fix: reclaim remote nix store space before rebuild

nixos/kubeadm/modules/k8s-common.nix

@@ -60,6 +60,12 @@ in
   };
 
   nix.settings.trusted-users = [ "root" "micqdf" ];
+  nix.gc = {
+    automatic = true;
+    dates = "daily";
+    options = "--delete-older-than 3d";
+  };
+  nix.settings.auto-optimise-store = true;
 
   environment.variables = {
     KUBECONFIG = "/etc/kubernetes/admin.conf";

nixos/kubeadm/scripts/rebuild-and-bootstrap.sh

@@ -141,6 +141,14 @@ prepare_remote_nix_trust() {
   remote "$node_ip" "sudo systemctl restart nix-daemon 2>/dev/null || true"
 }
 
+prepare_remote_space() {
+  local node_ip="$1"
+  echo "==> Reclaiming disk space on $node_ip"
+  remote "$node_ip" "sudo nix-collect-garbage -d || true"
+  remote "$node_ip" "sudo nix store gc || true"
+  remote "$node_ip" "sudo rm -rf /tmp/nix* /tmp/nixos-rebuild* || true"
+}
+
 populate_nodes
 prepare_known_hosts
 export NIX_SSHOPTS="$SSH_OPTS"
@@ -155,11 +163,13 @@ detect_ssh_user "$PRIMARY_CP_IP"
 
 for node in "${CP_NAMES[@]}"; do
   prepare_remote_nix_trust "${NODE_IPS[$node]}"
+  prepare_remote_space "${NODE_IPS[$node]}"
   rebuild_node "$node" "${NODE_IPS[$node]}"
 done
 
 for node in "${WK_NAMES[@]}"; do
   prepare_remote_nix_trust "${NODE_IPS[$node]}"
+  prepare_remote_space "${NODE_IPS[$node]}"
   rebuild_node "$node" "${NODE_IPS[$node]}"
 done