fix node exporter with firewalld enabled

Fixes #223 (closed)

ansible/roles/install_node_exporter/tasks/main.yaml

@@ -58,3 +58,16 @@
     name: node_exporter
     state: restarted
     enabled: true
+
+- name: Collect facts about system services
+  ansible.builtin.service_facts:
+
+- name: Configure firewalld to allow prometheus
+  ansible.posix.firewalld:
+    port: "{{ node_exporter_port }}/tcp"
+    zone: public
+    state: enabled
+    permanent: true
+  when:
+    - "'firewalld.service' in ansible_facts.services"
+    - ansible_facts.services["firewalld.service"].state == "running"