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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304
｜
第
9
章
3.
确保配置存在
在前面的例子中，我们编写并自动生成了
8
个配
置。本例将部署这些配置，确保其存在于
所有设备中。
理解幂等性
。
在研究这个例子的过程中，注意其中的用词和短语，比如
配置
SNMP
和
确保
SNMP
配置存在
。传统的
Python
脚本在每次执行脚本时都要发送
SNMP
命令
。对
于
Ansible
，就像很多
DevOps
配置管理工具一样
，其所采用的配置管理方法是幂等的
（
idempotent
）
，这意味着只做必要的改动。在网络模块上下文中，各个模块都加入了智能
逻辑，确保配置命令仅在必要时才发送给设备，使其进入所需状态。
从宏观层面来看，模块为此总是先要收集设备的现有配置。你希望能够留在设备上的命令
会与设备当前状态（运行时配置）进行比对。仅在当前配置中没有所需命令时，才会将该
命令发送至设备。这种做法比较安全，因为模块会运行某个剧本
N
次，但只会向设备发送
一次命令。
这正是
Ansible
的
config
模块所做的。在默认情况下，该模块可以获得
show run
的结果，
仅当剧本中的命令不在
show run
的输出中时才将其发送至设备。
使用
cong
模块
。
下面来看看如何使用
eos_config
模块为
Arista EOS
设备部署
SNMP
配
置文件。
- name: PLAY 2 - ENSURE EOS SNMP CONFIGS ARE DEPLOYED
hosts: eos
connection: local
gather_facts: no
tasks:
- name: DEPLOY CONFIGS ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
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.