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I am newbie to Ansible, i failed using ansible via command that way :

ansible host -a "/sbin/swapoff -a && /sbin/swapon -a"

Only this worked

ansible host -a "/sbin/swapoff -a
ansible host -a "/sbin/swapon -a

I am thinking of making a playbook, starting maybe with this:

- name: Turn off swap
  shell : "swapoff -a"

- name: Turn on swap
  shell : "swapon -a"

I would like to reset swap space with a condition, only when the swap used space is greater than 100mb. Is it possible to do that ?

Many thanks for your help

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You can certainly do this through a handler or task, but first you need to generate the trigger conditions. The swap space is in the Ansible facts that are returned when setup: is run. From the Ansible docs:

Facts

These are variables that contain information pertinent to the current host (inventory_hostname). They are only available if gathered first.

ansible_facts Contains any facts gathered or cached for the inventory_hostname Facts are normally gathered by the setup module automatically in a play, but any module can return facts.

ansible_local Contains any ‘local facts’ gathered or cached for the inventory_hostname. The keys available depend on the custom facts created. See the setup module for more details.

As an example:

ansible -i localhost, all -c local -m setup -a filter=*swap*
localhost | SUCCESS => {
    "ansible_facts": {
        "ansible_swapfree_mb": 437,
        "ansible_swaptotal_mb": 979
    },
    "changed": false
}

In your playbook your task to reset swap should then have the conditional like:

when: ansible_swap_free_mb < 500

In your case, however you want to trigger on swap used, so you would have to compute the difference between total and free.

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  • Many thanks for your answer, i need to check how i can use handler or task. It's very new for me. About one simple playbook i try that : ``` - hosts: host-test-bdd1 tasks: - name: We desactivate swap command: swapoff -a when: ansible_swap_free_mb < 1600 - name: We active swap command: swapon -a ``` But i still don't know where to put the condition "when" exactly – Peutre Oct 28 '19 at 12:58
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I have a solution on that way :

---
- hosts: hostnametest
  tasks:
   - name: we take swap space used (megabytes)
     shell : free -m | grep Swap | awk '{print $3}'
     register: swap_used

   - name: Turn off swap
     shell: "swapoff -a"
     when: (swap_used.stdout_lines[0] | int) > 100

   - name: Turn on swap
     shell: "swapon -a"
     when: (swap_used.stdout_lines[0] | int) > 100
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    Your first task should only be marked as changed when the threshold you want is exceeded. So move the "when" clause to a "changed_when" for the first task. – M_dk Oct 31 '19 at 9:30
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    Thanks for the comment, really perfect, i just did the "when" to "changed_when" for the first task, it works well ! Nice to learn this "changed_when" :) – Peutre Oct 31 '19 at 10:27

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