fix: Add code_dir to sys.path in HandlerService for MME (#73)

This addresses an issue with environment variables not being inherited from the shell environment when using miniconda.

Author: giuseppeporcelli

src/sagemaker_pytorch_serving_container/handler_service.py

@@ -17,8 +17,14 @@
 from sagemaker_pytorch_serving_container.default_inference_handler import \
     DefaultPytorchInferenceHandler
 
+import os
+import sys
+
+ENABLE_MULTI_MODEL = os.getenv("SAGEMAKER_MULTI_MODEL", "false") == "true"
+
 
 class HandlerService(DefaultHandlerService):
+
     """Handler service that is executed by the model server.
 
     Determines specific default inference handlers to use based on the type MXNet model being used.
@@ -31,5 +37,16 @@ class HandlerService(DefaultHandlerService):
 
     """
     def __init__(self):
+        self._initialized = False
+
         transformer = Transformer(default_inference_handler=DefaultPytorchInferenceHandler())
         super(HandlerService, self).__init__(transformer=transformer)
+
+    def initialize(self, context):
+        # Adding the 'code' directory path to sys.path to allow importing user modules when multi-model mode is enabled.
+        if (not self._initialized) and ENABLE_MULTI_MODEL:
+            code_dir = os.path.join(context.system_properties.get("model_dir"), 'code')
+            sys.path.append(code_dir)
+            self._initialized = True
+
+        super().initialize(context)