How to Use the require and watch syntax in saltstack

Requisites

Require

Require_in

Watch

Watch_in

Conclusion)

Many powerful options are supported in the saltstack configuration relational system. Whether it is a simple installation of software packages or the use of templates and conditional statements. saltstack states can gradually become very complex from small to small. Fortunately, saltstack provides a method for solving the dependency between States. This section describes how to use require, require_in, watch, and watch_in.

Requisites

In the world of saltstack, there are two types of requisites (the Translator's note: This word does not find a proper Chinese translation and the original English word is used for the time being): requisites and "requisite_ins ". These requisites are ctional, used to specify that "I depend on something" or "something depends on me"

Require

The following example uses the require Syntax:

VIM:

PKG. Installed

/Etc/vimrc:

File. managed:

-Source: salt: // edit/vimrc

-Require:

-PKG: Vim

In this example, the/etc/vimrc file is not placed (managed) until the vim package is installed.

Require_in

The following is the same example, but require_in is used this time:

VIM:

PKG. installed:

-Require_in:

-File:/etc/vimrc

/Etc/vimrc:

File. managed:

-Source: salt: // edit/vimrc

In this example, the effect is the same. In vim, the/etc/vimrc depends on me.

At the end, a dependency map is created and executed in a finite (finite) and foreseeable (predictable) Order.

Watch

The following uses the watch syntax as an example. In this example, the running ntpd service will pay attention to/etc/NTP. if the conf file changes, the service will be restarted.

NTPD:

Service. Running:

-Watch:

-File:/etc/NTP. conf

/Etc/NTP. conf:

File. managed:

-Source: salt: // NTP/files/NTP. conf

Watch_in

In the following example, the/etc/NTP. conf Declaration (declaring) should be watched by the ntpd service

NTPD:

Service. Running

/Etc/NTP. conf:

File. managed:

-Source: salt: // NTP/files/NTP. conf

-Watch_in:

-Service: NTPD

Conclusion)

In the state rule, you can specify the dependency between States through powerful require, require_in, watch, and watch_in. whether a service should watch a file change, or make sure that the software package has been installed before a service runs, they can be used to specify the logic execution sequence of state.

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How to Use the require and watch syntax in saltstack