在任务中使用“时”命令时，我使用了“注册表”命令。

Question

我在同一本剧本中有两项相同的任务：

1. when: var == "true"
2. when: var == "false"

这两个任务都在使用register: result，但第一个任务失败，第二个任务成功。

我试着使用block:，而不仅仅是when:，其行为也是一样的。

bug-when.yml

---

- hosts: localhost
  tasks:
    - name: when true
      debug:
        msg: "this is true"
      register: result
      when: var == "true"

     - name: when false
       debug:
         msg: "this is false"
       register: result
       when: var == "false"

     - name: print result
       debug:
         msg: "{{ result }}"

运行它的示例：

ansible-playbook bug-when.yml -e var=true


PLAY [localhost] ***************************************************************

TASK [setup] *******************************************************************
Thursday 09 May 2019  18:51:35 +0000 (0:00:02.018)       0:00:02.018 **********
ok: [localhost]

TASK [when true] ***************************************************************
Thursday 09 May 2019  18:51:35 +0000 (0:00:00.437)       0:00:02.456 **********
ok: [localhost] => {
    "msg": "this is true"
}

TASK [when false] **************************************************************
Thursday 09 May 2019  18:51:35 +0000 (0:00:00.027)       0:00:02.483 **********
skipping: [localhost]

TASK [print result] ************************************************************
Thursday 09 May 2019  18:51:36 +0000 (0:00:00.023)       0:00:02.506 **********
ok: [localhost] => {
    "msg": {
        "changed": false,
        "skip_reason": "Conditional check failed",
        "skipped": true
    }
}

PLAY RECAP *********************************************************************
localhost                  : ok=3    changed=0    unreachable=0    failed=0

第二个运行它的示例：

ansible-playbook bug-when.yml -e var=false


PLAY [localhost] ***************************************************************

TASK [setup] *******************************************************************
Thursday 09 May 2019  18:52:01 +0000 (0:00:02.019)       0:00:02.019 **********
ok: [localhost]

TASK [when true] ***************************************************************
Thursday 09 May 2019  18:52:01 +0000 (0:00:00.453)       0:00:02.472 **********
skipping: [localhost]

TASK [when false] **************************************************************
Thursday 09 May 2019  18:52:01 +0000 (0:00:00.024)       0:00:02.497 **********
ok: [localhost] => {
    "msg": "this is false"
}

TASK [print result] ************************************************************
Thursday 09 May 2019  18:52:02 +0000 (0:00:00.028)       0:00:02.525 **********
ok: [localhost] => {
    "msg": {
        "changed": false,
        "msg": "this is false"
    }
}

PLAY RECAP *********************************************************************
localhost                  : ok=3    changed=0    unreachable=0    failed=0

Answer 1

为了进一步阐述@b.enoit.be所说的话：

当您有这样的任务时：

- name: some task
  debug:
    msg: this is an example
  when: false
  register: result

这将更新result ，即使该任务被跳过。这允许您在随后的任务中查看是否跳过此任务：

- name: check if task was skipped
  debug:
    msg: previous task was skipped
  when: result is skipped

考虑在每个任务中注册一个不同的变量，然后：

- name: when true
  debug:
    msg: "this is true"
  register: result1
  when: var == "true"

 - name: when false
   debug:
     msg: "this is false"
   register: result2
   when: var == "false"

 - name: print result
   debug:
     msg: "{{ result1.msg if result2 is skipped else result2.msg }}"

Answer 2

您在这里看到的行为之所以发生，主要是因为任务总是被注册，主要是因为您可以自引用任务寄存器本身，而且如果任务本身并不总是注册任务，则此行为将失败。

因此，您需要做的是拥有两个不同的寄存器句柄，并对其结果和skipped属性进行操作，以正确地显示您的消息。

这是剧本：

---
- hosts: localhost
  tasks:
    - name: when true
      debug:
        msg: "this is true"
      register: result_is_true
      when: var == "true"

    - name: when false
      debug:
        msg: "this is false"
      register: result_is_false
      when: var == "false"

    - name: print result
      debug:
        msg: "{{ result_is_true if result_is_false is skipped else result_is_false }}"

下面是运行var is true时的运行

$ ansible-playbook so.yml -e var=true

PLAY [localhost] *******************************************************************************************************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************************************************************************************************
ok: [host1]

TASK [when true] *******************************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": "this is true"
}

TASK [when false] ******************************************************************************************************************************************************************************************
skipping: [host1]

TASK [print result] ****************************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": {
        "changed": false,
        "failed": false,
        "msg": "this is true"
    }
}

PLAY RECAP *************************************************************************************************************************************************************************************************
host1                      : ok=3    changed=0    unreachable=0    failed=0  

下面是var is false的结果

$ ansible-playbook so.yml -e var=false

PLAY [localhost] *******************************************************************************************************************************************************************************************

TASK [Gathering Facts] *************************************************************************************************************************************************************************************
ok: [host1]

TASK [when true] *******************************************************************************************************************************************************************************************
skipping: [host1]

TASK [when false] ******************************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": "this is false"
}

TASK [print result] ****************************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": {
        "changed": false,
        "failed": false,
        "msg": "this is false"
    }
}

PLAY RECAP *************************************************************************************************************************************************************************************************
host1                      : ok=3    changed=0    unreachable=0    failed=0  

不用说:我猜你把你的问题简化为MCVE，但你的游戏实际上可以像

---
- hosts: localhost
  tasks:
    - name: print result
      debug:
        msg: "{{ 'this is true' if var == true else 'this is false' }}"

它的运行：

$ ansible-playbook so.yml -e var=false

PLAY [localhost] ***********************************************************************************************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************************************************************************
ok: [host1]


TASK [print result] ********************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": "this is false"
}

PLAY RECAP *****************************************************************************************************************************************************************************************
host1                      : ok=2    changed=0    unreachable=0    failed=0   


$ ansible-playbook so.yml -e var=true

PLAY [localhost] ***********************************************************************************************************************************************************************************

TASK [Gathering Facts] *****************************************************************************************************************************************************************************

ok: [host1]

TASK [print result] ********************************************************************************************************************************************************************************
ok: [host1] => {
    "msg": "this is true"
}

PLAY RECAP *****************************************************************************************************************************************************************************************
host1                      : ok=2    changed=0    unreachable=0    failed=0  

这里有一个jinja内联if-表达式问题：https://stackoverflow.com/a/14215034/2123530。