Enhance robustness (#11)

src/turtle_agent/scripts/llm.py

@@ -23,17 +23,17 @@ def get_llm():
     """A helper function to get the LLM instance."""
     dotenv.load_dotenv(dotenv.find_dotenv())
 
-    APIM_SUBSCRIPTION_KEY = os.getenv("APIM_SUBSCRIPTION_KEY")
+    APIM_SUBSCRIPTION_KEY = get_env_variable("APIM_SUBSCRIPTION_KEY")
     default_headers = {}
-    if APIM_SUBSCRIPTION_KEY != None:
+    if APIM_SUBSCRIPTION_KEY is not None:
         # only set this if the APIM API requires a subscription...
         default_headers["Ocp-Apim-Subscription-Key"] = APIM_SUBSCRIPTION_KEY
 
     # Set up authority and credentials for Azure authentication
     credential = ClientSecretCredential(
-        tenant_id=os.getenv("AZURE_TENANT_ID"),
-        client_id=os.getenv("AZURE_CLIENT_ID"),
-        client_secret=os.getenv("AZURE_CLIENT_SECRET"),
+        tenant_id=get_env_variable("AZURE_TENANT_ID"),
+        client_id=get_env_variable("AZURE_CLIENT_ID"),
+        client_secret=get_env_variable("AZURE_CLIENT_SECRET"),
         authority="https://login.microsoftonline.com",
     )
 
@@ -42,12 +42,36 @@ def get_llm():
     )
 
     llm = AzureChatOpenAI(
-        azure_deployment=os.getenv("DEPLOYMENT_ID"),
+        azure_deployment=get_env_variable("DEPLOYMENT_ID"),
         azure_ad_token_provider=token_provider,
         openai_api_type="azure_ad",
-        api_version=os.getenv("API_VERSION"),
-        azure_endpoint=os.getenv("API_ENDPOINT"),
+        api_version=get_env_variable("API_VERSION"),
+        azure_endpoint=get_env_variable("API_ENDPOINT"),
         default_headers=default_headers,
     )
 
     return llm
+
+
+def get_env_variable(var_name):
+    """
+    Retrieves the value of the specified environment variable.
+
+    Args:
+        var_name (str): The name of the environment variable to retrieve.
+
+    Returns:
+        str: The value of the environment variable.
+
+    Raises:
+        ValueError: If the environment variable is not set.
+
+    This function provides a consistent and safe way to retrieve environment variables.
+    By using this function, we ensure that all required environment variables are present
+    before proceeding with any operations. If a variable is not set, the function will
+    raise a ValueError, making it easier to debug configuration issues.
+    """
+    value = os.getenv(var_name)
+    if value is None:
+        raise ValueError(f"Environment variable {var_name} is not set.")
+    return value