starlette context

Middleware for Starlette that allows you to store and access the context data of a request. Can be used with logging so logs automatically use request headers such as x-request-id or x-correlation-id.

Motivation

I use FastAPI. I needed something that will allow me to log with context data. Right now I can just log.info('Message') and I have log (in ELK) with request id and correlation id. I don't even think about passing this data to logger. It's there automatically.

Installation

$ pip install starlette-context

Requirements

Python 3.7+

For Python 3.6 only:
contextvar came out with python3.7 and is required for this to run. If you need to use Starlette with python3.6, there is a backport of contextvar for py36. https://github.com/MagicStack/contextvars

Dependencies

• starlette

All other dependencies from requirements-dev.txt are only needed to run tests or examples. Test/dev env is dockerized if you want to try them yourself.

Example

examples/simple_examples/set_context_in_middleware.py

from starlette.applications import Starlette
from starlette.requests import Request
from starlette.responses import JSONResponse

import uvicorn
from starlette_context import context, plugins
from starlette_context.middleware import ContextMiddleware


app = Starlette(debug=True)
app.add_middleware(ContextMiddleware.with_plugins(  # easily extensible
    plugins.RequestIdPlugin,  # request id
    plugins.CorrelationIdPlugin  # correlation id
))


@app.route('/')
async def index(request: Request):
    return JSONResponse(context.data)


uvicorn.run(app, host="0.0.0.0")

In this example the response containes a json with

{
  "X-Correlation-ID":"5ca2f0b43115461bad07ccae5976a990",
  "X-Request-ID":"21f8d52208ec44948d152dc49a713fdd"
}

Context can be updated and accessed at anytime if it's created in the middleware.

Contribution

All tickets or PRs are more than welcome.