Add custom how-to guides to documentation, additional notebook around how to use dev cli

docs/source/how_to_guides/custom_software.rst

@@ -0,0 +1,78 @@
+.. only:: comment
+
+    © Crown-owned copyright 2025, Defence Science and Technology Laboratory UK
+
+Creating Custom Software for PrimAITE
+*************************************
+
+This page aims to provide a how-to guide on how to create your own custom software for use within PrimAITE.
+
+PrimAITE has a base software class which should be inherited from when building custom software. Examples of this can be seen in the ``IOSoftware`` and ``Process`` classes.
+It's important that any new software created within PrimAITE has the ``identifier`` attribute defined, for use when generating the environment.
+
+Some default attributes may need to be adjusted to align with the intended application of the custom software.
+
+
+.. code:: Python
+
+    from src.primaite.simulator.system.software import Software
+
+    class CustomSoftware(Software, identifier="CustomSoftware"):
+        """
+        An example of Custom Software within PrimAITE.
+        """
+
+        operating_state: OperatingState
+        "The current operating state of the Custom software"
+
+        def describe_state(self) -> Dict:
+            """
+            Produce a dictionary describing the current state of this object.
+
+            :return: Current state of this object and child objects.
+            :rtype: Dict
+            """
+            state = super().describe_state()
+            state.update({"operating_state": self.operating_state.value})
+
+Default Install
+###############
+
+Software can be set to auto-install onto a Node by adding it to the ``SYSTEM_SOFTWARE`` dictionary for the node. An example can be seen in the ``HostNode`` class, which pre-installs some key software that is expected on Nodes, such as the ``NTPClient`` and ``UserManager``.
+
+Requirements
+############
+
+Any custom software will need to provide an implementation of the ``describe_state`` method, and conform to the general Pydantic requirements.
+It's a good idea, if possible, to also create a ``.show()`` method, as this can be used for visualising the software's status when developing within PrimAITE.
+
+Interaction with the PrimAITE Request System
+############################################
+
+If the software is intended to be used by an agent via a :ref:`custom_action`, then it will likely need an implementation of the ``RequestManager``.
+Detailed information about the PrimAITE request system can be seen in :ref:`request_system`. An example implementation, derived from the `Application` class is seen below:
+
+.. code:: Python
+
+    def _init_request_manager(self) -> RequestManager:
+        """
+        Initialise the request manager.
+
+        More information in user guide and docstring for SimComponent._init_request_manager.
+        """
+        _is_application_running = Application._StateValidator(application=self, state=ApplicationOperatingState.RUNNING)
+
+        rm = super()._init_request_manager()
+        rm.add_request(
+            "scan",
+            RequestType(
+                func=lambda request, context: RequestResponse.from_bool(self.scan()), validator=_is_application_running
+            ),
+        )
+        return rm
+
+
+Further information
+###################
+
+For more detailed information about the implementation of software within PrimAITE, see :ref:`software`.