Ansible：如何检查一个变量是否正在加载到剧本中？

Question

我正在尝试编写一个从组 vars 文件中加载 vars 然后检查变量是否存在的 playbook

我的剧本是这样的：

---
- hosts: "{{ target }}"
  roles:
    - app

  tasks:
  - name: alert if variable does not exist
    fail:
      msg: "{{ item }} is not defined"
    when: "{{ item }}" is not defined
    with_items:
      - country
      - city
      - street
...

我的库存文件包含

[app]
ansible-slave1
ansible-slave2

[db]
ansible-db

[multi:children]
app
db

我有 roles/app/vars/main.yml 包含

country: "France"
city: "Paris"

我期待的是输出“未定义街道”的剧本，但我有一个无法解决的语法问题

[vagrant@ansible-master vagrant]$ ansible-playbook --inventory-file=ansible_master_hosts test_variables.yml --extra-vars "target=ansible-slave1" --syntax-check
ERROR! Syntax Error while loading YAML.

The error appears to have been in '/vagrant/test_variables.yml': line 10, column 24, but may be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:

  msg: "{{ item }} is not defined"
when: "{{ item }}" is not defined
                   ^ here
We could be wrong, but this one looks like it might be an issue with
missing quotes.  Always quote template expression brackets when they
start a value. For instance:

    with_items:
      - {{ foo }}

Should be written as:

    with_items:
      - "{{ foo }}"

我会很高兴有任何提示。

谢谢

Answer 1

您在“when”语句的无效位置有“”。应该是这样的：

    msg: "{{ item }} is not defined"
 when: "{{ item }} is not defined"

所以输出将是：

failed: [hostname] (item=street) => {"changed": false, "item": "street", "msg": "street is not defined"}

Answer 2

有一个未解决的问题conditional is defined fails to capture undefined var 。

作为一种解决方法，我建议将 where 条件更改为以下内容：

when: "{{ item }}" == ""