From 140178d58ec12df71e31747850337cc64d70ae9c Mon Sep 17 00:00:00 2001
From: Rodrigo Arias Mallo <rodrigo.arias@bsc.es>
Date: Mon, 18 Sep 2023 11:22:24 +0200
Subject: [PATCH] Begin the nix store overlay

We need to disable the read-only bind mount, so we can directly bind
mount the overlay.
---
 m/module/shared-nix-store.nix | 18 ++++++++++++++++++
 m/owl1/configuration.nix      |  1 +
 m/owl2/configuration.nix      |  1 +
 3 files changed, 20 insertions(+)
 create mode 100644 m/module/shared-nix-store.nix

diff --git a/m/module/shared-nix-store.nix b/m/module/shared-nix-store.nix
new file mode 100644
index 0000000..1c19fd9
--- /dev/null
+++ b/m/module/shared-nix-store.nix
@@ -0,0 +1,18 @@
+{ ... }:
+{
+  # 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
+  fileSystems."/mnt/hut-nix-store" = {
+    device = "hut:/nix/store";
+    fsType = "nfs";
+    options = [ "ro" ];
+  };
+
+  # Create the work directory
+  #systemd.tmpfiles.rules = [
+  #  "d /mnt/nix-overlay/work 0550 1000 root root -"
+  #];
+}
diff --git a/m/owl1/configuration.nix b/m/owl1/configuration.nix
index 5afda72..052ea8a 100644
--- a/m/owl1/configuration.nix
+++ b/m/owl1/configuration.nix
@@ -5,6 +5,7 @@
     ../common/main.nix
     ../module/ceph.nix
     ../module/slurm-firewall.nix
+    ../module/shared-nix-store.nix
   ];
 
   # Select the this using the ID to avoid mismatches
diff --git a/m/owl2/configuration.nix b/m/owl2/configuration.nix
index 9636760..ce95fa2 100644
--- a/m/owl2/configuration.nix
+++ b/m/owl2/configuration.nix
@@ -5,6 +5,7 @@
     ../common/main.nix
     ../module/ceph.nix
     ../module/slurm-firewall.nix
+    ../module/shared-nix-store.nix
   ];
 
   # Select the this using the ID to avoid mismatches