make zabbix external repo configurable

zabbix-repo/tasks/main.yml

@@ -6,7 +6,7 @@
   apt_key:
     data: "{{ lookup('file', 'zabbix.gpg') }}"
     state: present
-  when: debian_version == "stretch"
+  when: zabbix_external_repo
   notify:
     - update apt cache
   tags:
@@ -32,7 +32,7 @@
   apt_repository:
     repo: "{{ item }}"
     # yamllint disable-line rule:line-length
-    state: '{{ "present" if debian_version == "stretch" else "absent" }}'
+    state: '{{ "present" if zabbix_external_repo else "absent" }}'
   with_items:
     # yamllint disable-line rule:line-length
     - 'deb http://repo.zabbix.com/zabbix/{{ zabbix_version }}/debian {{ debian_version }} main'

zabbix-repo/vars/main.yml

@@ -2,3 +2,4 @@
 
 old_zabbix_version: "3.4"
 zabbix_version: "4.0"
+zabbix_external_repo: false