alloy(role): enable node exporter textfile collector

Enable the node exporter textfile collector, which allows for collecting
custom statistics in a simple way.
https://github.com/prometheus/node_exporter#textfile-collector

inventories/chaosknoten/group_vars/all.yaml

@@ -50,7 +50,10 @@ alloy_config_default: |
   }
 
   prometheus.exporter.unix "local_system" {
-    enable_collectors = ["systemd"]
+    enable_collectors = ["systemd", "textfile"]
+    textfile {
+      directory = "/var/lib/node_exporter_textfile/"
+    }
   }
 
   prometheus.scrape "scrape_metrics" {

inventories/z9/group_vars/all.yaml

@@ -50,7 +50,10 @@ alloy_config_default: |
   }
 
   prometheus.exporter.unix "local_system" {
-    enable_collectors = ["systemd"]
+    enable_collectors = ["systemd", "textfile"]
+    textfile {
+      directory = "/var/lib/node_exporter_textfile/"
+    }
   }
 
   prometheus.scrape "scrape_metrics" {

roles/alloy/tasks/main.yaml

@@ -1,6 +1,14 @@
 ---
 - name: Deploy Grafana Alloy with config
   block:
+    - name: Create directory for node_exporter textfile collector
+      ansible.builtin.file:
+        path: /var/lib/node_exporter_textfile
+        state: directory
+        mode: "0755"
+        owner: root
+        group: root
+
     - name: Install Alloy
       ansible.builtin.include_tasks: install.yaml