条件角色包含在Ansible中失败 [英] Conditional role inclusion fails in Ansible

问题描述

我想有条件地运行Ansible角色，即仅当不存在某些二进制文件时(对我而言，这意味着缺少某些特定的应用程序安装).

I want to run an Ansible role conditionally, i.e. only when some binary does NOT exist (which for me implies absence of some particular app installation).

类似于此处使用的模式.

在我的剧本中使用以下代码:

Using the following code in my playbook:

  - hosts: my_host

    tasks:
      - name: check app existence
        command: /opt/my_app/somebinary
        register: myapp_exists
        ignore_errors: yes

    roles:
      - { role: myconditional_role, when: myapp_exists|failed }
      - another_role_to_be_included_either_way

以下是输出:

PLAY ***************************************************************************

TASK [setup] *******************************************************************
ok: [my_host ]

TASK [ myconditional_role : create temporary installation directory] ***********************
fatal: [my_host]: FAILED! => {"failed": true, "msg": "ERROR! The conditional check 'myapp_exists|failed' failed. The error was: ERROR! |failed expects a dictionary"}

为什么条件检查失败?

在Ubuntu 16.04.01上使用ansible 2.0.0.2

btw:创建临时安装目录"是有条件包含角色的第一个主要任务的名称.

btw: "create temporary installation directory" is the name of the first main task of the conditionally included role.

推荐答案

任务是在角色之后执行的，因此myapp_exists是不确定的.
改为使用pre_tasks.

Tasks are executed after roles, so myapp_exists is undefined.
Use pre_tasks instead.

还请记住，when实际上不是有条件的角色，它只是将此when语句附加到您角色中的每个任务上.

Also keep in mind that when is not actually a conditional role, it just attaches this when statement to every task in your role.

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