Note
Salt beacons are an event generation mechanism. Beacons leverage the Salt reactor system to make changes when beacon events occur.
Salt beacons是一种事件生成机制。beacons事件发生时，beacons利用Salt反应堆系统进行更改。

1 beacons:
2   inotify:
3     - files:
4         /etc/important_file: {}
5         /opt: {}

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Note
The inotify beacon only works on OSes that have inotify kernel support. Currently this excludes FreeBSD, macOS, and Windows.
inotify beacon只适用于具有inotify内核支持的操作系统。 目前这不包括FreeBSD，macOS和Windows。

important_config: True

add beacon configs to minion

On the Salt minion, add the following configuration to /etc/salt/minion.d/beacons.conf:

在Salt minion上，将以下配置添加到/etc/salt/minion.d/beacons.conf中：

1 beacons:
2   inotify:
3     - files:
4         /etc/important_file:
5           mask:
6             - modify
7     - disable_during_state_run: True

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Save the configuration file and restart the minion service. The beacon is now set up to notify salt upon modifications made to the file.

保存配置文件并重新启动minion的服务。beacon现在设置为在对文件进行修改时通知salt。

Note
The disable_during_state_run: True parameter prevents the inotify beacon from generating reactor events due to salt itself modifying the file.
disable_during_state_run：True参数可以防止inotify beacon生成反应器事件，因为salt本身会修改文件。

view events on the master

On your Salt master, start the event runner using the following command:

在你的Salt master上，使用以下命令启动事件执行器：

salt-run state.event pretty=true

This runner displays events as they are received by the master on the Salt event bus. To test the beacon you set up in the previous section, make and save a modification to /etc/important_file. You'll see an event similar to the following on the event bus:

这个执行在Salt事件总线上由maser接收时显示事件。 要测试您在前一节中设置的beacon，请对/etc/important_file进行修改并保存。 您将在事件总线上看到与以下内容类似的事件：

1 {
2  "_stamp": "2015-09-09T15:59:37.972753",
3  "data": {
4      "change": "IN_IGNORED",
5      "id": "larry",
6      "path": "/etc/important_file"
7  },
8  "tag": "salt/beacon/larry/inotify//etc/important_file"
9 }

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This indicates that the event is being captured and sent correctly. Now you can create a reactor to take action when this event occurs.

这表示事件正在被捕获并正确发送。 现在，您可以创建一个反应堆，在发生此事件时采取行动。

create a reactor

This reactor reverts the file named /etc/important_file to the contents provided by salt each time it is modified.

该反应器在每次修改时将名为/etc/important_file的文件恢复为salt提供的内容。

reactor sls

On your Salt master, create a file named /srv/reactor/revert.sls.

在Salt master端，创建一个名为/srv/reactor/revert.sls.

Note
If the /srv/reactor directory doesn't exist, create it.

mkdir -p /srv/reactor

Add the following to /srv/reactor/revert.sls:

1 revert-file:
2   local.state.apply:
3     - tgt: {{ data['data']['id'] }}
4     - arg:
5       - maintain_important_file

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Note
In addition to setting disable_during_state_run: True for an inotify beacon whose reaction is to modify the watched file, it is important to ensure the state applied is also idempotent.
除了设置disable_during_state_run：True对于反应修改观察文件的inotify beacon而言，重要的是要确保所应用的状态也是幂等的。
Note
The expression {{ data['data']['id'] }} is correct as it matches the event structure shown above.
表达式{{data ['data'] ['id']}}是正确的，因为它匹配上面显示的事件结构。