Update app.py

app.py

@@ -11,8 +11,13 @@ from langchain_core.prompts import PromptTemplate
 from langchain.schema.output_parser import StrOutputParser
 from langchain.schema.runnable import RunnablePassthrough
 from langchain.schema.runnable.config import RunnableConfig
+import logging
 
-# GLOBAL SCOPE - ENTIRE APPLICATION HAS ACCESS TO VALUES SET IN THIS SCOPE #
+# Set up logging
+logging.basicConfig(level=logging.INFO)
+logger = logging.getLogger(__name__)
+
+# Load environment variables
 load_dotenv()
 
 HF_LLM_ENDPOINT = os.environ["HF_LLM_ENDPOINT"]
@@ -27,13 +32,17 @@ hf_embeddings = HuggingFaceEndpointEmbeddings(
     huggingfacehub_api_token=HF_TOKEN,
 )
 
-vectorstore = FAISS.load_local(
-    vectorstore_path, 
-    hf_embeddings, 
-    allow_dangerous_deserialization=True
-)
-hf_retriever = vectorstore.as_retriever()
-print("Loaded Vectorstore")
+try:
+    vectorstore = FAISS.load_local(
+        vectorstore_path, 
+        hf_embeddings, 
+        allow_dangerous_deserialization=True
+    )
+    hf_retriever = vectorstore.as_retriever()
+    logger.info("Loaded Vectorstore")
+except Exception as e:
+    logger.error(f"Error loading Vectorstore: {e}")
+    raise
 
 RAG_PROMPT_TEMPLATE = """\
 system
@@ -48,15 +57,20 @@ assistant
 
 rag_prompt = PromptTemplate.from_template(RAG_PROMPT_TEMPLATE)
 
-hf_llm = HuggingFaceEndpoint(
-    endpoint_url=HF_LLM_ENDPOINT,
-    max_new_tokens=512,
-    top_k=10,
-    top_p=0.95,
-    temperature=0.1,
-    repetition_penalty=1.0,
-    huggingfacehub_api_token=HF_TOKEN,
-)
+try:
+    hf_llm = HuggingFaceEndpoint(
+        endpoint_url=HF_LLM_ENDPOINT,
+        max_new_tokens=512,
+        top_k=10,
+        top_p=0.95,
+        temperature=0.1,
+        repetition_penalty=1.0,
+        huggingfacehub_api_token=HF_TOKEN,
+    )
+    logger.info("Initialized HuggingFace LLM endpoint")
+except Exception as e:
+    logger.error(f"Error initializing HuggingFace LLM endpoint: {e}")
+    raise
 
 @cl.author_rename
 def rename(original_author: str):
@@ -73,14 +87,16 @@ async def start_chat():
             | rag_prompt | hf_llm
         )
         cl.user_session.set("lcel_rag_chain", lcel_rag_chain)
-    except KeyError as e:
-        print(f"Session error on start: {e}")
+        logger.info("Started chat and set LCEL RAG chain in user session")
+    except Exception as e:
+        logger.error(f"Error during chat start: {e}")
 
 @cl.on_message  
 async def main(message: cl.Message):
     try:
         lcel_rag_chain = cl.user_session.get("lcel_rag_chain")
         if lcel_rag_chain is None:
+            logger.warning("Session has expired. Asking user to restart the chat.")
             await cl.Message(content="Session has expired. Please restart the chat.").send()
             return
 
@@ -91,6 +107,10 @@ async def main(message: cl.Message):
         ):
             await msg.stream_token(chunk)
         await msg.send()
+        logger.info("Message processed successfully")
     except KeyError as e:
+        logger.error(f"Session error: {e}")
         await cl.Message(content="An error occurred. Please restart the chat.").send()
-        print(f"Session error: {e}")
+    except Exception as e:
+        logger.error(f"Unexpected error: {e}")
+        await cl.Message(content="An unexpected error occurred. Please try again.").send()