Salt can be controlled by a command line client by the root user on the Salt master. The Salt command line client uses the Salt client API to communicate with the Salt master server. The Salt client is straightforward and simple to use.
Using the Salt client commands can be easily sent to the minions.
Each of these commands accepts an explicit --config option to point to either the master or minion configuration file. If this option is not provided and the default configuration file does not exist then Salt falls back to use the environment variables SALT_MASTER_CONFIG and SALT_MINION_CONFIG.
See also
The Salt command needs a few components to send information to the Salt minions. The target minions need to be defined, the function to call and any arguments the function requires.
The first argument passed to salt, defines the target minions, the target minions are accessed via their hostname. The default target type is a bash glob:
salt \*foo.com sys.doc
Salt can also define the target minions with regular expressions:
salt -E '.*' cmd.run 'ls -l | grep foo'
Or to explicitly list hosts, salt can take a list:
salt -L foo.bar.baz,quo.qux cmd.run 'ps aux | grep foo'
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.
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 regular expression to match the value of the grain.
salt -G 'os:Fedora' test.ping
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
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.
New in version 0.9.5.
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.*' test.ping
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.
New in version 0.9.5.
Often the convenience of having a predefined group of minions to execute targets on is desired. This can be accomplished with the new nodegroups feature. Nodegroups allow for predefined compound targets to be declared in the master configuration file:
nodegroups:
group1: '[email protected],bar.domain.com,baz.domain.com and bl*.domain.com'
group2: 'G@os:Debian and foo.domain.com'
The function to call on the specified target is placed after the target specification.
New in version 0.9.8.
Functions may also accept arguments, space-delimited:
salt '*' cmd.exec_code python 'import sys; print sys.version'
Optional, keyword arguments are also supported:
salt '*' pip.install salt timeout=5 upgrade=True
They are always in the form of kwarg=argument.
The Salt functions are self documenting, all of the function documentation can be retried from the minions via the sys.doc() function:
salt '*' sys.doc
If a series of commands needs to be sent to a single target specification then the commands can be sent in a single publish. This can make gathering groups of information faster, and lowers the stress on the network for repeated commands.
Compound command execution works by sending a list of functions and arguments instead of sending a single function and argument. The functions are executed on the minion in the order they are defined on the command line, and then the data from all of the commands are returned in a dictionary. This means that the set of commands are called in a predictable way, and the returned data can be easily interpreted.
Executing compound commands if done by passing a comma delimited list of functions, followed by a comma delimited list of arguments:
salt '*' cmd.run,test.ping,test.echo 'cat /proc/cpuinfo',,foo
The trick to look out for here, is that if a function is being passed no arguments, then there needs to be a placeholder for the absent arguments. This is why in the above example, there are two commas right next to each other. test.ping takes no arguments, so we need to add another comma, otherwise Salt would attempt to pass "foo" to test.ping.