jungle/m/module/shared-nix-store.nix
Rodrigo Arias Mallo 1fc6891dc6 Remove nix-daemon.socket dependency of /nix/store
The dependency causes a cycle as the nix store will be mounted after the
network is ready, which itself depends on the socket.target which
requires the nix-daemon.socket to be ready too.
2023-09-18 17:28:47 +02:00

67 lines
2.6 KiB
Nix

{ ... }:
{
# Don't make the nix store read-only, as this would prevent the overlay FS
# from being able to mount it.
boot.readOnlyNixStore = false;
# The nix-daemon.socket has an unnecessary dependency over the /nix/store
# mount point. But that mount point won't be provided until the network is
# ready. However, the network-address-eno1.service, has a dependency over
# sockets.target, causing a cycle.
# One solution is to make the nix-daemon.socket depend only on the socket
# patch (which is already covered by ConditionPathIsReadWrite =
# /nix/var/nix/daemon-socket), instead on the /nix/store.
systemd.sockets.nix-daemon.unitConfig = {
RequiresMountsFor = "/nix/var/nix/daemon-socket";
};
# Mount the hut nix store via NFS in read-only mode.
fileSystems."/mnt/hut-nix-store" = {
device = "hut:/nix/store";
fsType = "nfs";
options = [ "ro" ];
};
# A workdir is also needed, so setup a permanent dir using tmpfiles.
systemd.tmpfiles.rules = [
"d /mnt/nix-work 0700 root root -"
];
# Mount an overlay in /nix/store using as lower layer the NFS store and upper
# layer the disk nix store. The destination is still the nix store in
# /nix/store (confusing). We need rw access, as the daemon need to write the
# lock files to build derivations locally.
# HACK: Use /nix//store to prevent the overlay to be mounted on boot, see:
# https://github.com/NixOS/nixpkgs/blob/17a46d09ac123d0da3a26855bf3af7db01f9c751/nixos/lib/utils.nix#L14
fileSystems."/nix//store" = {
device = "overlay";
fsType = "overlay";
options = [
# We need the local-fs.target to be ready, so the network interfaces can
# be configured to the network.target is reached. So make this a netdev
# mount.
"_netdev"
"lowerdir=/mnt/hut-nix-store,upperdir=/nix/store,workdir=/mnt/nix-work"
"x-systemd.requires-mounts-for=/nix/store"
# We need to wait for the NFS mount
"x-systemd.requires-mounts-for=/mnt/hut-nix-store"
];
depends = [ "/nix/store" "/mnt/hut-nix-store" "/mnt/nix-work" ];
};
# Maybe we should move it to a systemd mount, so we avoid the /nix//store
# hack. Example (not tested):
# systemd.mounts = [
# {
# what = "overlay";
# type = "overlay";
# where = "/nix/store";
# options = "lowerdir=/mnt/hut-nix-store,upperdir=/nix/store,workdir=/mnt/nix-work";
# description = "Overlay nix store mount";
# requires = [ "hut-nix-store.mount" ];
# after = [ "mnt-hut\\x2dnix\\x2dstore.mount" ];
# before = [ "nix-daemon.service" ];
# }
# ];
}