ansible assign shell results specific hosts in hostvars using with_items - ansible

Question

Basically i want modify an existing hostvars.
I have a dynamically generated array of hosts named "flash_hosts"
flash_hosts = ['host1', 'host2']
and a shell script which looks up a value for each host.
In following non-working code i try to assign each host the specific result of the script
- name: Assign values to to host var
shell: "get-assigned-value.sh {{ item }}"
register: "{{ hostvars[item].mac=stdout }}"
with_items: "{{ flash_hosts }}"
How can i make this work in in ansible? Basically i understand that register will not allow me to assign the value to hostvars directly, but how can this be solved then, as i need to iterate over the hosts?

Answer 1

Use set_fact to debug your register results on host wise..
- name: Assign values to to host var
shell: "/path/to/get-assigned-value.sh {{ item }}"
register: fileout
with_items:
- host1
- host2
- set_fact:
firstHost: "{{ fileout.results[0] }}"
secondHost: "{{ fileout.results[1] }}"
- debug:
var: firstHost.stdout
- debug:
var: secondHost.stdout
in the above example, firstHost is whole result of shell script running on first host, and firstHost.stdout gives the output of corresponding host shell script result.

Answer 2

It's possible set_facts and delegate_to the flash_hosts with delegate_facts.
But, to create a variable in hostvars the host must be declared in the inventory(static or dynamic). It's not necessary the host is accessible. For example
$ cat hosts
host1
host2
The play below
- hosts: localhost
vars:
flash_hosts: ['host1', 'host2']
tasks:
- name: Assign values to to host var
command: "{{ playbook_dir }}/get-assigned-value.sh {{ item }}"
register: result
loop: "{{ flash_hosts }}"
- set_fact:
mac: "{{ item.stdout }}"
loop: "{{ result.results }}"
delegate_to: "{{ item.item }}"
delegate_facts: true
- debug:
msg: "{{ hostvars[item].mac }}"
loop: "{{ flash_hosts }}"
gives
ok: [localhost] => (item=host1) =>
msg: mac address of host1
ok: [localhost] => (item=host2) =>
msg: mac address of host2
with the script
$ cat get-assigned-value.sh
#!/bin/sh
case $1 in
host1)
printf "mac address of host1"
;;
host2)
printf "mac address of host2"
;;
*)
printf "unknown host"
exit 1
;;
esac
exit 0