chore: update swap

Author: shellord

infra/terraform/user-data.sh

@@ -16,15 +16,20 @@ apt-get install -y \
 systemctl enable --now docker
 usermod -aG docker ubuntu  # takes effect on next login for 'ubuntu'
 
-# Add swap space (2GB) to help with memory pressure
-fallocate -l 2G /swapfile
-chmod 600 /swapfile
-mkswap /swapfile
-swapon /swapfile
-echo '/swapfile none swap sw 0 0' >> /etc/fstab
-
-# Configure swappiness (how aggressively to use swap - 10 is conservative)
-echo 'vm.swappiness=10' >> /etc/sysctl.conf
+# Add swap space (2GB) to help with memory pressure (idempotent)
+if ! swapon --show | grep -q '^/swapfile'; then
+  SWAP_GB=2
+  fallocate -l ${SWAP_GB}G /swapfile || dd if=/dev/zero of=/swapfile bs=1M count=$((SWAP_GB*1024))
+  chmod 600 /swapfile
+  mkswap /swapfile
+  swapon /swapfile
+  # persist across reboots
+  grep -q '^/swapfile ' /etc/fstab || echo '/swapfile none swap sw 0 0' >> /etc/fstab
+fi
+# Conservative swappiness
+sysctl -w vm.swappiness=10
+echo 'vm.swappiness=10' > /etc/sysctl.d/99-swap.conf
+sysctl --system >/dev/null
 
 # K3s (pin to stable; adjust as you like)
 curl -sfL https://get.k3s.io | INSTALL_K3S_CHANNEL=stable sh -s - --write-kubeconfig-mode 640