Adding python logging to FastApi endpoints, hosted on docker doesn't display API Endpoints logs

Question

I have a fastapi app on which I want to add python logging. I followed the basic tutorial and added this, however this doesn't add API but just gunicorn logging.

So I have a local server hosted using docker build so running server using docker-compose up and testing my endpoints using api client (Insomnia, similar to postman). Below is the code where no log file is created and hence no log statements added.

My project str is as follows:

project/
  src/ 
    api/
      models/ 
        users.py
      routers/
        users.py
      main.py
      logging.conf

"""
main.py Main is the starting point for the app.
"""
import logging
import logging.config
from fastapi import FastAPI
from msgpack_asgi import MessagePackMiddleware
import uvicorn

from api.routers import users


logger = logging.getLogger(__name__)


app = FastAPI(debug=True)
app.include_router(users.router)


@app.get("/check")
async def check():
    """Simple health check endpoint."""
    logger.info("logging from the root logger")
    return {"success": True}

Also, I am using gunicorn.conf that looks like this:

[program:gunicorn]
command=poetry run gunicorn -c /etc/gunicorn/gunicorn.conf.py foodgame_api.main:app
directory=/var/www/
autostart=true
autorestart=true
redirect_stderr=true

And gunicorn.conf.py as

import multiprocessing
bind = "unix:/tmp/gunicorn.sock"
workers = multiprocessing.cpu_count() * 2 + 1
worker_class = "uvicorn.workers.UvicornWorker"
loglevel = "debug"
errorlog = "-"
capture_output = True
chdir = "/var/www"
reload = True
reload_engine = "auto"
accesslog = "-"
access_log_format = '%(h)s %(l)s %(u)s %(t)s "%(r)s" %(s)s %(b)s "%(f)s" "%(a)s"'

This is my output terminal for the above API endpoint on docker:

Could anyone please guide me here? I am new to FastApi so some help will be appreciated.

seems like the logger isn't enabled. – JPG Aug 20 '20 at 19:22 — JPG, Aug 20 '20 at 19:22
@ArakkalAbu How do you enable logger? – Atihska Aug 21 '20 at 00:36 — Atihska, Aug 21 '20 at 00:36
Also look at [loguru](https://github.com/Delgan/loguru). – Yash Nag Sep 15 '21 at 17:47 — Yash Nag, Sep 15 '21 at 17:47

score 58 · Answer 1 · edited Dec 16 '22 at 12:59

Inspired by @JPG's answer, but using a pydantic model looked cleaner.

You might want to expose more variables. This config worked good for me.


from pydantic import BaseModel

class LogConfig(BaseModel):
    """Logging configuration to be set for the server"""

    LOGGER_NAME: str = "mycoolapp"
    LOG_FORMAT: str = "%(levelprefix)s | %(asctime)s | %(message)s"
    LOG_LEVEL: str = "DEBUG"

    # Logging config
    version = 1
    disable_existing_loggers = False
    formatters = {
        "default": {
            "()": "uvicorn.logging.DefaultFormatter",
            "fmt": LOG_FORMAT,
            "datefmt": "%Y-%m-%d %H:%M:%S",
        },
    }
    handlers = {
        "default": {
            "formatter": "default",
            "class": "logging.StreamHandler",
            "stream": "ext://sys.stderr",
        },
    }
    loggers = {
        LOGGER_NAME: {"handlers": ["default"], "level": LOG_LEVEL},
    }

Then import it into your main.py file as:

from logging.config import dictConfig
import logging
from .config import LogConfig

dictConfig(LogConfig().dict())
logger = logging.getLogger("mycoolapp")

logger.info("Dummy Info")
logger.error("Dummy Error")
logger.debug("Dummy Debug")
logger.warning("Dummy Warning")

Which gives:

how do you then log to a particular file or directory? Any Documentation? — Young Emil, Sep 23 '21 at 16:46
@YoungEmil See [this answer](https://stackoverflow.com/a/66728490/9549847). Just add the file handler and assign it to your logger. — Yash Nag, Sep 24 '21 at 07:49
Why would you use a pydantic model for something that's essentially a static dict? — previous_developer, Nov 03 '22 at 11:44
@previous_developer Used it with `BaseSettings` rather than `BaseModel` later. Picks up env vars, easy to write custom ops, it's great. — Yash Nag, Dec 13 '22 at 19:08

score 19 · Answer 2 · answered Aug 21 '20 at 03:09

I would use dict log config

create a logger config as below,

# my_log_conf.py

log_config = {
    "version": 1,
    "disable_existing_loggers": False,
    "formatters": {
        "default": {
            "()": "uvicorn.logging.DefaultFormatter",
            "fmt": "%(levelprefix)s %(asctime)s %(message)s",
            "datefmt": "%Y-%m-%d %H:%M:%S",

        },
    },
    "handlers": {
        "default": {
            "formatter": "default",
            "class": "logging.StreamHandler",
            "stream": "ext://sys.stderr",
        },
    },
    "loggers": {
        "foo-logger": {"handlers": ["default"], "level": "DEBUG"},
    },
}

Then, load the config using dictConfig function as,

from logging.config import dictConfig
from fastapi import FastAPI

from some.where.my_log_conf import log_config

dictConfig(log_config)

app = FastAPI(debug=True)

Note: It is recommended to call the dictConfig(...) function before the FastAPI initialization.

After the initialization, you can use logger named foo-logger anywhere in your code as,

import logging

logger = logging.getLogger('foo-logger')

logger.debug('This is test')

It doesn't work for me. I only see gunicorn request based HTTP logs and not the ones I print using logging module on path functions. — Atihska, Aug 25 '20 at 00:28
Do you see any logs if you are running without docker? btw, this example should work as-is with both gunicorn as well as with uvicorn — JPG, Aug 25 '20 at 02:09
BTW, I did test this solution in the Docker environment too, and it seems fine. You can test the same with this demo project of [mine, with branch **`so-63510041`**](https://github.com/jerinpetergeorge/fast-api-example/tree/so-63510041). You will find the commands in the `README.md` — JPG, Aug 25 '20 at 03:00

Adding python logging to FastApi endpoints, hosted on docker doesn't display API Endpoints logs

2 Answers2