如何使用ansible和pip安装ansible

Question

您好，我正在尝试在ubuntu服务器Trusty64中使用vagrant和ansible安装带有pip的ansible。我使用角色安装python3，在角色中安装ansible是：

---
# tasks file for roles/ansible
- name: install pip3
  apt: name=python3-pip state=present
  tags: ansible

- name: install librerias dev
  apt: name=libssl-dev state=present
  tags: ansible

- name: install librerias essential
  apt: name=build-essential state=present
  tags: ansible

- name: install librerias libdev
  apt: name=libffi-dev state=present
  tags: ansible

- name: install librerias pydev
  apt: name=python-dev state=present
  tags: ansible

- name: install librerias pydev
  apt: upgrade=yes
  tags: ansible

- name: install setuptools
  command: pip3 install setuptools
  tags: ansible

- name: upgrade setuptools
  command: pip3 install --upgrade setuptools
  tags: ansible

- name: install ansible
  command: pip3 install ansible
  tags: ansible

安装python3和pip3后，安装ansible失败，出现下一个错误回溯：

Python 3.5 or later is required",                                                                   
    "stderr_lines": [
        "Traceback (most recent call last):", 
        "  File \"/usr/bin/pip3\", line 5, in <module>", 
        "    from pkg_resources import load_entry_point", 
        "  File \"/usr/local/lib/python3.4/dist-packages/pkg_resources/__init__.py\", line 93, in <module>", 
        "    raise RuntimeError(\"Python 3.5 or later is required\")", 
        "RuntimeError: Python 3.5 or later is required"
    ], 
    "stdout": "", 
    "stdout_lines": []
}

我不明白为什么我也要解决这个问题，因为我已经使用这个角色安装了python3：

---
# tasks file for roles/python3

- name: aniadir repositorio
  apt_repository: 
   repo: ppa:deadsnakes/ppa
   state: present

- name: actualizar cache
  apt: update_cache=yes

- name: instalar python3
  apt: name=python3.7 state=present

我已经使用pip3安装并升级了setuptools。谢谢你的帮助。谢谢

Answer 1

根据this answer，您需要添加：

- name: Select python3.7 as default python3
  alternatives:
    name: python3
    path: /usr/bin/python3.7

正如您在错误中看到的，Ansible尝试使用Python 3.4安装Ansible：

/usr/local/lib/python3.4/dist-packages/pkg_resources/__init__.py

Python3.4是您安装的默认Python3。安装Python3.7只会安装python3.7，但不会使其成为默认的Python3。为此，在调用python3时，必须使用alternatives system显式地告诉系统使用python3.7