GitHub App - Testing Locally

Introduction

Below is the complete working FastAPI example that:

• Listens on port 3000
• Handles:
  • POST /webhook — for GitHub webhooks
  • GET /callback — for GitHub OAuth callback

✅ FastAPI Server Creation Steps

• Create a main.py file for FastAPI Server

from fastapi import FastAPI, Request
from fastapi.responses import JSONResponse, PlainTextResponse
import uvicorn

app = FastAPI()

# POST /webhook endpoint
@app.post("/webhook")
async def webhook(request: Request):
    payload = await request.json()
    print(" Received webhook payload:", payload)
    return JSONResponse(content={"status": "received"}, status_code=200)

# GET /callback endpoint
@app.get("/callback")
async def callback(code: str = ""):
    print(f" OAuth callback code: {code}")
    return PlainTextResponse("OAuth callback received.", status_code=200)

if __name__ == "__main__":
    uvicorn.run("main:app", port=3000, reload=True)

• To Run

• Install FastAPI + Uvicorn:

pip install fastapi uvicorn

• Run the Server:

python main.py

• It will be available at http://localhost:3000

Sample URLs

• Webhook URL
  • http://localhost:3000/webhook
  • Use this in your GitHub App to receive event payloads like pushes, PRs, etc.
• Callback URL
  • http://localhost:3000/callback?code=…
  • GitHub will redirect to this URL after the user authorizes your app.
• Expose with Ngrok (Optional for GitHub to reach your local server)

ngrok http 3000

• Use the generated public URLs (like https://abc123.ngrok.io/webhook) in your GitHub App setup.