Implementation:Protectai Llm guard Create app

Knowledge Sources	LLM Guard
Domains	API_Design, Web_Development, DevOps
Last Updated	2026-02-14 12:00 GMT

Overview

Concrete tool for constructing the LLM Guard FastAPI application with all middleware, routes, and scanners configured, provided by the LLM Guard API server.

Description

The create_app function is the FastAPI application factory. It loads configuration from a YAML file (path from CONFIG_FILE env var), initializes scanner pipelines, configures authentication, rate limiting, CORS middleware, OpenTelemetry instrumentation, and registers all scanning API routes.

Usage

Called by Uvicorn at server startup. Not typically imported by end users directly.

Code Reference

Source Location

Repository: llm-guard
File: llm_guard_api/app/app.py
Lines: L57-88

Signature

def create_app() -> FastAPI:
    """
    Create and configure the LLM Guard FastAPI application.

    Reads CONFIG_FILE env var (default: ./config/scanners.yml).
    Initializes scanners, middleware, routes, and observability.

    Returns:
        Fully configured FastAPI application instance.
    """

Import

from llm_guard_api.app.app import create_app

I/O Contract

Inputs

Name	Type	Required	Description
CONFIG_FILE (env var)	str	No	Path to YAML config (default: ./config/scanners.yml)

Outputs

Name	Type	Description
app	FastAPI	Fully configured FastAPI application with routes and middleware

Usage Examples

Uvicorn Startup

# Start the API server
uvicorn app.app:create_app --host=0.0.0.0 --port=8000 --workers=4

Docker Compose

services:
  llm_guard_api:
    build: .
    ports:
      - "8000:8000"
    volumes:
      - ./config:/home/user/app/config
    environment:
      - CONFIG_FILE=./config/scanners.yml
      - APP_WORKERS=1

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