feat: Initial template for Langchain on Vertex.

PiperOrigin-RevId: 622468677

Author: yeesian

setup.py

@@ -150,6 +150,12 @@
     "pandas >= 1.0.0, < 2.2.0",
 ]
 
+langchain_extra_require = [
+    "langchain >= 0.1.13, < 0.2",
+    "langchain-core < 0.2",
+    "langchain-google-vertexai < 0.2",
+]
+
 full_extra_require = list(
     set(
         tensorboard_extra_require
@@ -253,6 +259,7 @@
         "ray_testing": ray_testing_extra_require,
         "reasoningengine": reasoning_engine_extra_require,
         "rapid_evaluation": rapid_evaluation_extra_require,
+        "langchain": langchain_extra_require,
     },
     python_requires=">=3.8",
     classifiers=[

vertexai/preview/reasoning_engines.py vertexai/preview/reasoning_engines/__init__.py

@@ -20,8 +20,12 @@
     Queryable,
     ReasoningEngine,
 )
+from vertexai.preview.reasoning_engines.templates.langchain import (
+    LangchainAgent
+)
 
 __all__ = (
+    "LangchainAgent",
     "Queryable",
     "ReasoningEngine",
 )