apt: check if cron is installed before adding a cron job

CHANGELOG.md

@@ -11,6 +11,7 @@ The **patch** part changes incrementally at each release.
 ## [Unreleased]
 
 ### Added
+* apt: check if cron is installed before adding a cron job
 * certbot : new role to install and configure certbot
 * evocheck: explicit PATH
 * evolinux-base: On debian 10 and later, add noexec on /dev/shm

apt/tasks/hold_packages.yml

@@ -55,6 +55,13 @@
   tags:
     - apt
 
+- name: Check if Cron is installed
+  shell: "dpkg --list 'cron' 2>/dev/null | grep -q -E '^(i|h)i'"
+  register: is_cron
+  changed_when: false
+  failed_when: false
+  check_mode: no
+
 - name: Check for held packages (script)
   cron:
     cron_file: apt-hold-packages
@@ -67,5 +74,6 @@
     day: "{{ apt_check_hold_cron_day }}"
     month: "{{ apt_check_hold_cron_month }}"
     state: "present"
+  when: is_cron.rc == 0
   tags:
     - apt