Advanced Cron Job Management
While the basic usage of the Ansible cron
module is straightforward, there are several advanced techniques and features that can help you manage cron jobs more effectively.
Conditional Cron Job Execution
Sometimes, you may want to run a cron job only when certain conditions are met. You can achieve this by using Ansible's conditional statements, such as when
clauses:
- hosts: all
tasks:
- name: Run backup script if disk usage is above 80%
cron:
name: Run backup script
minute: "*/1"
job: /opt/scripts/backup.sh
when: ansible_facts['ansible_devices']['sda']['percent_used'] > 80
In this example, the cron job will only be created if the disk usage on the sda
device is above 80%.
Cron Job Templates
If you have multiple cron jobs that share similar configurations, you can use Jinja2 templates to make your Ansible playbooks more maintainable. Here's an example:
- hosts: all
tasks:
- name: Create cron job from template
cron:
name: "{{ item.name }}"
minute: "{{ item.minute }}"
job: "{{ item.job }}"
loop:
- { name: 'Run backup script', minute: '*/1', job: '/opt/scripts/backup.sh' }
- { name: 'Generate reports', minute: '0 3', job: '/opt/scripts/generate_reports.sh' }
loop_control:
loop_var: outer_item
In this example, the cron job configurations are defined as a list of dictionaries, which are then looped over and applied to the remote hosts.
Cron Job Validation
To ensure that your cron jobs are configured correctly, you can use the cron_job
lookup plugin to validate the existing cron jobs on the remote hosts:
- hosts: all
tasks:
- name: Validate cron jobs
assert:
that:
- "'Run backup script' in cron_job"
- "'Generate reports' in cron_job"
vars:
cron_job: "{{ lookup('cron_job') }}"
This task uses the cron_job
lookup plugin to retrieve the list of cron jobs on the remote hosts, and then asserts that the expected cron jobs are present.
By incorporating these advanced techniques, you can create more robust and flexible cron job management solutions with Ansible.