Ansible dynamic variable

Archives Ansible Project
1 
Im trying to have ansible Update variable value base on OS distribution, but Im faling when I insert the rules in a template.
Any idea how to solve this?

---
- hosts: fansible,cansible
  vars:
    nagios_freebsd_load: -w 75,70,65 -c 90,85,80
    nagios_centos_load: -w 15,10,5 -c 30,25,20
    nagios_server_load: vars['nagios_{{ ansible_distribution|lower }}_load']
  tasks:
    - name: Print server load variable 
      debug: msg="{{ nagios_server_load }}"
    - name: Print server load variable 
      debug: var="{{ nagios_server_load }}"
    - name: Copying file
      template:
        src: ~/ansitrial/load.conf
        dest: /tmp/load.conf

cat ~/ansitrial/load.conf 
{{ nagios_server_load }}

TASK [Print server load variable] *******************************************************************************************************************************************
ok: [fansible] => {
    "msg": "vars['nagios_freebsd_load']"
}
ok: [cansible] => {
    "msg": "vars['nagios_centos_load']"
}

TASK [Print server load variable] *******************************************************************************************************************************************
ok: [fansible] => {
    "vars['nagios_freebsd_load']": "-w 75,70,65 -c 90,85,80"
}
ok: [cansible] => {
    "vars['nagios_centos_load']": "-w 15,10,5 -c 30,25,20"
}

TASK [Copying file] *********************************************************************************************************************************************************
changed: [cansible]
changed: [fansible]

PLAY RECAP ******************************************************************************************************************************************************************
cansible                   : ok=4    changed=1    unreachable=0    failed=0   
fansible                      : ok=4    changed=1    unreachable=0    failed=0

remote@fansible:~ % cat /tmp/load.conf 
vars['nagios_freebsd_load']

[remote@cansible ~]$ cat /tmp/load.conf 
vars['nagios_centos_load']
2

To make it work use
nagios_server_load: "{{ vars['nagios_' ~ ansible_distribution|lower ~ '_load'] }}"