feat: add SoftwareSystemInstances to DeploymentNodes

Author: yt-ms

src/structurizr/model/deployment_node.py

@@ -23,6 +23,7 @@
 from .container_instance import ContainerInstance, ContainerInstanceIO
 from .deployment_element import DeploymentElement, DeploymentElementIO
 from .infrastructure_node import InfrastructureNode, InfrastructureNodeIO
+from .software_system import SoftwareSystem
 from .software_system_instance import SoftwareSystemInstance, SoftwareSystemInstanceIO
 
 
@@ -169,6 +170,37 @@ def add_container_instance(
         model += instance
         return instance
 
+    def add_software_system_instance(
+        self, software_system: SoftwareSystem, *, replicate_relationships: bool
+    ) -> SoftwareSystemInstance:
+        """
+        Create a new instance of the given software system.
+
+        Args:
+            software_system(SoftwareSystem): the SoftwareSystem to add an instance of.
+            replicate_relationships: True if relationships should be replicated between
+                                     the element instances in the same deployment
+                                     environment, False otherwise.
+        """
+        instance_id = (
+            max(
+                [
+                    s.instance_id
+                    for s in self.software_system_instances
+                    if s.software_system is software_system
+                ],
+                default=0,
+            )
+            + 1
+        )
+        instance = SoftwareSystemInstance(
+            software_system=software_system, instance_id=instance_id, parent=self
+        )
+        self._software_system_instances.add(instance)
+        model = self.model
+        model += instance
+        return instance
+
     def __iadd__(self, node: "DeploymentNode") -> "DeploymentNode":
         """Add a newly constructed chile deployment node to this node."""
         if node in self._children:
@@ -217,4 +249,10 @@ def hydrate(
             instance = ContainerInstance.hydrate(instance_io, model=model, parent=node)
             node._container_instances.add(instance)
 
+        for instance_io in deployment_node_io.software_system_instances:
+            instance = SoftwareSystemInstance.hydrate(
+                instance_io, model=model, parent=node
+            )
+            node._software_system_instances.add(instance)
+
         return node

src/structurizr/model/software_system_instance.py

@@ -29,6 +29,7 @@
 
 
 if TYPE_CHECKING:
+    from .deployment_node import DeploymentNode
     from .model import Model
 
 
@@ -60,6 +61,7 @@ def hydrate(
         cls,
         system_instance_io: SoftwareSystemInstanceIO,
         model: "Model",
+        parent: "DeploymentNode",
     ) -> "SoftwareSystemInstance":
         """Hydrate a new SoftwareSystemInstance instance from its IO.
 
@@ -69,6 +71,7 @@ def hydrate(
         instance = cls(
             **cls.hydrate_arguments(system_instance_io),
             software_system=system,
+            parent=parent,
         )
         model += instance
         return instance

tests/unit/model/test_deployment_node.py

@@ -164,3 +164,46 @@ def test_deployment_node_serialising_container(model_with_node):
 def test_deployment_node_adding_container_replicating_relationships(model_with_node):
     """Test replicating relationships when adding a container instance."""
     raise AssertionError()  # Not implemented yet
+
+
+def test_deployment_node_add_software_system(model_with_node):
+    """Test adding a software system to a node to create an instance."""
+    node = model_with_node.empty_node
+    system = MockElement("element")
+
+    instance = node.add_software_system_instance(system, replicate_relationships=False)
+
+    assert instance.software_system is system
+    assert instance.model is model_with_node
+    assert instance.parent is node
+    assert instance in node.software_system_instances
+    assert instance.instance_id == 1
+
+
+def test_deployment_node_serialising_software_system(model_with_node):
+    """Test serialisation and deserialisation includes container instances."""
+    node = model_with_node.empty_node
+    system = model_with_node.mock_element
+    node.add_software_system_instance(system, replicate_relationships=False)
+
+    io = DeploymentNodeIO.from_orm(node)
+
+    assert len(io.software_system_instances) == 1
+    assert io.software_system_instances[0].id == "id"
+
+    node2 = DeploymentNode.hydrate(io, model_with_node)
+
+    assert len(node2.software_system_instances) == 1
+    instance = node2.software_system_instances[0]
+    assert instance.instance_id == 1
+    assert instance.software_system is system
+    assert instance.model is model_with_node
+    assert instance.parent is node2
+
+
+@pytest.mark.xfail(strict=True)
+def test_deployment_node_adding_software_system_replicating_relationships(
+    model_with_node,
+):
+    """Test replicating relationships when adding a software system instance."""
+    raise AssertionError()  # Not implemented yet

tests/unit/model/test_software_system_instance.py

@@ -94,7 +94,7 @@ def test_software_system_instance_hydration_retrieves_software_system_from_id(
         software_system_id="19", instance_id=3, environment="Live"
     )
 
-    instance = SoftwareSystemInstance.hydrate(io, model_with_system)
+    instance = SoftwareSystemInstance.hydrate(io, model_with_system, parent=None)
 
     assert instance.instance_id == 3
     assert instance.environment == "Live"
@@ -108,7 +108,7 @@ def test_software_system_instance_name_is_software_system_name(model_with_system
         software_system_id="19", instance_id=3, environment="Live"
     )
 
-    instance = SoftwareSystemInstance.hydrate(io, model_with_system)
+    instance = SoftwareSystemInstance.hydrate(io, model_with_system, parent=None)
 
     assert instance.name == "Mock System"
 
@@ -123,7 +123,7 @@ def test_software_system_instance_hyrdates_http_health_checks(model_with_system)
         health_checks=[health_check_io],
     )
 
-    instance = SoftwareSystemInstance.hydrate(io, model_with_system)
+    instance = SoftwareSystemInstance.hydrate(io, model_with_system, parent=None)
 
     assert len(instance.health_checks) == 1
     assert list(instance.health_checks)[0].name == "name"