The Init Function

If config.py contains an init function, it is called during LLMRails initialization. Use it to set up shared resources and register action parameters.

Basic Usage

from nemoguardrails import LLMRails

def init(app: LLMRails):
    # Initialize database connection
    db = DatabaseConnection()

    # Register as action parameter (available to all actions)
    app.register_action_param("db", db)

Registering Action Parameters

Action parameters registered in config.py are automatically injected into actions that declare them:

config.py:

from nemoguardrails import LLMRails

def init(app: LLMRails):
    # Initialize shared resources
    db = DatabaseConnection(host="localhost", port=5432)
    api_client = ExternalAPIClient(api_key="...")

    # Register as action parameters
    app.register_action_param("db", db)
    app.register_action_param("api_client", api_client)

actions.py:

from nemoguardrails.actions import action

@action()
async def fetch_user_data(user_id: str, db=None):
    """The 'db' parameter is injected from config.py."""
    return await db.get_user(user_id)

@action()
async def call_external_service(query: str, api_client=None):
    """The 'api_client' parameter is injected from config.py."""
    return await api_client.search(query)

Accessing the Configuration

The app parameter provides access to the full configuration:

def init(app: LLMRails):
    # Access the RailsConfig object
    config = app.config

    # Access custom data from config.yml
    custom_settings = config.custom_data

    # Access model configurations
    models = config.models

Example: Database Connection

import asyncpg
from nemoguardrails import LLMRails

async def create_db_pool():
    return await asyncpg.create_pool(
        host="localhost",
        database="mydb",
        user="user",
        password="password"
    )

def init(app: LLMRails):
    import asyncio

    # Create connection pool
    loop = asyncio.get_event_loop()
    db_pool = loop.run_until_complete(create_db_pool())

    # Register for use in actions
    app.register_action_param("db_pool", db_pool)

Example: API Client Initialization

import httpx
from nemoguardrails import LLMRails

def init(app: LLMRails):
    # Get API key from custom_data in config.yml
    api_key = app.config.custom_data.get("api_key")

    # Create HTTP client with authentication
    client = httpx.AsyncClient(
        base_url="https://api.example.com",
        headers={"Authorization": f"Bearer {api_key}"}
    )

    app.register_action_param("http_client", client)