无法比较从 ansble_devices 事实返回的嵌套字典中键的值

如何解决无法比较从 ansble_devices 事实返回的嵌套字典中键的值

团队，我正在尝试比较来自 ansible_devices 变量并停留在语法错误处的键值的字符串值。我只想在满足 WHEN 条件时打印 msg。基本上，我只想在分区为 NULL 或其中没有值时打印 msg。

我有以下示例输出，我可以检索它，但现在我想将它与某个字符串进行比较，但失败了 值.yml

null_partitions: "{}"

  debug:
    msg: "{{ ansible_hostname }} {{ item }} {{ ansible_devices[item]['partitions'] }}"
  #when: "{{ ansible_devices[item]['partitions'] is defined }}"
  when: "ansible_devices[item]['partitions'] == ansible_devices[item] {{ null_partitions }}"
  with_items: "{{ ansible_devices }}"

输出错误：

 fatal: [node1]: FAILED! => {"msg": "The conditional check 'ansible_devices[item]['partitions'] == ansible_devices[item] {{ null_partitions }}' failed. The error was: template error while templating string: expected token 'end of statement block',got '{'. String: {% if ansible_devices[item]['partitions'] == ansible_devices[item] {} %} True {% else %} False {% endif %}\n\nThe error appears to be in '/ansible-managed/jenkins-slave/slave0/workspace/run_ansible_playbook/k8s/baremetal/roles/local_volume_mount/tasks/main.yml': line 15,column 3,but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n# As per the warning in your output,'when' clauses should not be wrapped with curly braces. Also better to use 'inventory_hostname' in this case\n- name: Print device partitions that are defined\n  ^ here\n"}

示例 ansible_Devices 如下

ok: [node1] => {
       "ansible_devices": {
           "loop0": {
               "holders": [],"host": "","links": {
                   "ids": [],"labels": [],"masters": [],"uuids": []
               },"model": null,"partitions": {},"removable": "0","rotational": "1","sas_address": null,"sas_device_handle": null,"scheduler_mode": "none","sectors": "0","sectorsize": "512","size": "0.00 Bytes","support_discard": "0","vendor": null,"virtual": 1
           },

我评论的 when 的输出如下

ok: [node] => (item=loop3) => {
      "msg": "node1 loop0 {}"
  }

根据评论，我试过了

when: "ansible_devices[item]['partitions'] ==  null_partitions"

输出是

  TASK [local_volume_mount : Print device partitions that are defined] 
skipping: [node] => (item=loop0)

不确定我的模式 {} 是否在值中定义错误？或者如果任务实际上是在寻找 null_partitions 作为字符串？

解决方法

"partitions": {} 不是一个包含 "{}" 的字符串，而是一个空字典。

因此，编写 when 子句的正确且安全的方法是检查变量是否为 mapping 以及是否具有 0 长度（即没有声明的键）。

when:
  - ansible_devices[item]['partitions'] is mapping
  - ansible_devices[item]['partitions'] | length == 0

关于 mapping 测试，请参阅 https://jinja2docs.readthedocs.io/en/stable/templates.html#list-of-builtin-tests

,

在@jack 评论的部分帮助下，我能够弄清楚。

when: "ansible_devices[item]['partitions'] ==  {{ null_partitions }}"

变量替换需要花括号。

输出

ok: [node1] => (item=loop0) => {
14:36:45      "msg": "node1 loop0 {}"
14:36:45  }