nixos-install: Make compatible with Nix 2.0

The use of Nix 2.0 significantly simplifies the installer, since we
can just pass a different store URI (--store /mnt) - it's no longer
needed to set up a chroot environment for the build, and to bootstrap
Nix into the chroot.

Also, commands that need to run in the installation (namely boot
loader installation and setting a root password) are now executed
using nixos-enter.

This also removes the need for nixos-prepare-root since any required
initialisation is done by Nix or by the activation script.
This commit is contained in:
Eelco Dolstra 2018-02-05 19:50:36 +01:00
parent 60cb23001a
commit e88f28965a
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
3 changed files with 61 additions and 139 deletions

View file

@ -11,15 +11,17 @@ tedious, so here is a quick way to see if the installer works
properly:
<screen>
$ nix-build -A config.system.build.nixos-install
# mount -t tmpfs none /mnt
# nixos-generate-config --root /mnt
$ nix-build '&lt;nixpkgs/nixos>' -A config.system.build.nixos-install
# ./result/bin/nixos-install</screen>
To start a login shell in the new NixOS installation in
<filename>/mnt</filename>:
<screen>
# ./result/bin/nixos-install --chroot
$ nix-build '&lt;nixpkgs/nixos>' -A config.system.build.nixos-enter
# ./result/bin/nixos-enter
</screen>
</para>

