add nagios to docker if exists

tasks/configure.yml

@@ -1,13 +1,15 @@
 ---
-# - name: Ensure Nagios is configured
-#   template:
-#     dest: /etc/nagios4/nagios.cfg
-#     src: templates/nagios.cfg.j2
-#     owner: "{{ nagios_user }}"
-#     group: "{{ nagios_group }}"
-#     mode: 0660
-#     backup: yes
-#   notify: Restart Nagios4
+- name: Check if docker group exists
+  shell: grep docker /etc/groups
+  register: docker_group
+
+- name: Add nagios to docker group if it exists
+  user:
+    name: nagios
+    append: true
+    groups:
+      - docker
+  when: docker_group.rc == 0
 
 - name: Ensure folder for Nagios configurations exists
   file:
@@ -134,4 +136,4 @@
   systemd:
     name: nagios4
     enabled: yes
-    state: started
+    state: started