[AQUA][STMD]Updated logic to deploy single ft model

ads/aqua/modeldeployment/deployment.py

@@ -242,7 +242,9 @@ def create(
                 model = create_deployment_details.models[0]
             else:
                 try:
-                    create_deployment_details.validate_base_model(model_id=model)
+                    model = create_deployment_details.validate_base_model(
+                        model_id=model
+                    )
                 except ConfigValidationError as err:
                     raise AquaValueError(f"{err}") from err
 

ads/aqua/modeldeployment/entities.py

@@ -8,9 +8,10 @@
 from pydantic import BaseModel, Field, model_validator
 
 from ads.aqua import logger
-from ads.aqua.common.entities import AquaMultiModelRef
+from ads.aqua.common.entities import AquaMultiModelRef, LoraModuleSpec
 from ads.aqua.common.enums import Tags
 from ads.aqua.common.errors import AquaValueError
+from ads.aqua.common.utils import is_valid_ocid
 from ads.aqua.config.utils.serializer import Serializable
 from ads.aqua.constants import (
     AQUA_FINE_TUNE_MODEL_VERSION,
@@ -717,34 +718,65 @@ def validate_ft_model_v2(
                     f"Invalid fine-tuned model ID '{base_model.id}': for fine tuned models like Phi4, the deployment is not supported. "
                 )
 
-    def validate_base_model(self, model_id: str) -> None:
+    def validate_base_model(self, model_id: str) -> Union[str, AquaMultiModelRef]:
         """
         Validates the input base model for single model deployment configuration.
 
         Validation Criteria:
-        - Fine-tuned models are not supported in single model deployment.
+        - Legacy fine-tuned models will be deployed as single model deployment.
+        - Fine-tuned models v2 will be deployed as stacked deployment.
 
         Parameters
         ----------
         model_id : str
             The OCID of DataScienceModel instance.
 
+        Returns
+        -------
+        Union[str, AquaMultiModelRef]
+            A string of model id or an instance of AquaMultiModelRef.
+
         Raises
         ------
         ConfigValidationError
             If any of the above conditions are violated.
         """
         base_model = DataScienceModel.from_id(model_id)
-        if Tags.AQUA_FINE_TUNED_MODEL_TAG in base_model.freeform_tags:
-            logger.error(
-                "Validation failed: Fine-tuned model ID '%s' is not supported for single-model deployment.",
-                base_model.id,
-            )
-            raise ConfigValidationError(
-                f"Invalid base model ID '{base_model.id}': "
-                "single-model deployment does not support fine-tuned models. "
-                f"Please deploy the fine-tuned model '{base_model.id}' as a stacked model deployment instead."
+        freeform_tags = base_model.freeform_tags
+        aqua_fine_tuned_model = freeform_tags.get(
+            Tags.AQUA_FINE_TUNED_MODEL_TAG, UNKNOWN
+        )
+        if aqua_fine_tuned_model:
+            fine_tuned_model_version = freeform_tags.get(
+                Tags.AQUA_FINE_TUNE_MODEL_VERSION, UNKNOWN
             )
+            # TODO: revisit to block deploying single fine tuned model after AQUA UI is integrated.
+            if fine_tuned_model_version.lower() == AQUA_FINE_TUNE_MODEL_VERSION:
+                # extracts base model id from tag 'aqua_fine_tuned_model' and builds AquaMultiModelRef instance for stacked deployment.
+                logger.debug(
+                    f"Detected base model is fine-tuned model {AQUA_FINE_TUNE_MODEL_VERSION} and switched to stack deployment."
+                )
+                segments = aqua_fine_tuned_model.split("#")
+                if not segments or not is_valid_ocid(segments[0]):
+                    logger.error(
+                        "Validation failed: Fine-tuned model ID '%s' is not supported for model deployment.",
+                        base_model.id,
+                    )
+                    raise ConfigValidationError(
+                        f"Invalid fine-tuned model ID '{base_model.id}': missing or invalid tag '{Tags.AQUA_FINE_TUNED_MODEL_TAG}' format. "
+                        f"Make sure tag '{Tags.AQUA_FINE_TUNED_MODEL_TAG}' is added with format <service_model_id>#<service_model_name>."
+                    )
+                # reset the model_id and models in create_model_deployment_details for stack deployment
+                self.model_id = None
+                self.models = [
+                    AquaMultiModelRef(
+                        model_id=segments[0],
+                        fine_tune_weights=[LoraModuleSpec(model_id=base_model.id)],
+                    )
+                ]
+                return self.models[0]
+
+        return model_id
 
     class Config:
         extra = "allow"

tests/unitary/with_extras/aqua/test_deployment.py

@@ -1539,7 +1539,7 @@ def test_create_deployment_for_foundation_model(
 
         mock_validate_base_model.assert_called()
         mock_create.assert_called_with(
-            model=TestDataset.MODEL_ID,
+            model=mock_validate_base_model.return_value,
             compartment_id=TestDataset.USER_COMPARTMENT_ID,
             project_id=TestDataset.USER_PROJECT_ID,
             freeform_tags=freeform_tags,
@@ -1640,7 +1640,7 @@ def test_create_deployment_for_fine_tuned_model(
 
         mock_validate_base_model.assert_called()
         mock_create.assert_called_with(
-            model=TestDataset.MODEL_ID,
+            model=mock_validate_base_model.return_value,
             compartment_id=TestDataset.USER_COMPARTMENT_ID,
             project_id=TestDataset.USER_PROJECT_ID,
             freeform_tags=None,
@@ -1741,7 +1741,7 @@ def test_create_deployment_for_gguf_model(
 
         mock_validate_base_model.assert_called()
         mock_create.assert_called_with(
-            model=TestDataset.MODEL_ID,
+            model=mock_validate_base_model.return_value,
             compartment_id=TestDataset.USER_COMPARTMENT_ID,
             project_id=TestDataset.USER_PROJECT_ID,
             freeform_tags=None,
@@ -1849,7 +1849,7 @@ def test_create_deployment_for_tei_byoc_embedding_model(
 
         mock_validate_base_model.assert_called()
         mock_create.assert_called_with(
-            model=TestDataset.MODEL_ID,
+            model=mock_validate_base_model.return_value,
             compartment_id=TestDataset.USER_COMPARTMENT_ID,
             project_id=TestDataset.USER_PROJECT_ID,
             freeform_tags=None,