lix/docker.nix
Jade Lovelace 9bb7fb8f69 Rewrite docker to be sensible and smaller
I have checked the image can build things and inspected `diff -ru`
compared to the old image. As far as I can tell it is more or less
the same besides the later git change.

Layers are now 65MB or less, and we aren't against the maxLayers limit
for the broken automatic layering to do anything but shove one store
path in a layer (which is good behaviour, actually).

This uses nix2container which streams images, so the build time is much
shorter.

I have also taken the opportunity to, in addition to fixing the 400MB
single layer (terrible, and what motivated this in the first place),
delete about 200MB of closure size inflicted by git vs gitMinimal
causing both perl and python to get into closure.

People mostly use this thing for CI, so I don't really think you need
advanced git operations, and large git can be added at the user side if
really motivated.

With love for whichever container developer somewhat ironically assumed
that one would not run skopeo in a minimal container that doesn't have a
/var/tmp.

Fixes: https://git.lix.systems/lix-project/lix/issues/378

Change-Id: Icc3aa20e64446276716fbbb87535fd5b50628010
2024-06-09 20:33:24 -07:00

390 lines
11 KiB
Nix

{
pkgs ? import <nixpkgs> { },
nix2container,
lib ? pkgs.lib,
name ? "lix",
tag ? "latest",
bundleNixpkgs ? true,
channelName ? "nixpkgs",
channelURL ? "https://nixos.org/channels/nixpkgs-unstable",
extraPkgs ? [ ],
maxLayers ? 100,
nixConf ? { },
flake-registry ? null,
}:
let
layerContents = with pkgs; [
# pulls in glibc and openssl, about 60MB
{ contents = [ coreutils-full ]; }
# some stuff that is low in the closure graph and small ish, mostly to make
# incremental lix updates cheaper
{
contents = [
curl
libxml2
sqlite
];
}
# 50MB of git
{ contents = [ gitMinimal ]; }
# 144MB of nixpkgs
{
contents = [ channel ];
inProfile = false;
}
];
# These packages are left to be auto layered by nix2container, since it is
# less critical that they get layered sensibly and they tend to not be deps
# of anything in particular
autoLayered = with pkgs; [
bashInteractive
gnutar
gzip
gnugrep
which
less
wget
man
cacert.out
findutils
iana-etc
openssh
nix
];
defaultPkgs =
lib.lists.flatten (
map (x: if !(x ? inProfile) || x.inProfile then x.contents else [ ]) layerContents
)
++ autoLayered
++ extraPkgs;
users =
{
root = {
uid = 0;
shell = "${pkgs.bashInteractive}/bin/bash";
home = "/root";
gid = 0;
groups = [ "root" ];
description = "System administrator";
};
nobody = {
uid = 65534;
shell = "${pkgs.shadow}/bin/nologin";
home = "/var/empty";
gid = 65534;
groups = [ "nobody" ];
description = "Unprivileged account (don't use!)";
};
}
// lib.listToAttrs (
map (n: {
name = "nixbld${toString n}";
value = {
uid = 30000 + n;
gid = 30000;
groups = [ "nixbld" ];
description = "Nix build user ${toString n}";
};
}) (lib.lists.range 1 32)
);
groups = {
root.gid = 0;
nixbld.gid = 30000;
nobody.gid = 65534;
};
userToPasswd = (
k:
{
uid,
gid ? 65534,
home ? "/var/empty",
description ? "",
shell ? "/bin/false",
groups ? [ ],
}:
"${k}:x:${toString uid}:${toString gid}:${description}:${home}:${shell}"
);
passwdContents = (lib.concatStringsSep "\n" (lib.attrValues (lib.mapAttrs userToPasswd users)));
userToShadow = k: { ... }: "${k}:!:1::::::";
