FastAPI + LangGraph Workflow Orchestration Template

A starter template for building AI-driven workflow orchestration systems using FastAPI and LangGraph. This project provides a modular foundation with state management, persistence, and REST APIs so you can quickly prototype and extend your own workflows.

Features

• FastAPI-based REST API endpoints for workflow management
• LangGraph integration for AI workflow orchestration
• Modular, extensible workflow architecture
• Built-in state management and checkpointing
• PostgreSQL-backed workflow persistence
• Support for workflow interrupts and continuations
• Non-blocking concurrent workflow execution using ThreadPoolExecutor
• LLM response validation and retry utilities with LiteLLM integration
• Added langfuse for observability and tracing

Prerequisites

• Python 3.11 or higher
• PostgreSQL database

Installation

1. Clone the repository:

git clone <repository-url>
cd agentic-template

2. Install dependencies:

pip install -r requirements.txt

3. Set up environment variables:

• Copy the example environment file:

cp .env.example .env

• Update values in .env to match your local setup (database URL, host, port, etc.).

Usage

1. Start the server:

• Default port (8000):

uvicorn app:app --reload

• Custom port:

uvicorn app:app --reload --port 8080

• Using environment variables (defined in .env):

uvicorn app:app --reload --port $PORT --host $HOST

🧩 API Endpoints

GET /

Description:
Retrieve API information and a list of available endpoints.

Response Example:

{
  "version": "1.0",
  "endpoints": [
    "/workflows/{workflow_name}",
    "/workflows/{workflow_name}/{thread_id}"
  ]
}

---

POST /workflows/{workflow_name}

Description:
Start a new workflow.

Request Body:

{
  "content": "{\"company_url\": \"https://www.github.com/\"}",
  "type": "text",
  "role": "user"
}

Response Example:

{
  "thread_id": "abc123",
  "status": "started",
  "workflow_name": "example_workflow"
}

---

POST /workflows/{workflow_name}/{thread_id}

Description:
Continue an existing workflow.

Request Body:

{
  "content": "{\"company_url\": \"https://www.github.com/\"}",
  "type": "text",
  "role": "user"
}

Response Example:

{
  "thread_id": "abc123",
  "status": "in_progress",
  "message": "Workflow updated successfully"
}

---

GET /workflows/{workflow_name}/{thread_id}

Description:
Retrieve the current state of a workflow thread.

Response Example:

{
  "thread_id": "abc123",
  "workflow_name": "example_workflow",
  "status": "completed",
  "result": {
    "summary": "Workflow execution finished successfully"
  }
}

Roadmap

Planned features and improvements:

• Add logging and log rotation in file
• Add authentication
• Add Prometheus metrics
• Add tool calling example
• Add rate limiting
• Replace sample agent with production-ready agent/chatbot (e.g., email agent)

Notes

• This repository is a template intended for customization. Replace example workflows, models, and configuration with your own domain logic.
• Consider adding authentication, rate limiting, and observability for production deployments.