当ansible查找失败时，如何退回到默认值? [英] How to fallback to a default value when ansible lookup fails?

问题描述

我很惊讶地发现他的代码因IOError异常而失败，而不是默认忽略该值.

I was a little bit surprised to discover that his piece of code fails with an IOError exception instead of defaulting to omitting the value.

#!/usr/bin/env ansible-playbook -i localhost,
---
- hosts: localhost
  tasks:
    - debug: msg="{{ lookup('ini', 'foo section=DEFAULT file=missing-file.conf') | default(omit) }}"

如何在不引发异常的情况下加载值?

How can I load a value without raising an exception?

请注意，查找模块支持默认值参数，但是这个对我来说是没有用的，因为它仅在可以打开文件时才起作用.

Please note that the lookup module supports a default value parameter but this one is useless to me because it works only when it can open the file.

我需要一个即使无法打开文件也可以使用的默认值.

I need a default value that works even when the it fails to open the file.

推荐答案

据我所知，Jinja2不支持任何try/catch机制.

As far as I know Jinja2 unfortunately doesn't support any try/catch mechanism.

因此，您可以将ini查找插件/文件问题修补到Ansible团队，或者使用此丑陋的解决方法:

So you either patch ini lookup plugin / file issue to Ansible team, or use this ugly workaround:

---
- hosts: localhost
  gather_facts: no
  tasks:
    - debug: msg="{{ lookup('first_found', dict(files=['test-ini.conf'], skip=true)) | ternary(lookup('ini', 'foo section=DEFAULT file=test-ini.conf'), omit) }}"

在此示例中，first_found查找返回文件名(如果文件存在)，否则返回空列表.如果文件存在，则ternary过滤器将调用ini查找，否则将返回omit占位符.

In this example first_found lookup return file name if file exists or empty list otherwise. If file exists, ternary filter calls ini lookup, otherwise omit placeholder is returned.

这篇关于当ansible查找失败时，如何退回到默认值?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！