feat: Support langchain transformer on fabric (#2036)

* support langchain transformer on fabric

* avoid addtional param

* format code

---------

Co-authored-by: cruise <cruiseli@microsoft.com>

cognitive/src/main/python/synapse/ml/cognitive/langchain/LangchainTransform.py

@@ -44,6 +44,7 @@ from pyspark.ml.util import (
 )
 from pyspark.sql.functions import udf
 from typing import cast, Optional, TypeVar, Type
+from synapse.ml.core.platform import running_on_synapse_internal
 
 OPENAI_API_VERSION = "2022-12-01"
 RL = TypeVar("RL", bound="MLReadable")
@@ -125,6 +126,14 @@ class LangchainTransformer(
         self.subscriptionKey = Param(self, "subscriptionKey", "openai api key")
         self.url = Param(self, "url", "openai api base")
         self.apiVersion = Param(self, "apiVersion", "openai api version")
+        self.running_on_synapse_internal = running_on_synapse_internal()
+        if running_on_synapse_internal():
+            from synapse.ml.fabric.service_discovery import get_fabric_env_config
+
+            self._setDefault(
+                url=get_fabric_env_config().fabric_env_config.ml_workload_endpoint
+                + "cognitive/openai"
+            )
         kwargs = self._input_kwargs
         if subscriptionKey:
             kwargs["subscriptionKey"] = subscriptionKey
@@ -196,10 +205,15 @@ class LangchainTransformer(
         def udfFunction(x):
             import openai
 
-            openai.api_type = "azure"
-            openai.api_key = self.getSubscriptionKey()
-            openai.api_base = self.getUrl()
-            openai.api_version = self.getApiVersion()
+            if self.running_on_synapse_internal and not self.isSet(self.url):
+                from synapse.ml.fabric.prerun.openai_prerun import OpenAIPrerun
+
+                OpenAIPrerun(api_base=self.getUrl()).init_personalized_session(None)
+            else:
+                openai.api_type = "azure"
+                openai.api_key = self.getSubscriptionKey()
+                openai.api_base = self.getUrl()
+                openai.api_version = self.getApiVersion()
             return self.getChain().run(x)
 
         outCol = self.getOutputCol()