Ansible: how to call module `add_host` for all hosts of the play
Solution 1
As you noted, there's a thing about add_host
: BYPASS_HOST_LOOP = True
.
So it's a kind of forced run_once
.
If you don't mind running over hypervisors
in sequential manner, you can simply use serial: 1
:
- hosts: hypervisors
serial: 1
tasks:
- shell: virsh list | awk 'NR>2' | awk '{print $2}'
register: result_virsh
- add_host:
name: "{{ item }}"
group: "guests"
with_items: "{{ result_virsh.stdout_lines }}"
This ensures that every play batch consists of only one host, so add_host
executes for every host.
Solution 2
If you don't want to run the play serially you can aggregate the results with ansible_play_hosts
and map
. The results can be used in the next play.
- hosts: all
gather_facts: false
tasks:
- shell: virsh list | awk 'NR>2' | awk '{print $2}'
register: result_virsh
changed_when: false
- add_host:
name: "{{ item }}"
group: guests
changed_when: false
loop: "{{ ansible_play_hosts | map('extract', hostvars, 'result_virsh') | map(attribute='stdout_lines') | flatten }}"
- hosts: guests
gather_facts: false
tasks:
- ping:
This answer was derived from Ansible: Accumulate output across multiple hosts on task run.
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Nelson G.
Started to develop at ten with Basic. I really used the C and C++ language. Now I'm using Java/Spring/Spring-boot/Ansible
Updated on June 16, 2022Comments
-
Nelson G. almost 2 years
I'm creating a playbook with this play:
On hosts
hypervisors
:- retrieve list of virtual machines from all hosts
- use module
add_host
to add all of them in a new inventory group calledguests
My inventory:
[hypervisors] host1 host2
My playbook:
- hosts: hypervisors - shell: virsh list | awk 'NR>2' | awk '{print $2}' register: result_virsh - add_host: name: "{{ item }}" group: "guests" with_items: "{{ result_virsh.stdout_lines }}"
Module
add_host
bypasses the play host loop and only runs once for all the hosts in the play.Then it is called once (for host1), it's a particular case of the use of this module (see link above), as if the variable
run_once
was implicitly fixed totrue
.How can I use it for all hosts in group
hypervisors
?EDIT: Example to reproduce it on your computer with only localhost
Create file /tmp/host1_test to simulate a return of guests vm1 and vm2:
vm1 vm2
Create file /tmp/host2_test to simulate a return of guests vm3 and vm4:
vm3 vm4
Use this inventory (test_add_host.ini) with two hosts, both with fixed IP address 127.0.0.1:
[hypervisors] host1 ansible_host=127.0.0.1 test_filename=/tmp/host1_test host2 ansible_host=127.0.0.1 test_filename=/tmp/host2_test
Use this playbook (test_add_host.yml):
- hosts: hypervisors gather_facts: no tasks: - shell: "cat {{ test_filename }}" register: result_virsh - add_host: name: "{{ item }}" group: "guests" with_items: "{{ result_virsh.stdout_lines }}" - hosts: guests gather_facts: no tasks: - local_action: ping
Call this playbook locally with command:
ansible-playbook -c local -i test_add_host.ini test_add_host.yml
- First play call hosts host1 and host2
- Second play call hosts vm1 and vm2
What should I do to call all hosts (vm1, vm2, vm3 and vm4) in second play ?
-
Nelson G. about 7 yearsArgh! I don't mind running
hypervisors
in serial, It was so simple in fact! THANKS!