From 1674b6a844761d4e5bd4a58b63f9bc92d1978ea1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Torjus=20H=C3=A5kestad?= <torjus@usit.uio.no>
Date: Sun, 8 Feb 2026 13:02:58 +0100
Subject: [PATCH] system: enable zram swap for all hosts

Provides compressed swap in RAM to prevent OOM kills during
nixos-rebuild on low-memory VMs (2GB). Removes duplicate zram
configs from jelly01 and nix-cache01.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
---
 hosts/jelly01/configuration.nix | 4 ----
 hosts/nix-cache01/default.nix   | 1 -
 hosts/nix-cache01/zram.nix      | 6 ------
 system/default.nix              | 1 +
 system/zram.nix                 | 8 ++++++++
 5 files changed, 9 insertions(+), 11 deletions(-)
 delete mode 100644 hosts/nix-cache01/zram.nix
 create mode 100644 system/zram.nix

diff --git a/hosts/jelly01/configuration.nix b/hosts/jelly01/configuration.nix
index 048ae1c..2e69519 100644
--- a/hosts/jelly01/configuration.nix
+++ b/hosts/jelly01/configuration.nix
@@ -64,9 +64,5 @@
   vault.enable = true;
   homelab.deploy.enable = true;
 
-  zramSwap = {
-    enable = true;
-  };
-
   system.stateVersion = "23.11"; # Did you read the comment?
 }
diff --git a/hosts/nix-cache01/default.nix b/hosts/nix-cache01/default.nix
index 435b31e..e5795a5 100644
--- a/hosts/nix-cache01/default.nix
+++ b/hosts/nix-cache01/default.nix
@@ -4,6 +4,5 @@
     ./configuration.nix
     ../../services/nix-cache
     ../../services/actions-runner
-    ./zram.nix
   ];
 }
diff --git a/hosts/nix-cache01/zram.nix b/hosts/nix-cache01/zram.nix
deleted file mode 100644
index 1b0509c..0000000
--- a/hosts/nix-cache01/zram.nix
+++ /dev/null
@@ -1,6 +0,0 @@
-{ ... }:
-{
-  zramSwap = {
-    enable = true;
-  };
-}
diff --git a/system/default.nix b/system/default.nix
index a04e2bb..9ba5d06 100644
--- a/system/default.nix
+++ b/system/default.nix
@@ -12,5 +12,6 @@
     ./pki/root-ca.nix
     ./sshd.nix
     ./vault-secrets.nix
+    ./zram.nix
   ];
 }
diff --git a/system/zram.nix b/system/zram.nix
new file mode 100644
index 0000000..bb90208
--- /dev/null
+++ b/system/zram.nix
@@ -0,0 +1,8 @@
+# Compressed swap in RAM
+#
+# Provides overflow memory during Nix builds and upgrades.
+# Prevents OOM kills on low-memory hosts (2GB VMs).
+{ ... }:
+{
+  zramSwap.enable = true;
+}