January 2023
Intermediate to advanced
458 pages
14h 16m
Chinese
Content preview from 可编程网络自动化
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154
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第
6
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# 在声明之后，过滤器会被加入ENV对象中。bracket_expansion是我们传入的函数，
# 在渲染模板时，模板引擎会执行此函数
ENV.filters['bracket_expansion'] = bracket_expansion
template = ENV.get_template("template.j2")
# 作为过滤器传入的bracket_expansion函数需要一个文本模式才能工作，让我们
# 将其作为iface_pattern传入
print
(template.render(iface_pattern='GigabitEthernet0/0/[0-3]'))
这是一个非常强大的工具——你完全可以编写自己的
Python
函数来将其提升到一个更高的
水平。可以尝试一下其他的文本操作函数和库，或者自己编写。
6.3.6
Jinja
模板继承
在为网络配置创建规模更大、功能更强的模板时，你可能想把模板分解为更小、更具体的
部分。一个模板用于
VLAN
配置
，一个模板用于接口，可能还有一个模板用于路由协议，
这都是很常见的情况。尽管不是必需的，但这种组织工具可以提供更大的灵活性。问题在
于该如何以有意义的方式将这些模板彼此联系起来以形成一套完整的配置呢？
Jinja
允许在模板文件中执行继承
，这是解决上述问题的简便方法。例如，
vlans.j2
文件只
包含
VLAN
配置
，你可以在另一个模板文件中继承该文件来生成
VLAN
配置。也可以自
己编写接口配置模板，其中的
VLAN ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.