Reboot remote hosts - Ansible module reboot

How to reboot remote hosts with Ansible specifying the notification message to logged users, the delay seconds, and the verification command.

September 10, 2021

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How to reboot remote hosts with Ansible?

I’m going to show you a live demo with some simple Ansible code. I’m Luca Berton and welcome to today’s episode of Ansible Pilot.

Ansible reboot remote hosts

Today we’re talking about the Ansible module reboot. The full name is ansible.builtin.reboot which means is part of the collection of modules “builtin” with ansible and shipped with ansible-core. This module is pretty stable and out for years and supports a large variety of operating systems. The purpose is to reboot a remote machine, wait for it to go down, come back up, and respond to commands. For Windows targets, use the ansible.windows.win_reboot module instead.

Parameters

reboot_timeout integer - 600
msg string - “Reboot initiated by Ansible”
reboot_command string - “[OS specific]”
pre_reboot_delay integer - 0
post_reboot_delay integer - 0
test_command string - “whoami”
boot_time_command string - “cat /proc/sys/kernel/random/boot_id”

This module has not required parameters but some of them might are nice to know. Let me summarize the most useful parameters. The “reboot_timeout” defines how much time to expect before a machine returns up & running. The real timeout is double because of the process of reboot and test command success. The first step in the reboot process is to print a message to all the logged users. You could keep the default “Reboot initiated by Ansible” or customize using the “msg” parameter. Secondly is going to execute the reboot command, OS-specific. If you need a specific one, please customize the “reboot_command” parameter. You could define also some extra delay time using the “pre_reboot_delay” or “post_reboot_delay” integer. Both default to zero. Once rebooted the target host Ansible is going to verify the workstation fully working using a test command. The default is whoami, but you could customize using the “test_command” parameter. This module could return also the amount of time indeed for bootstrap process reading throw kernel, specifically /proc/sys/kernel/random/boot_id.

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demo

Let’s jump into a real-life playbook on how to reboot remote hosts with Ansible Playbook.

reboot.yml

---
- name: reboot module demo
  hosts: all
  become: true
  tasks:
    - name: reboot host(s)
      ansible.builtin.reboot:
        msg: "reboot by Ansible"
        pre_reboot_delay: 5
        post_reboot_delay: 10
        test_command: "whoami"

code with ❤️ in GitHub

Recap

Now you know how to reboot remote Linux hosts with Ansible. Subscribe to the YouTube channel, Medium, Website, Twitter, and Substack to not miss the next episode of the Ansible Pilot.