View file

@ -1,30 +1,17 @@
#! @shell@
# - make Nix store etc.
# - copy closure of Nix to target device
# - register validity
# - with a chroot to the target device:
# * nix-env -p /nix/var/nix/profiles/system -i <nix-expr for the configuration>
# * install the boot loader
set -e
shopt -s nullglob
export PATH=@path@:$PATH
# Ensure a consistent umask.
umask 0022
# Re-exec ourselves in a private mount namespace so that our bind
# mounts get cleaned up automatically.
if [ "$(id -u)" = 0 ]; then
if [ -z "$NIXOS_INSTALL_REEXEC" ]; then
export NIXOS_INSTALL_REEXEC=1
exec unshare --mount --uts -- "$0" "$@"
else
mount --make-rprivate /
fi
fi
# Parse the command line for the -I flag
extraBuildFlags=()
chrootCommand=(/run/current-system/sw/bin/bash)
buildUsersGroup="nixbld"
mountPoint=/mnt
while [ "$#" -gt 0 ]; do
i="$1"; shift 1
@ -42,8 +29,8 @@ while [ "$#" -gt 0 ]; do
mountPoint="$1"; shift 1
;;
--closure)
closure="$1"; shift 1
buildUsersGroup=""
# FIXME: --closure is a misnomer
system="$1"; shift 1
;;
--no-channel-copy)
noChannelCopy=1
@ -57,17 +44,13 @@ while [ "$#" -gt 0 ]; do
--show-trace)
extraBuildFlags+=("$i")
;;
--chroot)
runChroot=1
if [[ "$@" != "" ]]; then
chrootCommand=("$@")
fi
break
;;
--help)
exec man nixos-install
exit 1
;;
--debug)
set -x
;;
*)
echo "$0: unknown option \`$i'"
exit 1
@ -75,132 +58,78 @@ while [ "$#" -gt 0 ]; do
esac
done
set -e
shopt -s nullglob
if test -z "$mountPoint"; then
mountPoint=/mnt
fi
if ! test -e "$mountPoint"; then
echo "mount point $mountPoint doesn't exist"
exit 1
fi
# Get the path of the NixOS configuration file.
if test -z "$NIXOS_CONFIG"; then
NIXOS_CONFIG=/etc/nixos/configuration.nix
if [[ -z $NIXOS_CONFIG ]]; then
NIXOS_CONFIG=$mountPoint/etc/nixos/configuration.nix
fi
if [ ! -e "$mountPoint/$NIXOS_CONFIG" ] && [ -z "$closure" ]; then
echo "configuration file $mountPoint/$NIXOS_CONFIG doesn't exist"
if [[ ${NIXOS_CONFIG:0:1} != / ]]; then
echo "$0: \$NIXOS_CONFIG is not an absolute path"
exit 1
fi
# Builds will use users that are members of this group
extraBuildFlags+=(--option "build-users-group" "$buildUsersGroup")
# Inherit binary caches from the host
# TODO: will this still work with Nix 1.12 now that it has no perl? Probably not...
binary_caches="$(@perl@/bin/perl -I @nix@/lib/perl5/site_perl/*/* -e 'use Nix::Config; Nix::Config::readConfig; print $Nix::Config::config{"binary-caches"};')"
extraBuildFlags+=(--option "binary-caches" "$binary_caches")
# We only need nixpkgs in the path if we don't already have a system closure to install
if [[ -z "$closure" ]]; then
nixpkgs="$(readlink -f "$(nix-instantiate --find-file nixpkgs)")"
export NIX_PATH="nixpkgs=$nixpkgs:nixos-config=$mountPoint/$NIXOS_CONFIG"
fi
unset NIXOS_CONFIG
# These get created in nixos-prepare-root as well, but we want to make sure they're here in case we're
# running with --chroot. TODO: --chroot should just be split into a separate tool.
mkdir -m 0755 -p "$mountPoint/dev" "$mountPoint/proc" "$mountPoint/sys"
# Set up some bind mounts we'll want regardless of chroot or not
mount --rbind /dev "$mountPoint/dev"
mount --rbind /proc "$mountPoint/proc"
mount --rbind /sys "$mountPoint/sys"
# If we asked for a chroot, that means we're not actually installing anything (yeah I was confused too)
# and we just want to run a command in the context of a $mountPoint that we're assuming has already been
# set up by a previous nixos-install invocation. In that case we set up some remaining bind mounts and
# exec the requested command, skipping the rest of the installation procedure.
if [ -n "$runChroot" ]; then
mount -t tmpfs -o "mode=0755" none $mountPoint/run
rm -rf $mountPoint/var/run
ln -s /run $mountPoint/var/run
for f in /etc/resolv.conf /etc/hosts; do rm -f $mountPoint/$f; [ -f "$f" ] && cp -Lf $f $mountPoint/etc/; done
for f in /etc/passwd /etc/group; do touch $mountPoint/$f; [ -f "$f" ] && mount --rbind -o ro $f $mountPoint/$f; done
if ! [ -L $mountPoint/nix/var/nix/profiles/system ]; then
echo "$0: installation not finished; cannot chroot into installation directory"
exit 1
fi
ln -s /nix/var/nix/profiles/system $mountPoint/run/current-system
exec chroot $mountPoint "${chrootCommand[@]}"
if [ ! -e "$NIXOS_CONFIG" ] && [ -z "$closure" ]; then
echo "configuration file $NIXOS_CONFIG doesn't exist"
exit 1
fi
# A place to drop temporary closures
# A place to drop temporary stuff.
trap "rm -rf $tmpdir" EXIT
tmpdir="$(mktemp -d)"
# Build a closure (on the host; we then copy it into the guest)
function closure() {
nix-build "${extraBuildFlags[@]}" --no-out-link -E "with import <nixpkgs> {}; runCommand \"closure\" { exportReferencesGraph = [ \"x\" (buildEnv { name = \"env\"; paths = [ ($1) stdenv ]; }) ]; } \"cp x \$out\""
