Ansible 任务无论条件如何都运行

Question

如果我将字符串存储到 ansible 寄存器中，然后让其他任务仅在该寄存器包含某个值时运行，它们总是运行，而不管寄存器中的值如何。

为什么当条件失败时 ansible 运行任务？

这是一个简单的例子。它应该只调试一次（如test_foo.stdout == "Foo"），但它会打印两个调试语句：

- name: foo
  command: "echo \"Foo\""
  register: test_foo
  tags: [ 'foo-test' ]

- debug:
    var: test_foo
  when: test_foo.stdout == "Foo",
  tags: [ 'foo-test' ]

- debug:
    var: test_foo
  when: test_foo.stdout == "Bar",
  tags: [ 'foo-test' ]

请注意，当使用相同条件触发另一个命令调用时也会发生这种情况，而不仅仅是调试调用。它将始终执行这两个任务。

这是输出：

TASK [test : foo] ***********************************************************************************************************************************************************************************
changed: [localServer -> localhost] => {"changed": true, "cmd": ["echo", "Foo"], "delta": "0:00:01.002745", "end": "2020-11-17 11:22:25.733089", "rc": 0, "start": "2020-11-17 11:22:24.730344", "stderr": "", "stderr_lines": [], "stdout": "Foo", "stdout_lines": ["Foo"]}

TASK [test : debug] *********************************************************************************************************************************************************************************
ok: [localServer] => {
    "test_foo": {
        "changed": true,
        "cmd": [
            "echo",
            "Foo"
        ],
        "delta": "0:00:01.002745",
        "end": "2020-11-17 11:22:25.733089",
        "failed": false,
        "rc": 0,
        "start": "2020-11-17 11:22:24.730344",
        "stderr": "",
        "stderr_lines": [],
        "stdout": "Foo",
        "stdout_lines": [
            "Foo"
        ]
    }
}

TASK [test : debug] *********************************************************************************************************************************************************************************
ok: [localServer] => {
    "test_foo": {
        "changed": true,
        "cmd": [
            "echo",
            "Foo"
        ],
        "delta": "0:00:01.002745",
        "end": "2020-11-17 11:22:25.733089",
        "failed": false,
        "rc": 0,
        "start": "2020-11-17 11:22:24.730344",
        "stderr": "",
        "stderr_lines": [],
        "stdout": "Foo",
        "stdout_lines": [
            "Foo"
        ]
    }
}

以防万一这是特定于版本的奇怪东西，我使用的是 Ubuntu 20.04，这是我的版本：

$ ansible --version
ansible 2.9.6
  config file = /path/to/project/orchestration/ansible.cfg
  configured module search path = ['/home/myUser/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.8.5 (default, Jul 28 2020, 12:59:40) [GCC 9.3.0]

Answer 1

问题在于结尾的逗号。下面的任务按预期工作并给出“msg: false”

    - debug:
        msg: '{{ "A" == "B" }}'

结尾的逗号创建一个tuple

    - debug:
        msg: '{{ "A" == "B", }}'
    - debug:
        msg: "{{ (false,)|type_debug }}"

给予

  msg: (False,)

  msg: tuple

非空变量，包括元组，计算结果为 true

    - debug:
        msg: OK
      when: (A,)

给予

  msg: OK

见CONDITIONAL_BARE_VARS

Answer 2

我刚刚将您的代码复制到我的实验室 VM 中，我注意到您在“when”语句的末尾使用了一个逗号（我从未见过）。我已删除它们并获得预期的输出。

当变量为 Foo 时：

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

TASK [foo] *********************************************************************************************************************
changed: [localhost]

TASK [debug] *******************************************************************************************************************
ok: [localhost] => {
    "test_foo": {
        "changed": true,
        "cmd": [
            "echo",
            "Foo"
        ],
        "delta": "0:00:00.006168",
        "end": "2020-11-17 12:50:11.863107",
        "failed": false,
        "rc": 0,
        "start": "2020-11-17 12:50:11.856939",
        "stderr": "",
        "stderr_lines": [],
        "stdout": "Foo",
        "stdout_lines": [
            "Foo"
        ]
    }
}

TASK [debug] *******************************************************************************************************************
skipping: [localhost]

PLAY RECAP *********************************************************************************************************************
localhost                  : ok=2    changed=1    unreachable=0    failed=0

当变量为 Bar 时：

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

TASK [foo] *********************************************************************************************************************
changed: [localhost]

TASK [debug] *******************************************************************************************************************
skipping: [localhost]

TASK [debug] *******************************************************************************************************************
ok: [localhost] => {
    "test_foo": {
        "changed": true,
        "cmd": [
            "echo",
            "Bar"
        ],
        "delta": "0:00:00.006077",
        "end": "2020-11-17 12:53:24.142058",
        "failed": false,
        "rc": 0,
        "start": "2020-11-17 12:53:24.135981",
        "stderr": "",
        "stderr_lines": [],
        "stdout": "Bar",
        "stdout_lines": [
            "Bar"
        ]
    }
}

PLAY RECAP *********************************************************************************************************************
localhost                  : ok=2    changed=1    unreachable=0    failed=0

我的 ansible 版本是：

ansible 2.7.10
python version = 2.7.5