定义了 Ansible 变量，但仍会处理默认过滤器

Question

拿这段代码：

- 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")) }}'

过滤器插件如下所示：

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
        }

从这篇文章中我读到只有在未定义变量时才会执行默认值：https://docs.ansible.com/ansible/latest/user_guide/playbooks_filters.html#providing-default-values

我的变量已定义...但默认过滤器中的代码已被执行。

我在这里错过了什么？

Answer 1

您可以通过其他途径实现此目的，并使用 inline if 表达式而不是 default 过滤器。

因此，您的最后一个 set_fact 将变为：

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

鉴于剧本：

- 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

这将产生：

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

定义了 Ansible 变量，但仍会处理默认过滤器

Ansible variable is defined, yet default filter still gets processed

python

jinja2

ansible