nixpkgs/nixos/modules/installer/cd-dvd/channel.nix
Naïm Favier 364d3609cd
nixos/installer/cd-dvd: use filtered nixpkgs source
Pin the `nixpkgs` registry entry to the *filtered* nixpkgs source to
avoid copying the entire `.git` directory to the ISO when building
from a local checkout.

Also set `to` directly instead of the `flake.outPath` hack.
2022-12-04 14:54:18 +01:00

65 lines
2.5 KiB
Nix

# Provide an initial copy of the NixOS channel so that the user
# doesn't need to run "nix-channel --update" first.
{ config, lib, pkgs, ... }:
with lib;
let
# This is copied into the installer image, so it's important that it is filtered
# to avoid including a large .git directory.
# We also want the source name to be normalised to "source" to avoid depending on the
# location of nixpkgs.
# In the future we might want to expose the ISO image from the flake and use
# `self.outPath` directly instead.
nixpkgs = lib.cleanSource pkgs.path;
# We need a copy of the Nix expressions for Nixpkgs and NixOS on the
# CD. These are installed into the "nixos" channel of the root
# user, as expected by nixos-rebuild/nixos-install. FIXME: merge
# with make-channel.nix.
channelSources = pkgs.runCommand "nixos-${config.system.nixos.version}"
{ preferLocalBuild = true; }
''
mkdir -p $out
cp -prd ${nixpkgs.outPath} $out/nixos
chmod -R u+w $out/nixos
if [ ! -e $out/nixos/nixpkgs ]; then
ln -s . $out/nixos/nixpkgs
fi
${optionalString (config.system.nixos.revision != null) ''
echo -n ${config.system.nixos.revision} > $out/nixos/.git-revision
''}
echo -n ${config.system.nixos.versionSuffix} > $out/nixos/.version-suffix
echo ${config.system.nixos.versionSuffix} | sed -e s/pre// > $out/nixos/svn-revision
'';
in
{
# Pin the nixpkgs flake in the installer to our cleaned up nixpkgs source.
# FIXME: this might be surprising and is really only needed for offline installations,
# see discussion in https://github.com/NixOS/nixpkgs/pull/204178#issuecomment-1336289021
nix.registry.nixpkgs.to = {
type = "path";
path = nixpkgs;
};
# Provide the NixOS/Nixpkgs sources in /etc/nixos. This is required
# for nixos-install.
boot.postBootCommands = mkAfter
''
if ! [ -e /var/lib/nixos/did-channel-init ]; then
echo "unpacking the NixOS/Nixpkgs sources..."
mkdir -p /nix/var/nix/profiles/per-user/root
${config.nix.package.out}/bin/nix-env -p /nix/var/nix/profiles/per-user/root/channels \
-i ${channelSources} --quiet --option build-use-substitutes false \
${optionalString config.boot.initrd.systemd.enable "--option sandbox false"} # There's an issue with pivot_root
mkdir -m 0700 -p /root/.nix-defexpr
ln -s /nix/var/nix/profiles/per-user/root/channels /root/.nix-defexpr/channels
mkdir -m 0755 -p /var/lib/nixos
touch /var/lib/nixos/did-channel-init
fi
'';
}