Targeting Minions

Targeting minions is specifying which minions should run a command or execute a state by matching against hostnames, or system information, or defined groups, or even combinations thereof.

For example the command salt web1 apache.signal restart to restart the Apache httpd server specifies the machine web1 as the target and the command will only be run on that one minion.

Similarly when using States, the following top file specifies that only the web1 minion should execute the contents of webserver.sls:

    - webserver

The simple target specifications, glob, regex, and list will cover many use cases, and for some will cover all use cases, but more powerful options exist.

Targeting with Grains

The Grains interface was built into Salt to allow minions to be targeted by system properties. So minions running on a particular operating system can be called to execute a function, or a specific kernel.

Calling via a grain is done by passing the -G option to salt, specifying a grain and a glob expression to match the value of the grain. The syntax for the target is the grain key followed by a globexpression: "os:Arch*".

salt -G 'os:Fedora'

Will return True from all of the minions running Fedora.

To discover what grains are available and what the values are, execute the grains.item salt function:

salt '*' grains.items

more info on using targeting with grains can be found here.

Targeting with Executions

As of 0.8.8 targeting with executions is still under heavy development and this documentation is written to reference the behavior of execution matching in the future.

Execution matching allows for a primary function to be executed, and then based on the return of the primary function the main function is executed.

Execution matching allows for matching minions based on any arbitrary running data on the minions.

Compound Targeting

0.9.5 新版功能.

Multiple target interfaces can be used in conjunction to determine the command targets. These targets can then be combined using and or or statements. This is well defined with an example:

salt -C 'G@os:Debian and webser* or E@db.*'

In this example any minion who's id starts with webser and is running Debian, or any minion who's id starts with db will be matched.

The type of matcher defaults to glob, but can be specified with the corresponding letter followed by the @ symbol. In the above example a grain is used with G@ as well as a regular expression with E@. The webser* target does not need to be prefaced with a target type specifier because it is a glob.

more info on using compound targeting can be found here.

Node Group Targeting

0.9.5 新版功能.

For certain cases, it can be convenient to have a predefined group of minions on which to execute commands. This can be accomplished using what are called nodegroups. Nodegroups allow for predefined compound targets to be declared in the master configuration file, as a sort of shorthand for having to type out complicated compound expressions.

  group1: ',, and bl*'
  group2: 'G@os:Debian and'
  group3: 'G@os:Debian and N@group1'

There are many ways to target individual minions or groups of minions in Salt: