nixpkgs/nixos/modules/installer/tools/nixos-prepare-root.sh
Dan Peebles f1708a9d7d make-disk-image: change to be less VM-centric
This changes much of the make-disk-image.nix logic (and thus most NixOS
image building) to use LKL to set up the target directory structure rather
than a Linux VM. The only work we still do in a VM is less IO-heavy stuff
that while still time-consuming, is less of the overall load. The goal is
to kill more of that stuff, but that will require deeper changes to NixOS
activation scripts and switch-to-configuration.pl, and I don't want to
bite off too much at once.
2017-04-24 02:30:00 +00:00

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#! @shell@
# This script's goal is to perform all "static" setup of a filesystem structure from pre-built store paths. Everything
# in here should run in a non-root context and inside a Nix builder. It's designed primarily to be called from image-
# building scripts and from nixos-install, but because it makes very few assumptions about the context in which it runs,
# it could be useful in other contexts as well.
#
# Current behavior:
# - set up basic filesystem structure
# - make Nix store etc.
# - copy Nix, system, channel, and misceallaneous closures to target Nix store
# - register validity of all paths in the target store
# - set up channel and system profiles
# Ensure a consistent umask.
umask 0022
set -e
mountPoint="$1"
channel="$2"
system="$3"
shift 3
closures="$@"
PATH="@coreutils@/bin:@nix@/bin:@perl@/bin:@utillinux@/bin:@rsync@/bin"
if ! test -e "$mountPoint"; then
echo "mount point $mountPoint doesn't exist"
exit 1
fi
# Create a few of the standard directories in the target root directory.
mkdir -m 0755 -p $mountPoint/dev $mountPoint/proc $mountPoint/sys $mountPoint/etc $mountPoint/run $mountPoint/home
mkdir -m 01777 -p $mountPoint/tmp
mkdir -m 0755 -p $mountPoint/tmp/root
mkdir -m 0755 -p $mountPoint/var
mkdir -m 0700 -p $mountPoint/root
ln -s /run $mountPoint/var/run
# Create the necessary Nix directories on the target device
mkdir -m 0755 -p \
$mountPoint/nix/var/nix/gcroots \
$mountPoint/nix/var/nix/temproots \
$mountPoint/nix/var/nix/userpool \
$mountPoint/nix/var/nix/profiles \
$mountPoint/nix/var/nix/db \
$mountPoint/nix/var/log/nix/drvs
mkdir -m 1775 -p $mountPoint/nix/store
# All Nix operations below should operate on our target store, not /nix/store.
# N.B: this relies on Nix 1.12 or higher
export NIX_REMOTE=local?root=$mountPoint
# Copy our closures to the Nix store on the target mount point, unless they're already there.
for i in $closures; do
# We support closures both in the format produced by `nix-store --export` and by `exportReferencesGraph`,
# mostly because there doesn't seem to be a single format that can be produced outside of a nix build and
# inside one. See https://github.com/NixOS/nix/issues/1242 for more discussion.
if [[ "$i" =~ \.closure$ ]]; then
echo "importing serialized closure $i to $mountPoint..."
nix-store --import < $i
else
# There has to be a better way to do this, right?
echo "copying closure $i to $mountPoint..."
for j in $(perl @pathsFromGraph@ $i); do
echo " $j... "
rsync -a $j $mountPoint/nix/store/
done
nix-store --option build-users-group root --register-validity < $i
fi
done
# Create the required /bin/sh symlink; otherwise lots of things
# (notably the system() function) won't work.
if [ ! -x $mountPoint/@shell@ ]; then
echo "Error: @shell@ wasn't included in the closure" >&2
exit 1
fi
mkdir -m 0755 -p $mountPoint/bin
ln -sf @shell@ $mountPoint/bin/sh
echo "setting the system closure to '$system'..."
nix-env "${extraBuildFlags[@]}" -p $mountPoint/nix/var/nix/profiles/system --set "$system"
ln -sfn /nix/var/nix/profiles/system $mountPoint/run/current-system
# Copy the NixOS/Nixpkgs sources to the target as the initial contents of the NixOS channel.
mkdir -m 0755 -p $mountPoint/nix/var/nix/profiles
mkdir -m 1777 -p $mountPoint/nix/var/nix/profiles/per-user
mkdir -m 0755 -p $mountPoint/nix/var/nix/profiles/per-user/root
if [ -z "$noChannelCopy" ] && [ -n "$channel" ]; then
echo "copying channel..."
nix-env --option build-use-substitutes false "${extraBuildFlags[@]}" -p $mountPoint/nix/var/nix/profiles/per-user/root/channels --set "$channel" --quiet
fi
mkdir -m 0700 -p $mountPoint/root/.nix-defexpr
ln -sfn /nix/var/nix/profiles/per-user/root/channels $mountPoint/root/.nix-defexpr/channels
# Mark the target as a NixOS installation, otherwise switch-to-configuration will chicken out.
touch $mountPoint/etc/NIXOS