Ansible regex_replace insert value after regex match

Question

I have a version variable, which I need to split and insert a . in between

I tried this

ansible localhost  -e version=300 -m debug -a "msg={{ version  | regex_replace('\d{1,2}', '.\g<0>' ) }}"

But the o/p is

TASK [debug] ********************************************************************************************************************************************************************************************************************************
ok: [localhost] =>
  msg: .30.0

There is a . getting .30.0 added in the first place. I can use regex_repace to remove the first. after that. But is there any other better way? Why is pattern putting the decimal point in the first place?

Answer 1

Q: "Why is pattern putting the decimal point in the first place?"

A: Regex \d{1,2} matches one or two digits. Given the string 300 this regex matches the first two digits30. It will be replaced with .\g<0> which gives

.30

Next match is 0 because only one digit has left. The replacement gives

.0

Put together the result is

.30.0

Q: "Is there any way I can directly insert "." (dot) after the second place? ie 30.0?"

A: For example the play

- hosts: localhost
  vars:
    my_string: '300'
  tasks:
    - debug:
        msg: "{{ my_string[0:2] ~ '.' ~ my_string[2:] }}"
    - debug:
        msg: "{{ my_string[:-1] ~ '.' ~ my_string[-1] }}"

gives

"msg": "30.0"
"msg": "30.0"