On 15. sep. 2017 11:02, Sieds Pallas wrote:
Hi,
I am getting confused on the working and purpose of delegated_facts.
If I read the manual correctly:
http://docs.ansible.com/ansible/latest/playbooks_delegation.html#delegated-facts
when you delegate a task to another host than the current managed host from
the inventory hosts: list, the ansible facts are gathered from the
delegated host but assigned to the current inventory host.
Specifying "delegate_facts: True" would change this that the ansible facts
are assigned to the delegated host.
This is correct, and you example does show this.
I do not understand what they mean with that facts are assigned to a
particular host. When you run a playbook, as it loops over all "hosts:",
facts are gathered and the ansible_* variables get some value valid for
that iteration - so without some host qualifier.
I don't now where you have this from, but I think they are referring to
Ansible default behavior.
The fist thing Ansible does is to collect from all host, you can see
that in the output as "TASK [Gathering Facts]"
This behavior can be changed by the play directive "gather_facts"
The RedHat training manual DO407 (pp.295,296) is not sufficiently explicit
about this but appears confused, but from their example I get the
impression that it is the other way round.
Never seen it.
When I try it myself I see:
- with just "delegate_to: ", the ansible facts are gathered from the
delegated host, which is what I would expect if you run a task on a
delegated host;
- with in addition "delegated_facts: ", the ansible facts are gathered
instead from the current inventory host - which means that the name
"delegated_facts" is confusing.
I think you are being confused because Ansible gather_facts is default
true and facts is gathered from both hosts.
So is the documentation wrong?
No, they are correct.
How is delegated_facts supposed to work?
As your example, but I gonna give you a example that might show this
more clearly.
Here's the code and output:
<<<<<<<<<<<<<<<<
$ cat inventory
[invhosts]
node1
[delegates]
node2
$ cat testdelegate.yml
---
- name: test delegate functionality
hosts: invhosts
tasks:
- name: setup
setup:
delegate_to: "{{ item }}"
# delegate_facts: true
with_items: "{{ groups['delegates'] }}"
- name: show
debug: msg="from fact of {{ inventory_hostname }}, ansible_hostname =
{{ ansible_hostname }}.\n"
# debug: msg="from delegated fact of {{ inventory_hostname }},
ansible_hostname = {{ ansible_hostname }}.\n"
...
$ ansible-playbook testdelegate.yml
PLAY [test delegate functionality]
*******************************************************************************************************************************
TASK [Gathering Facts]
*******************************************************************************************************************************************
Here you see the default task where Ansible gather facts from all host.
Using your inventory try this code, maybe it show the feature more clear
since i turn off the default fact gathering.
---
- hosts: node1
gather_facts: no
tasks:
- setup:
delegate_to: node2
#delegate_facts: true
- debug: var=hostvars['node1'].ansible_hostname
- debug: var=hostvars['node2'].ansible_hostname
Run the playbook again after you uncomment delegate_facts.
Did this help?
--
Kai Stian Olstad
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