Executors are used by minion to execute module functions. Executors can be used to modify the functions behavior, do any pre-execution steps or execute in a specific way like sudo executor.

Executors could be passed as a list and they will be used one-by-one in the order. If an executor returns None the next one will be called. If an executor returns non-None the execution sequence is terminated and the returned value is used as a result. It's a way executor could control modules execution working as a filter. Note that executor could actually not execute the function but just do something else and return None like splay executor does. In this case some other executor have to be used as a final executor that will actually execute the function. See examples below.

Executors list could be passed by minion config file in the following way:

  - splay
  - direct_call
splaytime: 30

The same could be done by command line:

salt -t 40 --module-executors='[splay, direct_call]' --executor-opts='{splaytime: 30}' '*' test.ping

And the same command called via netapi will look like this:

curl -sSk https://localhost:8000 \
    -H 'Accept: application/x-yaml' \
    -H 'X-Auth-Token: 697adbdc8fe971d09ae4c2a3add7248859c87079' \
    -H 'Content-type: application/json' \
    -d '[{
        "client": "local",
        "tgt": "*",
        "fun": "test.ping",
        "module_executors": ["splay", "direct_call"],
        "executor_opts": {"splaytime": 10}

Writing Salt Executors

A Salt executor is written in a similar manner to a Salt execution module. Executor is a python module placed into the executors folder and containing the execute function with the following signature:

def execute(opts, data, func, args, kwargs)

Where the args are:

Dictionary containing the minion configuration options
Dictionary containing the load data including executor_opts passed via cmdline/API.
func, args, kwargs:
Execution module function to be executed and it's arguments. For instance the simplest direct_call executor just runs it as func(*args, **kwargs).
None if the execution sequence must be continued with the next executor. Error string or execution result if the job is done and execution must be stopped.

Specific options could be passed to the executor via minion config or via executor_opts argument. For instance to access splaytime option set by minion config executor should access opts.get('splaytime'). To access the option set by commandline or API data.get('executor_opts', {}).get('splaytime') should be used. So if an option is safe and must be accessible by user executor should check it in both places, but if an option is unsafe it should be read from the only config ignoring the passed request data.

There is also a function named all_missing_func which the name of the func is passed, which can be used to verify if the command should still be run, even if it is not loaded in minion_mods.