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.
The key distinction I'm drawing is that there's a component that deals
with the store of the machine being built, and another component for
the store building it. The inner part of it assumes nothing from the
builder (doesn't need chroot or root powers) so it can run comfortably
inside a Nix build, as well as nixos-rebuild. I have some upcoming work
that will use that to significantly speed up and streamline image builds
for NixOS, especially on virtualized hosts like EC2, but it's also a
reasonable speedup on native hosts.
Since some changes to the setuid wrappers, there is a symlink involved
and it doesn't resolve correctly inside the chroot. Do the check inside
the chroot to make it work again.
This partially reverts commit 0aa7520670.
Fine for rsync to be in system path but we still need the explicit path
in nixos-install in case it is invoked from non-NixOS systems and also
to fix OVA test failure
See also 0aa7520670
cc @edolstra
This reverts commit 582313bafe.
Removing rsync is actually pointless because nixos-install depends on
it. So if it's part of the system closure, we may as well provide it
to users.
Probably with the next Nix release we can drop the use of rsync and
use "nix copy" instead.
Before this commit updating /var/setuid-wrappers/ folder introduced
a small window where NixOS activation scripts could be terminated
and resulted into empty /var/setuid-wrappers/ folder.
That's very unfortunate because one might lose sudo binary.
Instead we use two atomic operations mv and ln (as described in
https://axialcorps.com/2013/07/03/atomically-replacing-files-and-directories/)
to achieve atomicity.
Since /var/setuid-wrappers is not a directory anymore, tmpfs mountpoints
were removed in installation scripts and in boot process.
Tested:
- upgrade /var/setuid-wrappers/ from folder to a symlink
- make sure /run/setuid-wrappers-dirs/ legacy symlink is really deleted
- Replace hand-rolled version of nixos-install in make-disk-image by an
actual call to nixos-install
- Required a few cleanups of nixos-install
- nixos-install invokes an activation script which the hand-rolled version
in make-disk-image did not do. We remove /etc/machine-id as that's
a host-specific, impure, output of the activation script
Testing:
nix-build '<nixpkgs/nixos/release.nix>' -A tests.installer.simple passes
Also tried generating an image with:
nix-build -E 'let
pkgs = import <nixpkgs> {};
lib = pkgs.lib;
nixos = import <nixpkgs/nixos> {
configuration = {
fileSystems."/".device = "/dev/disk/by-label/nixos";
boot.loader.grub.devices = [ "/dev/sda" ];
boot.loader.grub.extraEntries = '"''"'
menuentry "Ubuntu" {
insmod ext2
search --set=root --label ubuntu
configfile /boot/grub/grub.cfg
}
'"''"';
};
};
in import <nixpkgs/nixos/lib/make-disk-image.nix> {
inherit pkgs lib;
config = nixos.config;
diskSize = 2000;
partitioned = false;
installBootLoader = false;
}'
Then installed the image:
$ sudo df if=./result/nixos.img of=/dev/sdaX bs=1M
$ sudo resize2fs /dev/disk/by-label/nixos
$ sudo mount /dev/disk/by-label/nixos /mnt
$ sudo mount --rbind /proc /mnt/proc
$ sudo mount --rbind /dev /mnt/dev
$ sudo chroot /mnt /nix/var/nix/profiles/system/bin/switch-to-configuration boot
[ … optionally do something about passwords … ]
and successfully rebooted to that image.
Was doing all this from inside a Ubuntu VM with a single user nix install.
- Fix --no-bootloader which didn't do what it advertised
- Hardcode nixbld GID so that systems which do not have a nixbld user
can still run nixos-install (only with --closure since they can't
build anything)
- Cleanup: get rid of NIX_CONF_DIR(=/tmp)/nix.conf and pass arguments instead
- Cleanup: don't assume that the target system has '<nixpkgs/nixos>' or
'<nixos-config>' to see if config.users.mutableUsers. Instead check if
/var/setuid-wrappers/passwd is there
Installing NixOS now works from a Ubuntu host (using --closure).
nix-build -A tests.installer.simple '<nixpkgs/nixos/release.nix>' succeeds ✓
If nixos-install is run on a machine with `nix.distributedBuilds = true`
the installation will fail at some point like this:
Died at /nix/store/4frhrl31cl7iahlz6vyvysy5dmr6xnh3-nix-1.10/libexec/nix/build-remote.pl line 115, <STDIN> line 1.
This is due to `nix.distributedBuilds` setting
NIX_BUILD_HOOK=/nix/store/.../build-remote.pl in the global environment,
which then gets confused in the minimal chroot created by nixos-install.
To avoid these kinds of issues with build hooks, just disable them in
the chroot.
Passing the chroot flag to nixos-install without arguments should now give you a
Bash shell as intended rather than try an empty path.
This was masked by the user's shell (usually /bin/bash) being defaulted to by
chroot, and being found since their paths used NixOS conventions.
When bootstrapping from other distributions, nixos-install is unable to find
various tools in the chroot since their paths aren't aware of NixOS conventions.
This makes a small change to existing code by specifying nixpkgs/nixos instead
of just nixos when running nix-instantiate in the chroot. I haven't tested this
outside of bootstrapping, but the same specification is used elsewhere in the
code so I don't see why it wouldn't work.
Since we're using HTTPS for the binary cache (introduced in faf0797) by
default, the binary cache should also be available during installation.
The file that is defined in SSL_CERT_FILE outside of the chroot is
copied over to /tmp/ca-cert.crt inside the chroot, so we have an
absolute path we can reference during nixos-install. However, this might
end up with the file not being cleaned up properly from outside of the
store, but neither would be /tmp/root so the cleanup issue needs to be
solved in another place (or commit to be more exact).
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
