display message when regex does not match (task failed) - regex

Question

I want to display a message if the task failed. This is that I currently have. I can't seem to store the stdout
- hosts: localhost
vars:
regexp: '(?i)^\s*PASS_MAX_DAYS\s+[0-9]+\s*$'
pass_max_days: "{{ out.stdout_lines|
select('match', regexp)|first|split|last }}"
tasks:
- command: cat /tmp/login.defs
register: out
- debug:
var: pass_max_days
- debug:
msg: Less than 90 days
when: pass_max_days|int < 90
- debug:
msg: Exactly 90 days
when: pass_max_days|int == 90
- debug:
msg: More than 90 days
when: pass_max_days|int > 90
- debug:
msg: Does not match!
when: pass_max_days.rc != 0

Answer 1

Use block & rescue.
The task under rescue will be executed, only if a task in the block fails.
- hosts: localhost
vars:
regexp: '(?i)^\s*PASS_MAX_DAYS\s+[0-9]+\s*$'
pass_max_days: "{{ out.stdout_lines|
select('match', regexp)|first|split|last }}"
tasks:
- block:
- name: cat the file
command: cat /etc/login.defs
register: out
- name: line search
debug:
var: pass_max_days
- name: line check
debug:
msg: "{% if pass_max_days|int < 90 %}Less than 90 days{% elif pass_max_days|int == 90 %}Exactly 90 days{% elif pass_max_days|int > 90 %}More than 90 days{% endif %}"
rescue:
- name: Failure message
debug:
msg: "VARIABLE IS NOT DEFINED!"
Success:
TASK [cat the file] *************************************
changed: [localhost]
TASK [line search] **************************************
ok: [localhost] => {
"pass_max_days": "99999"
}
TASK [line check] ***************************************
ok: [localhost] => {
"msg": "More than 90 days"
}
Failure:
TASK [cat the file] *************************************
TASK [line search] **************************************
ok: [localhost] => {
"pass_max_days": "VARIABLE IS NOT DEFINED!"
}
TASK [line check] ***************************************
fatal: [localhost]: FAILED! => {"msg": "The task includes an option with an undefined variable. The error was: {{ out.stdout_lines| select('match', regexp)|first|split|last }}: Unable to look up a name or access an attribute in template string ({{ out.stdout_lines| select('match', regexp)|first|split|last }}).\nMake sure your variable name does not contain invalid characters like '-': descriptor 'split' for 'str' objects doesn't apply to a 'AnsibleUndefined' object\n\nThe error appears to be in '/root/ansible-test/max.yml': line 16, column 8, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n - name: line check\n ^ here\n"}
TASK [Failure message] *********************************************************
ok: [localhost] => {
"msg": "VARIABLE IS NOT DEFINED!"
}
If you want the tasks in block not to be executed at failure, use check_mode in lineinfile module to check if the line exists.
Register an output for the task, which will have the attribute changed as true, if the line is found, but it will not make any changes to the file.
- hosts: localhost
gather_facts: no
vars:
regexp: '(?i)^\s*PASS_MAX_DAYS\s+[0-9]+\s*$'
pass_max_days: "{{ out.stdout_lines | select('match', regexp)|first|split|last }}"
tasks:
- name: Check if line exists
lineinfile:
name: /etc/login.defs
regexp: "{{ regexp }}"
line: ""
state: present
check_mode: yes
register: check
- name: Failure message
debug:
msg: "VARIABLE IS NOT DEFINED!"
when: check is not changed
- block:
- name: cat the file
command: cat /etc/login.defs
register: out
- name: line check
debug:
msg: "{% if pass_max_days|int < 90 %}Less than 90 days{% elif pass_max_days|int == 90 %}Exactly 90 days{% elif pass_max_days|int > 90 %}More than 90 days{% endif %}"
when: check is changed