Could RAG pipelines realistically cause deployment timeouts, is Render suitable for first-time RAG deployments?

LangSmith Product Help Deployment
1

I built my first RAG-based AI education chatbot using Python + MongoDB vector storage, but deployment on Render fails with “No open ports detected.” I’m trying to figure out if this is caused by slow RAG startup, embedding initialization, or a configuration issue.

Github Repository: https://github.com/NjiruWinfred/RAG-Edulearn

Additional Technical Context

I’m still learning deployment and backend architecture, so some terminology may not be perfect yet.

Stack

  • Python backend

  • MongoDB for chat history and vector storage

  • RAG implementation for curriculum-aware responses

  • Hosted on Render

I’m not fully sure whether my structure is closer to Flask or FastAPI because I followed tutorials while learning, but the backend exposes API endpoints for the chatbot.

Startup Behavior

One thing I suspect is happening is that embeddings/vector retrieval initialization may be happening during startup before the server fully opens a port.

My theory is:

  • Render waits for the app to expose a port

  • The RAG initialization process takes too long

  • Render times out and throws:
    “No open ports detected”

Render Logs

The main error shown is:
“Error: No open ports detected”

I didn’t see a clear Python crash traceback, which is why I started suspecting startup timeout issues instead of syntax errors.

Startup Command

I used the standard Render startup command based on the tutorial/documentation I followed for running the Python app.

I’m still learning how production deployment differs from local development, so I may be missing best practices around:

  • lazy loading

  • async initialization

  • precomputed embeddings

  • separating vector indexing from app startup

Would appreciate any guidance or debugging ideas from more experienced developers :folded_hands:

Thank you so much in advance.

2

Hey @NjiruWinfred, took a quick peek. I see two issues:

  1. Last line references PORT, but PORT is never defined. NameError on execution.
  2. It seems that line is dedented, so it sits outside if __name__ == "__main__": and also fires on import (so uvicorn app:app crashes the same way).

should be something like:

PORT = int(os.getenv("PORT", 8000))

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=PORT)

The host needs to bind 0.0.0.0 on $PORT per Render’s port-binding docs, I believe this is handled, just needs PORT to actually exist.

Please let us know if this helps!

3

Thanks a lot!I’ve created a separate testing branch to implement your suggestion regarding the port binding. I’ll update this thread as soon as the build finishes to let you know if it resolved the timeout.

4

Hello @niilooy , I fixed the two issues and tried a few other things like lazy loading but I still got the same error. Here are the render logs: https://docs.google.com/document/d/1ftdFn8OyzOYmdJR4rqUFBE-yJf-j-FL0nbMFCAMeStM/edit?usp=sharing. Thankyou for your contribution.