guardrail to prevent conflicting linodes

create-linode.sh

@@ -66,6 +66,18 @@ fi
 # Linode API and be generally buggy and annoying in all further operations.
 if [[ "$SCRIPT_ACTION" == "c" && -n "$LINODE_LABEL" ]]; then
 
+  # Safety guard: this script administers a single Linode. Creating another
+  # while one already exists would leave two servers competing for the same
+  # volume, so refuse instead. The instances list reports the total number of
+  # Linodes in "results", which is 0 when nothing is running.
+  EXISTING_COUNT=$(curl -s -H "Authorization: Bearer $LINODE_API_KEY" \
+    https://api.linode.com/v4/linode/instances | jq -r '.results // 0')
+  if [[ "$EXISTING_COUNT" != "0" ]]; then
+    echo "ERROR: $EXISTING_COUNT Linode(s) already exist; this script manages a single instance." >&2
+    echo "       Destroy the existing one first: create-linode.sh d <label>" >&2
+    exit 1
+  fi
+
   # Creating a Linode also refreshes the valheim A record, reusing the update
   # block at the bottom of this script.
   UPDATE_A_RECORD="true"