[SOLVED] Where to put boto3.Session creation in my FastAPI application?

Where to put boto3.Session creation in my FastAPI application?

I'm debating between either creating a global boto3.Session for my OpenSearch Python client or creating a new session at the beginning of every endpoint. I can't find documentation anywhere about when Sessions expire or if they expire. Every boto3.Session() call is costing me 50ms-100ms in latency, so it'd be great if I could just create a global one and have it never expire. Any guidance would be greatly appreciated.

Context: I've set up a Load Balanced Web Service on a public subnet to connect to my OpenSearch cluster in a private subnet, both in the same VPC. The Load Balanced Web Service is a FastAPI application.

Solution

The boto3.Sessions don't expire unless your credentials do. So, maintaining one global session make absolutely sense.

I'm not sure how you code is structured but you can find a basic example below:

from fastapi import FastAPI
import boto3

app = FastAPI()

session = boto3.Session() # ← global reusable boto3 session

@app.get("/some-endpoint")
def some_endpoint():
    client = session.client('opensearch')
    # ...
    return {"message": "Success"}