Ansible sum register value - ansible

Question

How to get the sum of two hosts with Jinja2 filtering ansible
host1 and host 2
---
- name: Count Check
hosts: MYGROUP
gather_facts: true
user: sv_admin
tasks:
- name: count check
shell: cat /etc/hosts | wc -l
register: command_result
- debug:
var: command_result.stdout
- set_fact:
total_result: "{{ command_result.stdout | map('int') | sum(start=0) }}"
- debug:
msg: "Total count: {{ total_result }}"
Playbook Output
TASK [debug] *****************************************************************
ok: [Host-01] => {
"msg": "Total count: 134"
}
ok: [Host-02] => {
"msg": "Total count: 133"
}

Answer 1

Use extract and sum. For example, the playbook below
shell> cat playbook.yml
- hosts: test_01:test_03
gather_facts: false
tasks:
- shell: cat /etc/hosts | wc -l
register: command_result
- debug:
var: command_result.stdout
- set_fact:
total_result: "{{ ansible_play_hosts_all|
map('extract', hostvars, ['command_result', 'stdout'])|
map('int')|
sum }}"
run_once: true
- debug:
var: total_result
gives (abridged)
shell> ansible-playbook playbook.yml
PLAY [test_01:test_03] ****
TASK [shell] ****
changed: [test_01]
changed: [test_03]
TASK [debug] ****
ok: [test_01] => {
"command_result.stdout": " 62"
}
ok: [test_03] => {
"command_result.stdout": " 31"
}
TASK [set_fact] ****
ok: [test_01]
TASK [debug] ****
ok: [test_03] => {
"total_result": "93"
}
ok: [test_01] => {
"total_result": "93"
}
See serial
See the difference between ansible_play_hosts and ansible_play_hosts_all

Answer 2

You can use custom stats to do that: https://docs.ansible.com/ansible/latest/modules/set_stats_module.html
So for your case it would look like
---
- name: Count Check
hosts: MYGROUP
gather_facts: true
user: sv_admin
tasks:
- name: count check
shell: cat /etc/hosts | wc -l
register: command_result
- debug:
var: command_result.stdout
- set_fact:
host_result: "{{ command_result.stdout }}"
- debug:
msg: "Count for this host: {{ host_result }}"
- set_stats:
data: "{{ { 'total_count': host_result | int } }}"
Then if you run it with ANSIBLE_SHOW_CUSTOM_STATS=yes it will show you the result at the end:
$ ANSIBLE_SHOW_CUSTOM_STATS=yes ansible-playbook -i inventory pb.yml
... (usual output)
CUSTOM STATS: *************************************************************
RUN: { "total_count": 267}
The set_stats task adds results together from all the hosts by default, which is what you are looking for. You need to make sure the values are integers though, because if they are strings it will just concatenate them and you will end up with something like RUN: { "total_count": "134133"}. That's why I have put the data: bit the way I have - if you try to create the dictionary in regular yaml, like
data:
total_count: "{{ host_result | int }}"
you will see that the value is still a string (due to the way yaml/jinja works) and it won't work properly.