From 4e290b1938a37b420cf709f8aab5a85a79b2ceef Mon Sep 17 00:00:00 2001
From: Graham McIntire <graham@mcintire.me>
Date: Wed, 11 Feb 2026 13:27:46 -0600
Subject: [PATCH] fix String.replace crash when YAML index is numeric

YAML parses bare numbers like `index: 0` as integers. coerce
index_template to string before calling String.replace in both
build_table_sensor and build_state_sensor.
---
 lib/towerops/snmp/profiles/dynamic.ex        |  6 ++--
 test/towerops/snmp/profiles/dynamic_test.exs | 37 ++++++++++++++++++++
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/lib/towerops/snmp/profiles/dynamic.ex b/lib/towerops/snmp/profiles/dynamic.ex
index 1e8b4ff5..1b346ac4 100644
--- a/lib/towerops/snmp/profiles/dynamic.ex
+++ b/lib/towerops/snmp/profiles/dynamic.ex
@@ -324,7 +324,8 @@ defmodule Towerops.Snmp.Profiles.Dynamic do
 
         template ->
           # Replace {{ $index }} with the actual OID index
-          String.replace(template, "{{ $index }}", oid_index)
+          # Coerce to string since YAML parses bare numbers (e.g. `index: 0`) as integers
+          template |> to_string() |> String.replace("{{ $index }}", oid_index)
       end
 
     %{
@@ -387,7 +388,8 @@ defmodule Towerops.Snmp.Profiles.Dynamic do
 
         template ->
           # Replace {{ $index }} with the actual OID index
-          String.replace(template, "{{ $index }}", oid_index)
+          # Coerce to string since YAML parses bare numbers (e.g. `index: 0`) as integers
+          template |> to_string() |> String.replace("{{ $index }}", oid_index)
       end
 
     %{
diff --git a/test/towerops/snmp/profiles/dynamic_test.exs b/test/towerops/snmp/profiles/dynamic_test.exs
index ebdd0b6a..6ee846ad 100644
--- a/test/towerops/snmp/profiles/dynamic_test.exs
+++ b/test/towerops/snmp/profiles/dynamic_test.exs
@@ -1110,5 +1110,42 @@ defmodule Towerops.Snmp.Profiles.DynamicTest do
       indices = count_sensors |> Enum.map(& &1.sensor_index) |> Enum.sort()
       assert indices == ["count_1", "count_2"]
     end
+
+    test "handles numeric index_template from YAML without crashing" do
+      # YAML parses bare numbers like `index: 0` as integers, not strings.
+      # This must not crash String.replace/4.
+      profile =
+        base_profile(%{
+          count_sensor_oids: [
+            %{
+              base_oid: "1.3.6.1.4.1.99999.1.1",
+              sensor_type: "count",
+              sensor_descr: "Memory Usage",
+              sensor_unit: "",
+              sensor_divisor: 1,
+              descr_oid: nil,
+              index_template: 0
+            }
+          ]
+        })
+
+      stub(SnmpMock, :get, fn _, _, _ -> {:error, :no_such_object} end)
+
+      stub(SnmpMock, :walk, fn _, oid, _ ->
+        case oid do
+          "1.3.6.1.4.1.99999.1.1" ->
+            {:ok, [%{oid: "1.3.6.1.4.1.99999.1.1.1", value: {:integer, 42}}]}
+
+          _ ->
+            {:ok, []}
+        end
+      end)
+
+      assert {:ok, sensors} = Dynamic.discover_sensors(profile, @client_opts)
+
+      count_sensors = Enum.filter(sensors, &(&1.sensor_type == "count"))
+      assert length(count_sensors) == 1
+      assert hd(count_sensors).sensor_index == "0"
+    end
   end
 end