shadowContents = (lib.concatStringsSep "\n" (lib.attrValues (lib.mapAttrs userToShadow users)));
# Map groups to members
# {
# group = [ "user1" "user2" ];
# }
groupMemberMap = (
let
# Create a flat list of user/group mappings
mappings = (
builtins.foldl' (
acc: user:
let
groups = users.${user}.groups or [ ];
in
acc ++ map (group: { inherit user group; }) groups
) [ ] (lib.attrNames users)
);
in
(builtins.foldl' (
acc: v: acc // { ${v.group} = acc.${v.group} or [ ] ++ [ v.user ]; }
) { } mappings)
);
groupToGroup =
k:
{ gid }:
let
members = groupMemberMap.${k} or [ ];
in
"${k}:x:${toString gid}:${lib.concatStringsSep "," members}";
groupContents = (lib.concatStringsSep "\n" (lib.attrValues (lib.mapAttrs groupToGroup groups)));
defaultNixConf = {
sandbox = "false";
build-users-group = "nixbld";
trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
};
nixConfContents =
(lib.concatStringsSep "\n" (
lib.mapAttrsFlatten (
n: v:
let
vStr = if builtins.isList v then lib.concatStringsSep " " v else v;
in
"${n} = ${vStr}"
) (defaultNixConf // nixConf)
))
+ "\n";
nixpkgs = pkgs.path;
channel = pkgs.runCommand "channel-nixpkgs" { } ''
mkdir $out
${lib.optionalString bundleNixpkgs ''
ln -s ${nixpkgs} $out/nixpkgs
echo "[]" > $out/manifest.nix
''}
'';
baseSystem =
let
rootEnv = pkgs.buildPackages.buildEnv {
name = "root-profile-env";
paths = defaultPkgs;
};
manifest = pkgs.buildPackages.runCommand "manifest.nix" { } ''
cat > $out <<EOF
[
${lib.concatStringsSep "\n" (
builtins.map (
drv:
let
outputs = drv.outputsToInstall or [ "out" ];
in
''
{
${
lib.concatStringsSep "\n" (
builtins.map (output: ''
${output} = { outPath = "${lib.getOutput output drv}"; };
'') outputs
)
}
outputs = [ ${lib.concatStringsSep " " (builtins.map (x: "\"${x}\"") outputs)} ];
name = "${drv.name}";
outPath = "${drv}";
system = "${drv.system}";
type = "derivation";
meta = { };
}
''
) defaultPkgs
)}
]
EOF
'';
profile = pkgs.buildPackages.runCommand "user-environment" { } ''
mkdir $out
cp -a ${rootEnv}/* $out/
ln -sf ${manifest} $out/manifest.nix
'';
flake-registry-path =
if (flake-registry == null) then
null
else if (builtins.readFileType (toString flake-registry)) == "directory" then
"${flake-registry}/flake-registry.json"
else
flake-registry;
in
pkgs.runCommand "base-system"
{
inherit
passwdContents
groupContents
shadowContents
nixConfContents
;
passAsFile = [
"passwdContents"
"groupContents"
"shadowContents"
"nixConfContents"
];
allowSubstitutes = false;
preferLocalBuild = true;
}
(
''
env
set -x
mkdir -p $out/etc
mkdir -p $out/etc/ssl/certs
ln -s /nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt $out/etc/ssl/certs
cat $passwdContentsPath > $out/etc/passwd
echo "" >> $out/etc/passwd
cat $groupContentsPath > $out/etc/group
echo "" >> $out/etc/group
cat $shadowContentsPath > $out/etc/shadow
echo "" >> $out/etc/shadow
mkdir -p $out/usr
ln -s /nix/var/nix/profiles/share $out/usr/
mkdir -p $out/nix/var/nix/gcroots
ln -s /nix/var/nix/profiles $out/nix/var/nix/gcroots/profiles
mkdir $out/tmp
mkdir -p $out/var/tmp
mkdir -p $out/etc/nix
cat $nixConfContentsPath > $out/etc/nix/nix.conf
mkdir -p $out/root
mkdir -p $out/nix/var/nix/profiles/per-user/root
ln -s ${profile} $out/nix/var/nix/profiles/default-1-link
ln -s /nix/var/nix/profiles/default-1-link $out/nix/var/nix/profiles/default
