fail2ban only if installed (#98)

* Add condition to only configure fail2ban if it is installed

* Add package_facts to determine if fail2ban is installed

* Added warning message by @DO1JLR 

+ Warning message by @DO1JLR 
   -> The message will prompt a warning to the user if fail2ban is not installed without stopping the execution.
+ removed trailing whitespaces

tasks/fail2ban.yml

@@ -7,6 +7,7 @@
     group: root
     mode: 0444
   notify: Restart fail2ban
+  when: "'fail2ban' in ansible_facts.packages"
 
 - name: Install fail2ban jail
   ansible.builtin.template:
@@ -16,3 +17,10 @@
     group: root
     mode: 0444
   notify: Restart fail2ban
+  when: "'fail2ban' in ansible_facts.packages"
+
+- name: warn if fail2ban is not installed
+  ansible.builtin.fail:
+    msg: "the package fail2ban is not installed. no fail2ban filters deployed."
+  when: "'fail2ban' not in ansible_facts.packages"
+  ignore_errors: true

tasks/main.yml

@@ -8,6 +8,10 @@
     - "{{ ansible_distribution | lower }}.yml"
     - "{{ ansible_os_family | lower }}.yml"
 
+- name: Gather installed packages for checks in the role (fail2ban)
+  ansible.builtin.package_facts:
+    manager: auto
+
 - name: "Check gitea version"
   ansible.builtin.shell: "set -eo pipefail; /usr/local/bin/gitea -v | cut -d' ' -f 3"
   args: