Ansible Cron Module with Examples

Automating repetitive tasks is one of the essential steps in large-scale environments. The Ansible cron module simplifies this by allowing administrators to manage cron jobs on remote systems. Cron jobs are scheduled tasks that run periodically based on time intervals. Using Ansible, you can easily create, modify, or remove cron jobs on multiple systems without logging into each server.

This guide will explore the Ansible cron module in-depth, including practical examples.

What is the Ansible Cron Module?

The cron module in Ansible is used to manage the crontab entries of users. It allows you to:

• Add new cron jobs
• Remove existing cron jobs
• Disable or enable specific jobs
• Specify commands, times, and additional options

The cron module is a part of Ansible’s core modules, making it readily available for most installations.

Basic Syntax

The basic syntax of the Ansible cron module is as follows:

- name: Manage a cron job
  ansible.builtin.cron:
    name: "Job Name"
    minute: "*"
    hour: "*"
    day: "*"
    month: "*"
    weekday: "*"
    job: "/path/to/command"
    state: "present"

Example 1. Adding a Cron Job

This example demonstrates how to add a cron job to run a script daily at midnight.

- name: Add a cron job to run a backup script
  hosts: all
  tasks:
    - name: Add a cron job for daily backups
      ansible.builtin.cron:
        name: "Daily Backup Job"
        minute: "0"
        hour: "0"
        job: "/usr/local/bin/backup.sh"
        state: present

This playbook adds a daily cron job on all hosts to run a backup script at midnight.

Example 2. Removing a Cron Job

To delete an existing cron job, create a playbook with the following content:

- name: Remove a specific cron job
  hosts: all
  tasks:
    - name: Remove the daily backup job
      ansible.builtin.cron:
        name: "Daily Backup Job"
        state: absent

This will remove a specific cron job named “Daily Backup Job” from all hosts.

3. Updating an Existing Cron Job

You can update a cron job by specifying the same name and modifying its properties.

- name: Update an existing cron job
  hosts: all
  tasks:
    - name: Change the time for the backup job
      ansible.builtin.cron:
        name: "Daily Backup Job"
        minute: "30"
        hour: "1"
        job: "/usr/local/bin/backup.sh"
        state: present

The above example updates the “Daily Backup Job” cron job on all hosts to run at 1:30 AM.

Example 4. Adding Cron Jobs with Environment Variables

You can add environment variables to a cron job.

- name: Add a cron job with environment variables
  hosts: all
  tasks:
    - name: Add a job with environment variables
      ansible.builtin.cron:
        name: "Job with Environment Variables"
        minute: "0"
        hour: "2"
        job: "/usr/local/bin/report.sh"
        env:
          PATH: "/usr/local/bin:/usr/bin:/bin"
          LANG: "en_US.UTF-8"
        state: present

This playbook adds a cron job named “Job with Environment Variables” on all hosts to run at 2:00 AM, including custom environment variables like PATH and LANG.

Example 5. Disabling a Cron Job

Sometimes, you may want to disable a cron job temporarily.

- name: Disable a specific cron job
  hosts: all
  tasks:
    - name: Disable the daily backup job
      ansible.builtin.cron:
        name: "Daily Backup Job"
        state: disabled

You can use state: disabled to disable the “Daily Backup Job” cron job on all hosts without removing it.

Example 6. Adding a Cron Job for a Specific User

You can specify a different user for the cron job.

- name: Add a cron job for a specific user
  hosts: all
  tasks:
    - name: Add a cron job for user 'john'
      ansible.builtin.cron:
        name: "User-Specific Job"
        minute: "15"
        hour: "3"
        job: "/home/john/scripts/cleanup.sh"
        user: "john"
        state: present

This playbook adds a cron job named “User-Specific Job” for the user “john” to run a cleanup script at 3:15 AM on all hosts.

Example 7. Managing Multiple Cron Jobs in a Playbook

You can manage multiple cron jobs in a single playbook.

- name: Manage multiple cron jobs
  hosts: all
  tasks:
    - name: Add a daily cleanup job
      ansible.builtin.cron:
        name: "Daily Cleanup"
        minute: "0"
        hour: "4"
        job: "/usr/local/bin/cleanup.sh"
        state: present

    - name: Add a weekly report generation job
      ansible.builtin.cron:
        name: "Weekly Report"
        minute: "30"
        hour: "5"
        weekday: "7"
        job: "/usr/local/bin/report.sh"
        state: present

This playbook adds two cron jobs on all hosts: a daily cleanup job at 4:00 AM and a weekly report generation job at 5:30 AM on Sundays.

Conclusion

The Ansible cron module is a powerful tool for managing scheduled tasks across multiple systems. With its flexibility and ease of use, it ensures consistency and reduces manual effort in cron job management.

You can explore the debug module to validate cron job tasks and the when statement to add conditional logic for dynamic scheduling.

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