|
|
inherit created config;
|
|
architecture = "amd64";
|
|
os = "linux";
|
|
});
|
|
impure = runCommand "${baseName}-config.json"
|
|
{ buildInputs = [ jq ]; }
|
|
''
|
|
jq ".created = \"$(TZ=utc date --iso-8601="seconds")\"" ${pure} > $out
|
|
'';
|
|
in if created == "now" then impure else pure;
|
|
|
|
layer =
|
|
if runAsRoot == null
|
|
then mkPureLayer {
|
|
name = baseName;
|
|
inherit baseJson contents keepContentsDirlinks extraCommands uid gid;
|
|
} else mkRootLayer {
|
|
name = baseName;
|
|
inherit baseJson fromImage fromImageName fromImageTag
|
|
contents keepContentsDirlinks runAsRoot diskSize
|
|
extraCommands;
|
|
};
|
|
result = runCommand "docker-image-${baseName}.tar.gz" {
|
|
buildInputs = [ jshon pigz coreutils findutils jq ];
|
|
# Image name and tag must be lowercase
|
|
imageName = lib.toLower name;
|
|
imageTag = if tag == null then "" else lib.toLower tag;
|
|
inherit fromImage baseJson;
|
|
layerClosure = writeReferencesToFile layer;
|
|
passthru.buildArgs = args;
|
|
passthru.layer = layer;
|
|
} ''
|
|
${lib.optionalString (tag == null) ''
|
|
outName="$(basename "$out")"
|
|
outHash=$(echo "$outName" | cut -d - -f 1)
|
|
|
|
imageTag=$outHash
|
|
''}
|
|
|
|
# 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/*
|
|
|
|
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
|
|
|
|
# Append nix/store directory to the layer so that when the layer is loaded in the
|
|
# image /nix/store has read permissions for non-root users.
|
|
# nix/store is added only if the layer has /nix/store paths in it.
|
|
if [ $(wc -l < $layerClosure) -gt 1 ] && [ $(grep -c -e "^/nix/store$" baseFiles) -eq 0 ]; then
|
|
mkdir -p nix/store
|
|
chmod -R 555 nix
|
|
echo "./nix" >> layerFiles
|
|
echo "./nix/store" >> layerFiles
|
|
fi
|
|
|
|
# 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 ${layer}) -1 -3 > newFiles
|
|
# Append the new files to the layer.
|
|
tar -rpf temp/layer.tar --hard-dereference --sort=name --mtime="@$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 json and image manifest
|
|
imageJson=$(cat ${baseJson} | jq ". + {\"rootfs\": {\"diff_ids\": [], \"type\": \"layers\"}}")
|
|
manifestJson=$(jq -n "[{\"RepoTags\":[\"$imageName:$imageTag\"]}]")
|
|
currentID=$layerID
|
|
while [[ -n "$currentID" ]]; do
|
|
layerChecksum=$(sha256sum image/$currentID/layer.tar | cut -d ' ' -f1)
|
|
imageJson=$(echo "$imageJson" | jq ".history |= [{\"created\": \"$(jq -r .created ${baseJson})\"}] + .")
|
|
imageJson=$(echo "$imageJson" | jq ".rootfs.diff_ids |= [\"sha256:$layerChecksum\"] + .")
|
|
manifestJson=$(echo "$manifestJson" | jq ".[0].Layers |= [\"$currentID/layer.tar\"] + .")
|
|
|
|
currentID=$(cat image/$currentID/json | (jshon -e parent -u 2>/dev/null || true))
|
|
done
|
|
|
|
imageJsonChecksum=$(echo "$imageJson" | sha256sum | cut -d ' ' -f1)
|
|
echo "$imageJson" > "image/$imageJsonChecksum.json"
|
|
manifestJson=$(echo "$manifestJson" | jq ".[0].Config = \"$imageJsonChecksum.json\"")
|
|
echo "$manifestJson" > image/manifest.json
|
|
|
|
# Store the json under the name image/repositories.
|
|
jshon -n object \
|
|
-n object -s "$layerID" -i "$imageTag" \
|
|
-i "$imageName" > image/repositories
|
|
|
|
# Make the image read-only.
|
|
chmod -R a-w image
|
|
|
|
echo "Cooking the image..."
|
|
tar -C image --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=0 --group=0 --xform s:'^./':: -c . | pigz -nT > $out
|
|
|
|
echo "Finished."
|
|
'';
|
|
|
|
in
|
|
result;
|
|
|
|
# Build an image and populate its nix database with the provided
|
|
# contents. The main purpose is to be able to use nix commands in
|
|
# the container.
|
|
# Be careful since this doesn't work well with multilayer.
|
|
buildImageWithNixDb = args@{ contents ? null, extraCommands ? "", ... }:
|
|
buildImage (args // {
|
|
extraCommands = ''
|
|
echo "Generating the nix database..."
|
|
echo "Warning: only the database of the deepest Nix layer is loaded."
|
|
echo " If you want to use nix commands in the container, it would"
|
|
echo " be better to only have one layer that contains a nix store."
|
|
# This requires Nix 1.12 or higher
|
|
export NIX_REMOTE=local?root=$PWD
|
|
${nixUnstable}/bin/nix-store --load-db < ${nixRegistration contents}/db.dump
|
|
|
|
# We fill the store in order to run the 'verify' command that
|
|
# generates hash and size of output paths.
|
|
# Note when Nix 1.12 is be the stable one, the database dump
|
|
# generated by the exportReferencesGraph function will
|
|
# contains sha and size. See
|
|
# https://github.com/NixOS/nix/commit/c2b0d8749f7e77afc1c4b3e8dd36b7ee9720af4a
|
|
storePaths=$(cat ${nixRegistration contents}/storePaths)
|
|
echo "Copying everything to /nix/store (will take a while)..."
|
|
cp -prd $storePaths nix/store/
|
|
${nixUnstable}/bin/nix-store --verify --check-contents
|
|
|
|
mkdir -p nix/var/nix/gcroots/docker/
|
|
for i in ${lib.concatStringsSep " " contents}; do
|
|
ln -s $i nix/var/nix/gcroots/docker/$(basename $i)
|
|
done;
|
|
'' + extraCommands;
|
|
});
|
|
}
|