仅在特定组中的框上运行Ansible任务

Question

我正在尝试创建仅在特定组（称为pi）中的框上运行的任务。

我正在使用Ansible版本：

ansible 2.3.2.0
  config file = /Users/user/Development/raspbian-homeassistant/ansible.cfg
  configured module search path = Default w/o overrides
  python version = 3.6.3 (default, Dec  3 2017, 10:37:53) [GCC 4.2.1 Compatible Apple LLVM 9.0.0 (clang-900.0.38)]

这是我当前的代码：

- name: Set up zwave USB dongle
  when: inventory_hostname in groups['pi']
  blockinfile:
    path: /var/local/homeassistant/.homeassistant/configuration.yaml
    marker: "# {mark} ANSIBLE MANAGED BLOCK #"
    insertafter: "# zwave dongle"
    content: |2
      zwave:
        usb_path: /dev/ttyACM0
  tags:
    - config
    - hass

当主机名在组中时，它似乎可以正常工作，而在主机名不在时，则抛出错误。

这是我在无业游民的盒子（在组中vagrant）上运行时遇到的错误：

fatal: [192.168.33.123]: FAILED! => {"failed": true, "msg": "The conditional check 'inventory_hostname in groups['pi']' failed. The error was: error while evaluating conditional (inventory_hostname in groups['pi']): Unable to look up a name or access an attribute in template string ({% if inventory_hostname in groups['pi'] %} True {% else %} False {% endif %}).\nMake sure your variable name does not contain invalid characters like '-': argument of type 'StrictUndefined' is not iterable\n\nThe error appears to have been in '/Users/andy/Development/raspbian-homeassistant/ansible/roles/configure-hass/tasks/main.yml': line 21, column 3, but may\nbe elsewhere in the file depending on the exact syntax problem.\n\nThe offending line appears to be:\n\n\n- name: Set up zwave USB dongle\n  ^ here\n"}

检查列表中是否包含Ansible中的项目，建议我具有正确的语法，但我想这是针对较旧版本的Ansible吗？

我该如何解决？

Answer 1

通常，如果您希望任务仅适用于特定组中的主机，则可以通过创建针对该组的播放方式来做到这一点：

- hosts: pi
  tasks:
    - name: Set up zwave USB dongle
      blockinfile:
        path: /var/local/homeassistant/.homeassistant/configuration.yaml
        marker: "# {mark} ANSIBLE MANAGED BLOCK #"
        insertafter: "# zwave dongle"
        content: |2
          zwave:
            usb_path: /dev/ttyACM0
      tags:
        - config
        - hass

您收到的错误是因为is undefined. There are a couple of ways of preventing the error. For example, you can explicitly check that在尝试使用groups ['pi'] groups ['pi']`之前已对其进行了定义：

- name: set up zwave USB dongle
  when: groups['pi'] is defined and inventory_hostname in groups['pi']

或者，您可以使用default过滤器提供默认值：

- name: set up zwave USB dongle
  when: inventory_hostname in groups['pi']|default([])