}
subs="local?trusted=1 https://cache.nixos.org/"
system_closure="$tmpdir/system.closure"
# Use a FIFO for piping nix-store --export into nix-store --import, saving disk
# I/O and space. nix-store --import is run by nixos-prepare-root.
mkfifo $system_closure
if [ -z "$closure" ]; then
expr="(import <nixpkgs/nixos> {}).system"
system_root="$(nix-build -E "$expr")"
system_closure="$(closure "$expr")"
else
system_root=$closure
# Create a temporary file ending in .closure (so nixos-prepare-root knows to --import it) to transport the store closure
# to the filesytem we're preparing. Also delete it on exit!
# Run in background to avoid blocking while trying to write to the FIFO
# $system_closure refers to
nix-store --export $(nix-store -qR $closure) > $system_closure &
# Build the system configuration in the target filesystem.
if [[ -z $system ]]; then
echo "building the configuration in $NIXOS_CONFIG..."
outLink="$tmpdir/system"
nix build --out-link "$outLink" --store "$mountPoint" "${extraBuildFlags[@]}" \
--substituters "$subs" \
-f '<nixpkgs/nixos>' system -I "nixos-config=$NIXOS_CONFIG"
system=$(readlink -f $outLink)
fi
channel_root="$(nix-env -p /nix/var/nix/profiles/per-user/root/channels -q nixos --no-name --out-path 2>/dev/null || echo -n "")"
channel_closure="$tmpdir/channel.closure"
nix-store --export $channel_root > $channel_closure
# Set the system profile to point to the configuration. TODO: combine
# this with the previous step once we have a nix-env replacement with
# a progress bar.
nix-env --store "$mountPoint" "${extraBuildFlags[@]}" \
--substituters "$subs" \
-p $mountPoint/nix/var/nix/profiles/system --set "$system"
# Populate the target root directory with the basics
@prepare_root@/bin/nixos-prepare-root "$mountPoint" "$channel_root" "$system_root" @nixClosure@ "$system_closure" "$channel_closure"
# Copy the NixOS/Nixpkgs sources to the target as the initial contents
# of the NixOS channel.
if [[ -z $noChannelCopy ]]; then
channelPath="$(nix-env -p /nix/var/nix/profiles/per-user/root/channels -q nixos --no-name --out-path 2>/dev/null || echo -n "")"
if [[ -n $channelPath ]]; then
echo "copying channel..."
mkdir -p $mountPoint/nix/var/nix/profiles/per-user/root
nix-env --store "$mountPoint" --substituters 'local?trusted=1' "${extraBuildFlags[@]}" \
-p $mountPoint/nix/var/nix/profiles/per-user/root/channels --set "$channelPath" --quiet
fi
fi
# nixos-prepare-root doesn't currently do anything with file ownership, so we set it up here instead
chown @root_uid@:@nixbld_gid@ $mountPoint/nix/store
# Grub needs an mtab.
ln -sfn /proc/mounts $mountPoint/etc/mtab
# Mark the target as a NixOS installation, otherwise switch-to-configuration will chicken out.
touch "$mountPoint/etc/NIXOS"
# Switch to the new system configuration. This will install Grub with
# a menu default pointing at the kernel/initrd/etc of the new
# configuration.
echo "finalising the installation..."
if [ -z "$noBootLoader" ]; then
NIXOS_INSTALL_BOOTLOADER=1 chroot $mountPoint \
/nix/var/nix/profiles/system/bin/switch-to-configuration boot
if [[ -z $noBootLoader ]]; then
echo "installing the boot loader..."
# Grub needs an mtab.
ln -sfn /proc/mounts $mountPoint/etc/mtab
NIXOS_INSTALL_BOOTLOADER=1 nixos-enter --root "$mountPoint" -- /run/current-system/bin/switch-to-configuration boot
fi
# Run the activation script.
chroot $mountPoint /nix/var/nix/profiles/system/activate
# Ask the user to set a root password.
if [ -z "$noRootPasswd" ] && chroot $mountPoint [ -x /run/wrappers/bin/passwd ] && [ -t 0 ]; then
echo "setting root password..."
chroot $mountPoint /run/wrappers/bin/passwd
# Ask the user to set a root password, but only if the passwd command
# exists (i.e. when mutable user accounts are enabled).
if [[ -z $noRootPasswd ]] && [ -t 0 ]; then
nixos-enter --root "$mountPoint" -c '[[ -e /nix/var/nix/profiles/system/sw/bin/passwd ]] && echo "setting root password..." && /nix/var/nix/profiles/system/sw/bin/passwd'
fi
echo "installation finished!"

View file

@ -29,17 +29,8 @@ let
nixos-install = makeProg {
name = "nixos-install";
src = ./nixos-install.sh;
inherit (pkgs) perl pathsFromGraph rsync;
nix = config.nix.package.out;
cacert = "${pkgs.cacert}/etc/ssl/certs/ca-bundle.crt";
root_uid = config.ids.uids.root;
nixbld_gid = config.ids.gids.nixbld;
prepare_root = nixos-prepare-root;
nixClosure = pkgs.runCommand "closure"
{ exportReferencesGraph = ["refs" config.nix.package.out]; }
"cp refs $out";
path = makeBinPath [ nixos-enter ];
};
nixos-rebuild =