Reassemble multiple capture groups from Ansible regex_search

Question

I retrieved a version string into 'myvar' like 00001.00022.00333 which I would like to move into my dict as 1.22.333

The regex is pretty simple, but I am unable to reassemble the capture groups. Can someone explain how to fix this?

set_fact:
  cacheable: yes
  mydict: "{{ mydict | combine({ 'version': myvar | regex_search('0*(\\d+)\\.0*(\\d+)\\.0*(\\d+)', '\\1.\\2.\\3') }) }}"

The output of the code above is [ "1" ] (an array) instead of "1.22.333".

Answer 1

Use regex_replace. No need to escape backslash if you put it into single quotes. For example,

  mydict: "{{ {'version': myvar|regex_replace(md_regex, md_replace)} }}"
  md_regex: '0*(\d+)\.0*(\d+)\.0*(\d+)'
  md_replace: '\1.\2.\3'

gives

  mydict:
    version: 1.22.333

The same result can be achieved without regex. For example,

  mydict: "{{ {'version': myvar.split('.')|map('int')|join('.')} }}"

---

Example of a complete playbook for testing

- hosts: all

  vars:

    myvar: 00001.00022.00333

    mydict: "{{ {'version': myvar|regex_replace(md_regex, md_replace)} }}"
    md_regex: '0*(\d+)\.0*(\d+)\.0*(\d+)'
    md_replace: '\1.\2.\3'

    mydict2: "{{ {'version': myvar.split('.')|map('int')|join('.')} }}"

  tasks:

    - debug:
        var: mydict

    - debug:
        var: mydict2

---

Q: "Show a working example for this all in a task, including vars in the task."

A: Simply put the variables into the vars at the task's level

    - debug:
        msg: "{{ {'version': myvar|regex_replace(md_regex, md_replace)} }}"
      vars:
        myvar: 00007.00088.00999
        md_regex: '0*(\d+)\.0*(\d+)\.0*(\d+)'
        md_replace: '\1.\2.\3'

gives

  msg:
    version: 7.88.999

---

See:

• Understanding variable precedence

• 7.3.2. Single-Quoted Style

• 7.3.1. Double-Quoted Style