nixos-rebuild: get Nix from channel

If our old Nix can’t evaluate the Nixpkgs channel, try the fallback
from the new channel /first/. That way we can upgrade Nix to a newer
version and support breaking changes to Nix (like seen in the upgrade
o Nix 2.0).

This change should be backported to older NixOS versions!
This commit is contained in:
Matthew Bauer 2019-02-20 20:02:20 -05:00
parent 266315c91d
commit 475c8aa018

View File

@ -260,6 +260,14 @@ if [ -n "$rollback" -o "$action" = dry-build ]; then
buildNix=
fi
nixSystem() {
machine="$(uname -m)"
if [[ "$machine" =~ i.86 ]]; then
machine=i686
fi
echo $machine-linux
}
prebuiltNix() {
machine="$1"
if [ "$machine" = x86_64 ]; then
@ -279,7 +287,9 @@ if [ -n "$buildNix" ]; then
nixDrv=
if ! nixDrv="$(nix-instantiate '<nixpkgs/nixos>' --add-root $tmpDir/nix.drv --indirect -A config.nix.package.out "${extraBuildFlags[@]}")"; then
if ! nixDrv="$(nix-instantiate '<nixpkgs>' --add-root $tmpDir/nix.drv --indirect -A nix "${extraBuildFlags[@]}")"; then
nixStorePath="$(prebuiltNix "$(uname -m)")"
if ! nixStorePath="$(nix-instantiate --eval '<nixpkgs/nixos/modules/installer/tools/nix-fallback-paths.nix>' -A $(nixSystem) | sed -e 's/^"//' -e 's/"$//')"; then
nixStorePath="$(prebuiltNix "$(uname -m)")"
fi
if ! nix-store -r $nixStorePath --add-root $tmpDir/nix --indirect \
--option extra-binary-caches https://cache.nixos.org/; then
echo "warning: don't know how to get latest Nix" >&2