Using ansible to manage disk space

Question

Simple ask: I want to delete some files if partition utilization goes over a certain percentage.

I have access to "size_total" and "size_available" via "ansible_mounts". i.e.:

ansible myhost -m setup -a 'filter=ansible_mounts'
myhost | success >> {
"ansible_facts": {
    "ansible_mounts": [
        {
            "device": "/dev/mapper/RootVolGroup00-lv_root", 
            "fstype": "ext4", 
            "mount": "/", 
            "options": "rw", 
            "size_available": 5033046016, 
            "size_total": 8455118848
        }, 

How do I access those values, and how would I perform actions conditionally based on them using Ansible?

Answer 1

In my case, all I care about is the root partition. But I found when using the example from frameloss above, that I needed a negated 'or' condition, because each mount point will get tested against the assertion. If more than one mount point existed, then that meant the assertion would always fail. In my example, I'm testing for if the size_available is less than 50% of size_total directly, rather than calculate it as frameloss did.

Secondly, at least in the version of ansible I used, it was necessary to include the {{ }} around the variable in with_items. A mistake that I made that wasn't in the example above was not aligning the 'when' clause at the same indentation as the 'fail' directive. ( If that mistake is made, then the solution does not work... )

# This works with ansible 2.2.1.0
- hosts: api-endpoints
  become: True
  tasks:

    - name: Test disk space available
      assert:
        that:
            - item.mount != '/' or {{ item.mount == '/' and item.size_available > (item.size_total|float * 0.4) }}
      with_items: '{{ ansible_mounts }}'
      ignore_errors: yes
      register: disk_free

    - name: Fail when disk space needs attention
      fail:
         msg: 'Disk space needs attention.'
      when: disk_free|failed

Answer 2

My solution

- name: cleanup logs, free disk space below 20%
  sudo: yes
  command: find /var -name "*.log" \( \( -size +50M -mtime +7 \) -o -mtime +30 \) -exec truncate {} --size 0 \;
  when: "item.mount == '/var' and ( item.size_available < item.size_total * 0.2 )"
  with_items: ansible_mounts

This will truncate any *.log files on the volume /var that are either older than 7 days and greater than 50M or older than 30 days if the free disk space falls below 20%.