ln -s /nix/var/nix/profiles/default $out/root/.nix-profile
ln -s ${channel} $out/nix/var/nix/profiles/per-user/root/channels-1-link
ln -s /nix/var/nix/profiles/per-user/root/channels-1-link $out/nix/var/nix/profiles/per-user/root/channels
mkdir -p $out/root/.nix-defexpr
ln -s /nix/var/nix/profiles/per-user/root/channels $out/root/.nix-defexpr/channels
echo "${channelURL} ${channelName}" > $out/root/.nix-channels
mkdir -p $out/bin $out/usr/bin
ln -s ${pkgs.coreutils}/bin/env $out/usr/bin/env
ln -s ${pkgs.bashInteractive}/bin/bash $out/bin/sh
''
+ (lib.optionalString (flake-registry-path != null) ''
nixCacheDir="/root/.cache/nix"
mkdir -p $out$nixCacheDir
globalFlakeRegistryPath="$nixCacheDir/flake-registry.json"
ln -s ${flake-registry-path} $out$globalFlakeRegistryPath
mkdir -p $out/nix/var/nix/gcroots/auto
rootName=$(${pkgs.nix}/bin/nix --extra-experimental-features nix-command hash file --type sha1 --base32 <(echo -n $globalFlakeRegistryPath))
ln -s $globalFlakeRegistryPath $out/nix/var/nix/gcroots/auto/$rootName
'')
);
layers = builtins.foldl' (
layersList: el:
let
layer = nix2container.buildLayer {
deps = el.contents;
layers = layersList;
};
in
layersList ++ [ layer ]
) [ ] layerContents;
image = nix2container.buildImage {
inherit name tag maxLayers;
inherit layers;
copyToRoot = [ baseSystem ];
initializeNixDatabase = true;
perms = [
{
path = baseSystem;
regex = "(/var)?/tmp";
mode = "1777";
}
];
config = {
Cmd = [ "/root/.nix-profile/bin/bash" ];
Env = [
"USER=root"
"PATH=${
lib.concatStringsSep ":" [
"/root/.nix-profile/bin"
"/nix/var/nix/profiles/default/bin"
"/nix/var/nix/profiles/default/sbin"
]
}"
"MANPATH=${
lib.concatStringsSep ":" [
"/root/.nix-profile/share/man"
"/nix/var/nix/profiles/default/share/man"
]
}"
"SSL_CERT_FILE=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
"GIT_SSL_CAINFO=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
"NIX_SSL_CERT_FILE=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt"
"NIX_PATH=/nix/var/nix/profiles/per-user/root/channels:/root/.nix-defexpr/channels"
];
};
};
in
image
// {
# We don't ship the tarball as the default output because it is a strange thing to want imo
tarball =
pkgs.buildPackages.runCommand "docker-image-tarball-${pkgs.nix.version}"
{
nativeBuildInputs = [ pkgs.buildPackages.bubblewrap ];
meta.description = "Docker image tarball with Lix for ${pkgs.system}";
}
''
mkdir -p $out/nix-support
image=$out/image.tar
# bwrap for foolish temp dir selection code that forces /var/tmp:
# https://github.com/containers/skopeo.git/blob/60ee543f7f7c242f46cc3a7541d9ac8ab1c89168/vendor/github.com/containers/image/v5/internal/tmpdir/tmpdir.go#L15-L18
mkdir -p $TMPDIR/fake-var/tmp
args=(--unshare-user --bind "$TMPDIR/fake-var" /var)
for dir in /*; do
args+=(--dev-bind "/$dir" "/$dir")
done
bwrap ''${args[@]} -- ${lib.getExe image.copyTo} docker-archive:$image
gzip $image
echo "file binary-dist $image" >> $out/nix-support/hydra-build-products
'';
meta = image.meta // {
description = "Docker image for Lix. This is built with nix2container; see that project's README for details";
longDescription = ''
Docker image for Lix, built with nix2container.
To copy it to your docker daemon, nix run .#dockerImage.copyToDockerDaemon
To copy it to podman, nix run .#dockerImage.copyTo containers-storage:lix
'';
};
}