Middleware in FastAPI for generating UUID for every request and send to logs

user_13115238 0
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I'm looking for a middleware in Fast API for generating UUID for every request and send it to logs.

# To see the logs, run this in python interpreter
# import with_logger
# with_logger.main()

import uuid
from logging import getLogger
import logging.config
from yaml import load, FullLoader
from fastapi import FastAPI
import uvicorn

app = FastAPI()


# @app.middleware("http")
@app.get("/")
def gen_uuid():
    # For every get request generate uuid
    global uuid_var
    uuid_var = uuid.uuid4()
    return uuid_var


log_dict = {
    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'standard': {
            'format': '%(uuid_var)s %(asctime)s %(levelname)-8s %(name)-15s %(message)s -Thread id: %(thread)d  Thread name: %(threadName)s'
        },
    },
    'handlers': {
        'default': {
            'level': 'INFO',
            'formatter': 'standard',
            'class': 'logging.StreamHandler',
        },
        'file_handler': {
            'level': 'INFO',
            'filename': 'mylogfile.log',
            'class': 'logging.FileHandler',
            'formatter': 'standard'
        }
    },
    'loggers': {
        '': {
            'handlers': ['file_handler'],
            'level': 'INFO',
            'propagate': True
        },
    }
}


class ContextFilter(logging.Filter):
    def filter(self, record):
        record.uuid_var = gen_uuid()
        return True


def main():
    logging.config.dictConfig(log_dict)

    handler = logging.StreamHandler()
    handler.formatter = logging.Formatter(
        "%(uuid_var)s %(asctime)s %(levelname)-8s %(name)-15s %(message)s -Thread id: %(thread)d  Thread name: %(threadName)s")
    handler.addFilter(ContextFilter())
    logger = getLogger(__name__)
    logger.addHandler(handler)

    logger.warning(" This is a warning message")

    uvicorn.run(app, host="127.0.0.1", port=8080)

I need the uuid to be sent to the X-Request-ID header and I'll use python logging library to fetch it from there like,

@app.middleware("http")
async def get_x_request_id_header(*, x_request_id: str = Header(None)):
    # return x-request-id header
    return {"X-Request-ID": x_request_id}

I need all this in a middleware. Is there a middleware which already exists something like this in Fast API?

I need to generate the uuid inside the middleware like,

@app.middleware("http")
def gen_uuid():
    # For every get request generate uuid
    global uuid_var
    uuid_var = uuid.uuid4()
    return uuid_var

But not able to do this. I get error like gen_uuid accepts 2 parameters but passing 0 parameters

fastapi request python-3.x logging python
2 Answers
user_80834590

Middleware needs two parameters: request: Request, call_next request is the api request and call_next is the actual call to process the request Something like this:

    @app.middleware("http")
async def init_requestvars(request: fastapi.Request, call_next):
    # Customize that SimpleNamespace with hatever you need
    initial_g = types.SimpleNamespace()
    requestvars.request_global.set(initial_g)
    response = await call_next(request)
    return response
user_58276620
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