Salt is written to be completely API centric, Salt minions and master can be built directly into third party applications as a communication layer. The Salt client API is very straightforward.
A number of client command methods are available depending on the exact behavior desired.
Sending information through the client is simple:
# Import the Salt client library
import salt.client
# create a local client object
client = salt.client.LocalClient()
# make calls with the cmd method
ret = client.cmd('*', 'cmd.run', ['ls -l'])
The LocalClient object only works running as root on the salt-master, it is the same interface used by the salt command line tool.
The cmd method will execute and wait for the timeout period for all minions to reply, then it will return all minion data at once.
The tgt option is the target specification, by default a target is passed in as a bash shell glob. The expr_form option allows the tgt to be passed as either a PCRE regular expression or as a Python list.
The name of the function to call on the specified minions. The documentation for these functions can be seen by running on the salt-master: salt '*' sys.doc
The optional arg parameter is used to pass a list of options on to the remote function
The number of seconds to wait after the last minion returns but before all minions return.
The type of tgt that is passed in, the allowed values are:
Specify the returner to use. The value passed can be single returner, or a comma delimited list of returners to call in order on the minions
The cmd_cli method is used by the salt command, it is a generator. This method returns minion returns as the come back and attempts to block until all minions return.
The tgt option is the target specification, by default a target is passed in as a bash shell glob. The expr_form option allows the tgt to be passed as either a pcre regular expression or as a Python list.
The name of the function to call on the specified minions. The documentation for these functions can be seen by running on the salt-master: salt '*' sys.doc
The optional arg parameter is used to pass a list of options on to the remote function
The number of seconds to wait after the last minion returns but before all minions return.
The type of tgt that is passed in, the allowed values are:
Specify the returner to use. The value passed can be single returner, or a comma delimited list of returners to call in order on the minions
Print extra information about the running command to the terminal
The cmd_iter method is a generator which yields the individual minion returns as the come in.
The tgt option is the target specification, by default a target is passed in as a bash shell glob. The expr_form option allows the tgt to be passed as either a pcre regular expression or as a Python list.
The name of the function to call on the specified minions. The documentation for these functions can be seen by running on the salt-master: salt '*' sys.doc
The optional arg parameter is used to pass a list of options on to the remote function
The number of seconds to wait after the last minion returns but before all minions return.
The type of tgt that is passed in, the allowed values are:
Specify the returner to use. The value passed can be single returner, or a comma delimited list of returners to call in order on the minions
The cmd_iter method will block waiting for individual minions to return, the cmd_iter_no_block method will return None until the next minion returns. This allows for actions to be injected in between minion returns
The tgt option is the target specification, by default a target is passed in as a bash shell glob. The expr_form option allows the tgt to be passed as either a pcre regular expression or as a Python list.
The name of the function to call on the specified minions. The documentation for these functions can be seen by running on the salt-master: salt '*' sys.doc
The optional arg parameter is used to pass a list of options on to the remote function
The number of seconds to wait after the last minion returns but before all minions return.
The type of tgt that is passed in, the allowed values are:
Specify the returner to use. The value passed can be single returner, or a comma delimited list of returners to call in order on the minions
The Salt client API can also send what is called a compound command. Often a collection of commands need to be executed on the targeted minions, rather than send the commands one after another, they can be sent in a single publish containing a series of commands. This can dramatically lower overhead and speed up the application communicating with Salt.
When commands are executed with compound execution the minion functions called are executed in serial on the minion and the return value is sent back in a different fashion. The return value is a dict, with the function names as keys to the function returns as values.
Using the compound command execution system via the API requires that the fun value and the arg value are lists matching by index. This ensures that the order of the executions can be controlled. Any function that has no arguments MUST have an empty array in the corresponding arg index.
All client command methods can execute compound commands.
# Import the Salt client library
import salt.client
# create a local client object
client = salt.client.LocalClient()
# make compound execution calls with the cmd method
ret = client.cmd('*', ['cmd.run', 'test.ping', 'test.echo'], [['ls -l'], [], ['foo']])
This will execute cmd.run ls -l then test.ping and finally test.echo foo. The return data from the minion will look like this:
{'cmd.run': '<output from ls -l>',
'test.ping': True,
'test.echo': 'foo'}
The Salt minion caller api can be used to simplify the execution and use of minion elements. The caller api is useful for accessing the Salt api, direct access to the state functions, using the matcher interface on a single minion, and as an api for the peer interface. Using the api is fairly straightforward:
# Import the Salt client library
import salt.client
# Create the caller object
caller = salt.client.Caller()
# call a function
caller.function('test.ping')
# Call objects directly:
caller.sminion.functions['cmd.run']('ls -l')