如何为本地和远程主机设置不同的python解释器 [英] how to set different python interpreters for local and remote hosts

问题描述

用例:

• 当我们第一次连接到远程主机时，远程主机已经安装了一些 python 版本 - 自动发现功能会找到它
• 现在我们在远程主机上安装ansible-docker
• 从现在开始:ansible-docker 文档 建议使用 ansible_python_interpreter=/usr/bin/env python-docker

• when we first connect to a remote host/s, the remote host will already have some python version installed - the auto-discovery feature will find it
• now we install ansible-docker on the remote host
• from this time on: the ansible-docker docs suggest to use ansible_python_interpreter=/usr/bin/env python-docker

我们再次连接到同一个主机，但现在我们必须使用 /usr/bin/env python-docker python 解释器

We connect to the same host/s again, but now we must use the /usr/bin/env python-docker python interpreter

这样做的最佳方法是什么?

目前我们在Playbook 2的playbook级别设置了ansible_python_interpreter:

Currently we set ansible_python_interpreter on the playbook level of Playbook 2:

---
- name: DaqMon app
  vars:
  - ansible_python_interpreter: "{{ '/usr/bin/env python-docker' }}"

这行得通，但这也会改变本地操作的python解释器.因此 本地操作 将失败，因为(python-docker 本地不存在).

This works, but this will also change the python interpreter of the local actions. And thus the local actions will fail, because (python-docker does not exist locally).

• 当前的解决方法是在每个本地操作上显式指定ansible_python_interpreter，这既乏味又容易出错

• the current workaround is to explicitly specify the ansible_python_interpreter on every local-action which is tedious and error-prone

问题:

• 理想的解决方案是，如果我们可以添加 '/usr/bin/env python-docker' 作为后备到 interpreter-python-fallback - 但我认为这是不可能的
• 有没有办法只为远程主机设置 python 解释器 - 并保留本地主机的默认值?
• 或者是否可以显式覆盖本地主机的 python 解释器?

• the ideal solution is, if we could add '/usr/bin/env python-docker' as fallback to interpreter-python-fallback - but I think this is not possible
• is there a way to set the python interpreter only for the remote hosts - and keep the default for the localhost?
• or is it possible to explicitly override the python interpreter for the local host?

推荐答案

感谢其他有用的答案，我找到了一个简单的解决方案:

Thanks to the other useful answers I found an easy solution:

• 在剧本层面，我们将 python 解释器设置为 /usr/bin/env python-docker
• 然后我们使用 set_fact 任务来覆盖本地主机的解释器
  • 我们还必须代表事实
  • 我们可以使用神奇的 ansible_playbook_python 变量，它指的是在(本地)Ansible 主机上使用的 Python 解释器来启动剧本:参见 Ansible 文档
  • on the playbook level we set the python interpreter to /usr/bin/env python-docker
  • then we use a set_fact task to override the interpreter for localhost only
    • we must also delegate the facts
    • we can use the magic ansible_playbook_python variable, which refers to the python interpreter that was used on the (local) Ansible host to start the playbook: see Ansible docs

    以下是Playbook 2开头的重要部分:

    Here are the important parts at the start of Playbook 2:

    ---
    - name: Playbook 2
      vars:
      - ansible_python_interpreter: "{{ '/usr/bin/env python-docker' }}"
      ...
      tasks:
      - set_fact:
          ansible_python_interpreter: '{{ ansible_playbook_python }}'
        delegate_to: localhost    
        delegate_facts: true
    

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