python - 为什么 Ansible 上的 pre_task 将 ansible_python_version 验证为 2.7，然后验证为 3.6

Question

在我的剧本上，我正在尝试验证 Python 版本。在这个操作系统（Linux）上，我有两个版本的 Python：

python --version
Python 2.7.5

python3 --version
Python 3.6.8

我设置了一个 pre_task 来验证 Ansible 版本以及 Python 版本（示例）：

pre_tasks:
    - name: Validate we run with the correct Ansible version
      register: data
      assert:
        that:
          - ansible_version is defined
          - ansible_version.full is version('2.8.0.0', '>=')
          - ansible_python_version is defined
          - ansible_python_version is version('3.6.0', '>=')
        fail_msg: "'Python' version must be 3.6.0 and Ansible 2.8.0 minimal version."
      delegate_to: localhost
      run_once: true

    - name: Get facts
      register: facts
      setup:
        filter: ansible_python_version
      run_once: true

    - name: Debug facts
      debug:
        var: facts

不幸的是，当我运行这个角色时它失败了，因为它似乎是先阅读 Python2，然后是 Python3。

这里要提到的重要一点是，我已经删除了 Ansible for Python2 示例：

ansible --version
ansible 2.9.1
  config file = /ripl-nginx/ansible.cfg
  configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.6/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.6.8 (default, Aug  7 2019, 17:28:10) [GCC 4.8.5 20150623 (Red Hat 4.8.5-39)]

当我执行 pre_task 它失败如下：

fatal: [hostname -> localhost]: FAILED! => {
    "assertion": "ansible_python_version is version('3.6.0', '>=')",
    "changed": false,
    "evaluated_to": false,
    "msg": "'Python' version must be 3.6.0 and Ansible 2.8.0 minimal version."
}

如果我将验证修改为 2.7.5，例如：

- ansible_python_version is version('2.7.5', '>=')

它完美地工作：

ok: [hostname] => {
    "facts": {
        "ansible_facts": {
            "ansible_python_version": "3.6.8"
        },
        "changed": false,
        "failed": false
    }
}

我注意到的是，如果我删除delegate_to: localhost参数，它首先会找到 Python2，我认为这是失败的原因（示例）：

pre_tasks:
    - name: Validate we run with the correct Ansible version
      register: data
      assert:
        that:
          - ansible_version is defined
          - ansible_version.full is version('2.8.0.0', '>=')
          - ansible_python_version is defined
          - ansible_python_version is version('2.7.5', '>=')
        fail_msg: "'Python' version must be 3.6.0 and Ansible 2.8.0 minimal version."
      run_once: true

    - name: Get facts
      register: facts
      setup:
        filter: ansible_python_version
      delegate_to: localhost
      run_once: true

    - name: Debug facts
      debug:
        var: facts

输出：

ok: [hostname] => {
    "facts": {
        "ansible_facts": {
            "ansible_python_version": "2.7.5"
        },
        "changed": false,
        "failed": false
    }
}

这是一个错误还是我缺少配置？

标签： pythonansible

Answer 1

问题的解决方案（如果您已将组 var 设置为ansible_python_interpreter: /usr/bin/python3）：

pre_tasks:
    - name: Validate we run with the correct Ansible version
      delegate_to: hostvars[inventory_hostname]['ansible_python_version']
      assert:
        that:
          - ansible_version is defined
          - ansible_version.full is version('2.8.0.0', '>=')
          - ansible_python_version is defined
          - ansible_python_version is version('3.6.0', '>=')
        fail_msg: "'Python' version must be 3.6.0 and Ansible 2.8.0 minimal version."
      run_once: True

输出样本：

TASK [Validate we run with the correct Ansible version] *************************************************************************************************************************************************************************************
ok: [hostname -> hostvars[inventory_hostname]['ansible_python_version']] => {
    "changed": false,
    "msg": "All assertions passed"
}

TASK [Debug] ********************************************************************************************************************************************************************************************************************************
ok: [hostname] => {
    "hostvars[inventory_hostname]['ansible_python_version']": "3.6.8"
}

如果首选方法是让解释器的全局配置可以像在 [defaults] 下的 main ansible.cfg 中那样完成，例如：

interpreter_python = /usr/bin/python3

请记住，您不能同时定义两者。ansible.cfg 文件中的全局变量或每个环境的全局变量。有关更多信息，请阅读官方文档（解释器发现）。