Deploying a FastAPI App

FastAPI is a modern, high-performance web framework for building APIs with Python 3.7+ based on standard Python type hints. It is known for its speed, automatic documentation, and ease of use, making it a top choice for building robust RESTful APIs and microservices.

This guide explains how to deploy a FastAPI application to Klutch.sh, both with and without a Dockerfile. It also covers installation and provides sample code to get started.

Prerequisites

• Python 3.8+
• pip installed
• Git and GitHub account
• Klutch.sh account

---

Getting Started: Install FastAPI

1. Create a new directory for your app and set up a virtual environment:

   mkdir my-fastapi-app
   cd my-fastapi-app
   python3 -m venv venv
   source venv/bin/activate

2. Install FastAPI and Uvicorn:

   pip install fastapi uvicorn

3. Create a basic FastAPI app (main.py):

   from fastapi import FastAPI
   import os
   
   app = FastAPI()
   
   @app.get("/")
   def read_root():
       return {"message": "Hello from FastAPI on Klutch.sh!"}
   
   if __name__ == "__main__":
       port = int(os.environ.get("PORT", 8000))
       import uvicorn
       uvicorn.run(app, host="0.0.0.0", port=port)

4. Add a requirements.txt file:

   pip freeze > requirements.txt

5. Test locally:

   python main.py

   Visit http://localhost:8000 to see your app running.

---

Deploying Without a Dockerfile

1. Push your FastAPI app to a GitHub repository.
2. Log in to Klutch.sh.
3. Create a new project and give it a name.
4. Create a new app:
   • Select your FastAPI GitHub repository and branch
   • Set the port to route traffic (usually 8000 for FastAPI)
   • Choose region, compute, number of instances, and add any environment variables
5. Add a start command in your app settings:

   python main.py

6. Click “Create” to deploy. Klutch.sh will build and deploy your app automatically.

---

Deploying With a Dockerfile

1. Add a Dockerfile to your project root. Example:

   # Use official Python image
   FROM python:3.11-slim
   
   # Set working directory
   WORKDIR /app
   
   # Copy requirements and install dependencies
   COPY requirements.txt ./
   RUN pip install --no-cache-dir -r requirements.txt
   
   # Copy app source
   COPY . .
   
   # Expose port (match your FastAPI app)
   EXPOSE 8000
   
   # Start the app
   CMD ["python", "main.py"]

2. Push your code (with Dockerfile) to GitHub.
3. In Klutch.sh, follow the same steps to create a project and app, but select the Dockerfile option when prompted.
4. Set the service details and environment variables as needed.
5. Click “Create” to deploy. Klutch.sh will build your Docker image and deploy your app.

Note: Your FastAPI app should always listen on the PORT environment variable as shown above.

---

Resources

• Klutch.sh Documentation
• FastAPI Documentation

---

Deploying to Klutch.sh is simple and flexible. Choose the method that best fits your workflow and project requirements.