Use 'inventory_hostname' instead of 'ansible_fqdn'

While 'ansible_fdqn' can be changed by a compromised host,
'inventory_hostname' can't (hopefully).

It should therefore no longer be possible for the said host to access
the backups of another host.

roles/borgbackup_client/tasks/main.yml

@@ -51,7 +51,7 @@
     group: root
     mode: u=rw,g=r,o=
   vars:
-    borg_host_dir: "/borg/{{ ansible_fqdn }}"
+    borg_host_dir: "/borg/{{ inventory_hostname }}"
 
 - name: Create SSH key
   openssh_keypair:
@@ -63,36 +63,11 @@
     mode: u=rw,g=,o=
   register: ssh_key
 
-#- name: Gather server facts
-#  delegate_to: "{{ borg_server_host }}"
-#  delegate_facts: true
-#  setup:
-#    gather_subset:
-#      - all
-#  register: server_facts
-#
-#- name: Add server key to known hosts
-#  known_hosts:
-#    hash_host: true
-#    host: "{{ hostname }}"
-#    key: "{{ hostname }} {{ facts['ansible_ssh_host_key_' + item + '_public_keytype'] }} {{ facts['ansible_ssh_host_key_' + item + '_public'] }}"
-#  loop:
-#    - ecdsa
-#    - ed25519
-#    - rsa
-#  vars:
-#    hostname: {{ borg_server_host }}
-#    facts: {{ server_facts['ansible_facts'] }}
-
 - name: Gather SSH host keys
   delegate_to: "{{ borg_server_host }}"
   command: "ssh-keyscan {{ borg_server_host }}"
   register: keys
 
-- name: DEBUG
-  debug:
-    var: keys.stdout_lines
-
 - name: Add server key to known hosts
   known_hosts:
     hash_host: true
@@ -109,7 +84,7 @@
     key: "{{ ssh_key.public_key }}"
     key_options: "{{ options | join(',') }}"
   vars:
-    borg_host_dir: "/borg/{{ ansible_fqdn }}"
+    borg_host_dir: "/borg/{{ inventory_hostname }}"
     options:
       - 'command="borg serve --restrict-to-path {{ borg_host_dir }}"'
       - no-agent-forwarding