How to compare kernel (or other) version numbers in Ansible - ansible

Question

For a role I'm developing I need to verify that the kernel version is greater than a particular version.
I've found the ansible_kernel fact, but is there an easy way to compare this to other versions? I thought I might manually explode the version string on the .'s and compare the numbers, but I can't even find a friendly filter to explode the version string out, so I'm at a loss.

Answer 1

There is a test for it:
{{ ansible_distribution_version is version('12.04', '>=') }}
{{ sample_version_var is version('1.0', operator='lt', strict=True) }}

Answer 2

To Print the host IP address if the kernel version is less than 3
Ansible Version : 2.0.0.2
---
- hosts: all
vars:
kernel_version: "{{ ansible_kernel }}"
tasks:
- name: 'kernel version from facts'
debug:
msg: '{{ansible_all_ipv4_addresses}} {{ansible_kernel}}'
when: ansible_kernel | version_compare('3','<')
**
In 2.5 version_compare was renamed to version
**

Answer 3

For ansible>=2.9 this won't work, as the test syntax is now strictly separated from filters.
https://docs.ansible.com/ansible/latest/user_guide/playbooks_tests.html
The working solution would be:
{{ sample_version_var is version('1.0', operator='lt', strict=True) }}
...

Answer 4

To compare a version number, such as checking if the ansible_facts['distribution_version'] version is greater than or equal to ‘12.04’, you can use the version test.
{{ ansible_facts['distribution_version'] is version('12.04', '>=') }}
When using version in a playbook or role, don’t use {{ }} as described in the FAQ
vars:
my_version: 1.2.3
tasks:
- debug:
msg: "my_version is higher than 1.0.0"
when: my_version is version('1.0.0', '>')
Check Ansible Doc for more info

Answer 5

Have you thought of using shell module instead? for example:
- name: Get Kernel version
shell: uname -r | egrep '^[0-9]*\.[0-9]*' -o
register: kernel_shell_output
- debug: msg="{{ kernel_shell_output.stdout}}"
- name: Add cstate and reboot bios if kernel is 4.8
shell: echo "do what yo need to do"
when: kernel_shell_output.stdout == "4.8"