.. _engines:

============ Salt Engines

.. versionadded:: 2015.8.0

Salt Engines are long-running, external system processes that leverage Salt.

• Engines have access to Salt configuration, execution modules, and runners (__opts__, __salt__, and __runners__).
• Engines are executed in a separate process that is monitored by Salt. If a Salt engine stops, it is restarted automatically.
• Engines can run on the Salt master and on Salt minions.

Salt engines enhance and replace the :ref:external processes <ext-processes> functionality.

Configuration

Salt engines are configured under an engines top-level section in your Salt master or Salt minion configuration. Provide a list of engines and parameters under this section.

.. code-block:: yaml

engines: - logstash: host: log.my_network.com port: 5959 proto: tcp

.. versionadded:: 3000

Multiple copies of a particular Salt engine can be configured by including the engine_module parameter in the engine configuration.

.. code-block:: yaml

engines: - production_logstash: host: production_log.my_network.com port: 5959 proto: tcp engine_module: logstash - develop_logstash: host: develop_log.my_network.com port: 5959 proto: tcp engine_module: logstash

Salt engines must be in the Salt path, or you can add the engines_dirs option in your Salt master configuration with a list of directories under which Salt attempts to find Salt engines. This option should be formatted as a list of directories to search, such as:

.. code-block:: yaml

engines_dirs:
  - /home/bob/engines

Writing an Engine

An example Salt engine, :blob:salt/engines/test.py, is available in the Salt source. To develop an engine, the only requirement is that your module implement the start() function.