CODEWITHSUNDEEP
pythonansiblejinja2
KdgDev
KdgDev

Reputation: 14549

Ansible variable is defined, yet default filter still gets processed

Take this bit of code:

- name: One
  set_fact:
    test_var: "default_name"

- name: Two
  debug:
    msg: "{{ test_var is defined }}"
  
- name: Three
  set_fact:
    second_test_var: '{{ test_var | default(groups | my_custom_filter_plugin("should not execute")) }}'

The filter plugin looks like this:

def my_custom_filter_plugin(groups, txt):
    print(groups)
    return "Test"


class FilterModule(object):
    ''' Testing filters '''

    def filters(self):
        return {
            'my_custom_filter_plugin': my_custom_filter_plugin
        }

From this text I read that defaults only get executed if a variable is not defined: https://docs.ansible.com/ansible/latest/user_guide/playbooks_filters.html#providing-default-values

My variable is defined... and yet the code in the default filter gets executed.

What am I missing here?

Upvotes: 1

Views: 357

Answers (1)

β.εηοιτ.βε
β.εηοιτ.βε

Reputation: 39314

You can achieve this taking an other route and use an inline if expression instead of the default filter.

So, your last set_fact would become:

- name: Three
  set_fact:
    second_test_var: >-
      {{ 
        test_var 
          if test_var is defined 
          else groups | my_custom_filter_plugin("should not execute") 
      }}

Given the playbook:

- hosts: localhost
  gather_facts: no

  tasks:
    - set_fact:
        second_test_var: >-
          {{ 
            test_var 
              if test_var is defined 
              else I_do_not_exists | int 
          }}
      vars: 
        test_var: foobar

    - debug:
        var: second_test_var

    - name: Showing that doing the same with `default` errors
      set_fact:
        second_test_var: "{{ test_var | default(I_do_not_exists | int) }}"
      vars: 
        test_var: foobar

This would yield:

TASK [set_fact] *****************************************************************
ok: [localhost]

TASK [debug] ********************************************************************
ok: [localhost] => 
  second_test_var: foobar

TASK [Showing that doing the same with `default` errors] ************************
fatal: [localhost]: FAILED! => 
  msg: |-
    The task includes an option with an undefined variable. The error was: 'I_do_not_exists' is undefined
  
    The error appears to be in '/usr/local/ansible/play.yml': line 18, column 7, but may
    be elsewhere in the file depending on the exact syntax problem.
  
    The offending line appears to be:
  
  
        - name: Showing that doing the same with `default` errors
          ^ here

Upvotes: 1

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