jungle/m/module/shared-nix-store.nix

32 lines
1.2 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;
# 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 = [ "lowerdir=/mnt/hut-nix-store,upperdir=/nix/store,workdir=/mnt/nix-work" ];
depends = [ "/nix/store" "/mnt/hut-nix-store" "/mnt/nix-work" ];
};
}