Add exec tasks if service found

src/ops/tools/ansible.md

@@ -50,3 +50,17 @@ import_tasks.
 
 `ìnclude_tasks` will add all tasks to play run, even if the when condition is
 false.
+
+## Exec task(s) if a specific service is found
+
+```yaml
+- name: Is Docker running ?
+  service_facts:
+
+- name: Push Telegraf docker input config if needed
+  template:
+    src: inputs/input.docker.conf.j2
+    dest: /etc/telegraf/telegraf.d/input.docker.conf
+  notify: reload telegraf
+  when: "'docker' in services"
+```