懒惰地评价变量

Question

我有一个变量引用，当Playbook启动和引用被评估时，这个变量是未知的。是否有一种在实际访问变量时延迟加载该变量的方法？

在清单中：

all:
  hosts:
    l01lin08:
      bamboo_agents_it:
        - bamboo_agent_app_name: bamboo-agent-it
          bamboo_agent_install_dir: /data/bamboo-agent-it
          bamboo_agent_capabilities: "{{ bamboo_agent_capabilities_it }}"
        - # ...
        - # ...
      bamboo_agent_capabilities_it:
        # Error: bamboo_agent_install_dir is not known when evaluating the variable
        capabilitiy: '{{ bamboo_agent_install_dir }}/bla/blubb'
        another.one: 123
        is.something: true

bamboo_agent_capabilities_it.capability对bamboo_agents_it[].bamboo_agent_install_dir的引用在此上下文中不为所知。

功能是一组键值对，它可以是所有的东西。这些值并不总是路径，键也不总是相同的。因此，我无法判断何时添加父路径，何时不在目标任务中。

在剧本中，我在bamboo_agents_it循环中调用一个角色

  tasks:
    Install all bamboo agents
    - include_role:
        name: bamboo-agent-linux
      vars:
        bamboo_agent_app_name: '{{ item.bamboo_agent_app_name }}'
        bamboo_agent_install_dir: '{{ item.bamboo_agent_install_dir }}'
        bamboo_agent_capabilities: '{{ item.bamboo_agent_capabilities }}'
      loop: '{{ bamboo_agents_it }}'

在这个循环中，item.bamboo_agent_install_dir是可用的，但是我希望有一个通用的配置定义。我不想把这些单钥匙分开处理。

• 是否有一种通用的方法来解决这个问题？
• 也许可以在访问它时在任务中加载变量吗？

我使用的一个解决方法是替换一个占位符。但我希望有更多的习惯方式：

# Inventory
      bamboo_agent_capabilities_it:
        # Error: bamboo_agent_install_dir is not known when evaluating the variable
        capabilitiy: '[bamboo_agent_install_dir]/bla/blubb'

# Task:
  lineinfile:
    path: '{{ bamboo_agent_install_dir }}/bin/bamboo-capabilities.properties'
    line: '{{ item.key }}={{ item.value | replace("[bamboo_agent_install_dir]", bamboo_agent_install_dir) }}'
  loop: '{{ bamboo_agent_default_capabilities | dict2items + bamboo_agent_capabilities | dict2items }}'

Answer 1

您可以做的是声明您希望该变量以以下名称命名的名称：

bamboo_agent_capabilities_it:
  capability: /foo/bar
  dir: bamboo_agent_install_dir

然后使用vars lookup获取该变量的值，例如：

bamboo_agent_capabilities: "{{ lookup('vars', item.bamboo_agent_capabilities.dir) }}{{ item.bamboo_agent_capabilities.capability }}" 

考虑到剧本：

- hosts: localhost
  gather_facts: no
  vars:
    bamboo_agents_it:
      - bamboo_agent_capabilities: "{{ bamboo_agent_capabilities_it }}"
    bamboo_agent_capabilities_it:
      capability: /foo/bar
      dir: bamboo_agent_install_dir

  tasks:
    - set_fact:
        bamboo_agent_install_dir: /path/to/dir

    - debug:
        msg: 
          bamboo_agent_capabilities: "{{ lookup('vars', item.bamboo_agent_capabilities.dir) }}{{ item.bamboo_agent_capabilities.capability }}" 
      loop: "{{ bamboo_agents_it }}"

这产生了：

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

TASK [set_fact] ****************************************************************************************************
ok: [localhost]

TASK [debug] *******************************************************************************************************
ok: [localhost] => (item={'bamboo_agent_capabilities': {'capability': '/foo/bar', 'dir': 'bamboo_agent_install_dir'}}) => 
  msg:
    bamboo_agent_capabilities: /path/to/dir/foo/bar

PLAY RECAP *********************************************************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0