Ansible regex_search fails when I try to use a group with error 'NoneType' object has not attribute 'group'

Question

I have a number of user public keys, obtained via rest call made with the URI module, and I want to pull out the uid contained within that key. Here is the relevant line of my role

- name: find users UID within key
  debug: 
    msg: uid is "{{ item.content | regex_search( 'unixid=(\d+)', '\\1') }}"

this fails with the error:

'NoneType' object has no attribute 'group'

If I use -vvv on ansible I find that it's failing on this line

file "/usr/lib/python3.6/site-package/ansible/plugins/filter/core.py", line 156, in regex_search
  match = int(re.match(r'\\(\d+)', arg).group(1))

By comparison if I do the same regex without the group search the command works fine, other then returning more then the id I want.

I was able to get the desired functionality by chaining two regex_search commands together, but it's ugly. I'd rather know why groups aren't working for regex_search.

Answer 1

regex_search is meant to return you the matches of the regex, not the groups, or at least in the current version of Ansible ^{(although there are signs that it should work on the latest version?)}.

You can work around this using regex_findall instead, but you'll have to add a first filter to deal with the list created:

Given the task:

- debug: 
    msg: >-
      uid is {{ 
        item.content | regex_findall('unixid=(\d+)', '\\1') | first 
      }}
  vars:
    item:
      content: 000 foo unixid=123 bar 987

This yields the recap:

ok: [localhost] => 
  msg: uid is "123"