How to alert via email in Ansible - automation

Question

I have setup a mail task in ansible to send emails if yum update is marked as 'changed'.
Here is my current working code:
- name: Send mail alert if updated
community.general.mail:
to:
- 'recipient1'
cc:
- 'recipient2'
subject: Update Alert
body: 'Ansible Tower Updates have been applied on the following system: {{ ansible_hostname }}'
sender: "ansible.updates#domain.com"
delegate_to: localhost
when: yum_update.changed
This works great, however, every system that gets updated per host group sends a separate email. Last night for instance I had a group of 20 servers update and received 20 separate emails. I'm aware of why this happens, but my question is how would I script this to add all the systems to one email? Is that even possible or should I just alert that the group was updated and inform teams of what servers are in each group? (I'd prefer not to take the second option)
Edit 1:
I have added the code suggested and am now unable to receive any emails. Here's the error message:
"msg": "The conditional check '_changed|length > 0' failed. The error was: error while evaluating conditional (_changed|length > 0): {{ hostvars|dict2items| selectattr('value.yum_update.changed')| map(attribute='key')|list }}: 'ansible.vars.hostvars.HostVarsVars object' has no attribute 'yum_update'\n\nThe error appears to be in '/tmp/bwrap_1073_o8ibkgrl/awx_1073_0eojw5px/project/yum-update-ent_template_servers.yml': line 22, column 7, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n - name: Send mail alert if updated\n ^ here\n",
I am also attaching my entire playbook for reference:
---
- name: Update enterprise template servers
hosts: ent_template_servers
tasks:
- name: Update all packages
yum:
name: '*'
state: latest
register: yum_update
- name: Reboot if needed
import_tasks: /usr/share/ansible/tasks/reboot-if-needed-centos.yml
- name: Kernel Cleanup
import_tasks: /usr/share/ansible/tasks/kernel-cleanup.yml
- debug:
var: yum_update.changed
- name: Send mail alert if updated
community.general.mail:
to:
- 'email#domain.com'
subject: Update Alert
body: |-
Updates have been applied on the following system(s):
{{ _changed }}
sender: "ansible.updates#domain.com"
delegate_to: localhost
run_once: true
when: _changed|length > 0
vars:
_changed: "{{ hostvars|dict2items|
selectattr('yum_update.changed')|
map(attribute='key')|list }}"
...
Ansible version is: 2.9.27
Ansible Tower version is: 3.8.3
Thanks in advance!

Answer 1

For example, the mail task below
- debug:
var: yum_update.changed
- community.general.mail:
sender: ansible
to: root
subject: Update Alert
body: |-
Updates have been applied to the following system:
{{ _changed }}
delegate_to: localhost
run_once: true
when: _changed|length > 0
vars:
_changed: "{{ hostvars|dict2items|
selectattr('value.yum_update.changed')|
map(attribute='key')|list }}"
TASK [debug] ***************************************************************
ok: [host01] =>
yum_update.changed: true
ok: [host02] =>
yum_update.changed: false
ok: [host03] =>
yum_update.changed: true
TASK [community.general.mail] **********************************************
ok: [host01 -> localhost]
will send
From: ansible#domain.com
To: root#domain.com
Cc:
Subject: Update Alert
Date: Wed, 09 Feb 2022 16:55:47 +0100
X-Mailer: Ansible mail module
Updates have been applied to the following system:
['host01', 'host03']
Remove the condition below if you want to receive also empty lists
when: _changed|length > 0
Debug
'ansible.vars.hostvars.HostVarsVars object' has no attribute 'yum_update'
Q: "What I could try?"
A: Some of the hosts are missing the variables yum_update. You can test it
- debug:
msg: "{{ hostvars|dict2items|
selectattr('value.yum_update.changed')|
map(attribute='key')|list }}"
run_once: true
Either make sure that the variable is defined on all hosts or use json_query. This filter tolerates missing attributes, e.g.
- debug:
msg: "{{ hostvars|dict2items|
json_query('[?value.yum_update.changed].key') }}"
run_once: true
Q: "The 'debug' task prior to the 'mail' task gives me the same output. But it fails when the 'mail' task is executed."
A: Minimize the code and isolate the problem. For example, in the code below you can see
Variable yum_update.changed is missing on host03
The filter json_query ignores this
The filter selectattr fails
- debug:
var: yum_update.changed
- debug:
msg: "{{ hostvars|dict2items|
json_query('[?value.yum_update.changed].key') }}"
run_once: true
- debug:
msg: "{{ hostvars|dict2items|
selectattr('value.yum_update.changed')|
map(attribute='key')|list }}"
run_once: true
gives
TASK [debug] **************************************************
ok: [host01] =>
yum_update.changed: true
ok: [host02] =>
yum_update.changed: false
ok: [host03] =>
yum_update.changed: VARIABLE IS NOT DEFINED!
TASK [debug] **************************************************
ok: [host01] =>
msg:
- host01
TASK [debug] **************************************************
fatal: [host01]: FAILED! =>
msg: |-
The task includes an option with an undefined variable.
The error was: 'ansible.vars.hostvars.HostVarsVars object'
has no attribute 'yum_update'
Both filters give the same results if all variables are present
TASK [debug] **************************************************
ok: [host01] =>
yum_update.changed: true
ok: [host02] =>
yum_update.changed: false
ok: [host03] =>
yum_update.changed: true
TASK [debug] **************************************************
ok: [host01] =>
msg:
- host01
- host03
TASK [debug] **************************************************
ok: [host01] =>
msg:
- host01
- host03