fastapi-agentrouter 0.4.0

AI Agent interface library for FastAPI with multi-platform support

FastAPI AgentRouter

Simplified AI Agent integration for FastAPI with Slack support.

Features

• 🚀 Simple Integration - Just 2 lines to add agent to your FastAPI app
• 🤖 Vertex AI ADK Support - Native support for Google's Agent Development Kit
• 💬 Slack Integration - Built-in Slack Bolt integration with lazy listeners
• 🎯 Protocol-Based - Works with any agent implementing stream_query method
• ⚡ Async & Streaming - Full async support with streaming responses
• 🧩 Dependency Injection - Leverage FastAPI's DI system
• 📁 Modular Architecture - Clean separation of concerns

Installation

# Basic installation
pip install fastapi-agentrouter

# With Slack support
pip install "fastapi-agentrouter[slack]"

# With Vertex AI ADK support
pip install "fastapi-agentrouter[vertexai]"

# All extras
pip install "fastapi-agentrouter[all]"

Quick Start

from fastapi import FastAPI
from fastapi_agentrouter import router, get_agent_placeholder

# Your agent implementation
class MyAgent:
    def stream_query(self, *, message: str, **kwargs):
        # Process the message and yield responses
        yield f"Response to: {message}"

app = FastAPI()

# Two-line integration!
app.dependency_overrides[get_agent_placeholder] = lambda: MyAgent()
app.include_router(router)

That's it! Your agent is now available at:

• /agent/slack/events - Handle all Slack events and interactions

Advanced Usage

With Vertex AI Agent Development Kit (ADK)

from fastapi import FastAPI
from fastapi_agentrouter import router, get_agent_placeholder
from vertexai.preview import reasoning_engines
from vertexai import Agent

# Define your agent with tools
def get_weather(city: str) -> dict:
    """Get weather for a city."""
    return {"city": city, "weather": "sunny", "temperature": 25}

agent = Agent(
    name="weather_agent",
    model="gemini-2.5-flash-lite",
    description="Weather information agent",
    tools=[get_weather],
)

def get_adk_app():
    return reasoning_engines.AdkApp(
        agent=agent,
        enable_tracing=True,
    )

app = FastAPI()
app.dependency_overrides[get_agent_placeholder] = get_adk_app
app.include_router(router)

Custom Agent Implementation

from fastapi import FastAPI
from fastapi_agentrouter import router, get_agent_placeholder

class CustomAgent:
    def stream_query(self, *, message: str, user_id=None, session_id=None, **kwargs):
        # Your custom logic here
        yield f"Response to: {message}"

def get_custom_agent():
    return CustomAgent()

app = FastAPI()
app.dependency_overrides[get_agent_placeholder] = get_custom_agent
app.include_router(router)

Disabling Slack Integration

import os
from fastapi import FastAPI
from fastapi_agentrouter import router, get_agent_placeholder

# Disable Slack integration via environment variable
os.environ["DISABLE_SLACK"] = "true"  # Slack endpoints will return 404

app = FastAPI()
app.dependency_overrides[get_agent_placeholder] = lambda: YourAgent()
app.include_router(router)

Configuration

Environment Variables

Configure Slack integration via environment variables using pydantic-settings:

# Required for Slack integration
export SLACK_BOT_TOKEN="xoxb-your-bot-token"
export SLACK_SIGNING_SECRET="your-signing-secret"

# Optional: Disable Slack integration
export DISABLE_SLACK="true"

Platform Setup

Slack Setup

1. Create a Slack App at https://api.slack.com/apps
2. Get your Bot Token and Signing Secret from Basic Information
3. Set environment variables:

   export SLACK_BOT_TOKEN="xoxb-your-bot-token"
   export SLACK_SIGNING_SECRET="your-signing-secret"
   

4. Configure Event Subscriptions URL: https://your-domain.com/agent/slack/events
5. Subscribe to bot events:
   • app_mention - When your bot is mentioned
   • message.im - Direct messages to your bot (optional)
6. For interactive components and slash commands, use the same URL: https://your-domain.com/agent/slack/events

Agent Protocol

Your agent must implement the stream_query method:

class AgentProtocol:
    def stream_query(
        self,
        *,
        message: str,
        user_id: Optional[str] = None,
        session_id: Optional[str] = None,
        **kwargs
    ) -> Iterator[Any]:
        """Stream responses for a message."""
        ...

The method should yield response events. For Vertex AI ADK, events have a content attribute.

API Reference

Core Components

fastapi_agentrouter.router

Pre-configured APIRouter with Slack integration:

• /agent/slack/events - Main Slack event handler

fastapi_agentrouter.get_agent_placeholder

Dependency placeholder that should be overridden with your agent:

app.dependency_overrides[fastapi_agentrouter.get_agent_placeholder] = your_get_agent_function

Environment Variables

The library uses pydantic-settings for configuration management:

• SLACK_BOT_TOKEN - Slack Bot User OAuth Token (required)
• SLACK_SIGNING_SECRET - Slack Signing Secret (required)
• DISABLE_SLACK=true - Disable Slack endpoints (return 404)

See the Configuration Guide for detailed documentation on all available settings.

Request body:

{
  "message": "Your message here",
  "user_id": "optional-user-id",
  "session_id": "optional-session-id"
}

Response:

{
  "response": "Agent response",
  "session_id": "session-id-if-provided"
}

Examples

See the examples directory for complete examples:

• basic_usage.py - Basic integration patterns
• More examples coming soon!

Development

Setup Development Environment

# Clone the repository
git clone https://github.com/chanyou0311/fastapi-agentrouter.git
cd fastapi-agentrouter

# Install with uv (recommended)
uv sync --all-extras --dev

# Or with pip
pip install -e ".[all,dev,docs]"

# Install pre-commit hooks
pre-commit install

Run Tests

# Run all tests
pytest

# Run with coverage
pytest --cov=src --cov-report=html

# Run specific tests
pytest tests/test_router.py

Build Documentation

# Serve docs locally
mkdocs serve

# Build docs
mkdocs build

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Links

• Documentation
• PyPI Package
• GitHub Repository
• Issue Tracker