[Logging tip] #fastapi #python

logging.yml

version: 1
disable_existing_loggers: False
formatters:
    simple:
        format: "%(asctime)s - %(name)s - %(lineno)d - %(levelname)s - %(message)s"
handlers:
    console:
        class: logging.StreamHandler
        level: DEBUG
        formatter: simple
        filters:
            - healthcheck_filter
        stream: ext://sys.stdout
    info_file_handler:
        class: logging.handlers.RotatingFileHandler
        level: INFO
        formatter: simple
        filename: applog/info.log
        maxBytes: 10485760 # 10MB
        backupCount: 20
        encoding: utf8
    error_file_handler:
        class: logging.handlers.RotatingFileHandler
        level: ERROR
        formatter: simple
        filename: applog/errors.log
        maxBytes: 10485760 # 10MB
        backupCount: 20
        encoding: utf8
loggers:
    uvicorn:
        level: INFO
        handlers: [console]
        propagate: no
    gunicorn:
        level: INFO
        handlers: [console]
        propagate: no
filters:
  healthcheck_filter:
    "()": applog.utils.NoHealthCheckFilter
root:
    level: INFO
    handlers: [console]

notes.md

From: https://gitlab.com/euri10/euri10_fastapi_base

euri10 @euri10 Jun 27 09:31 well I just did it, quite simple in fact L) will add it to my logging facility you can see it here : euri10/euri10_fastapi_base@814404f in summary I added this to my docker-compose

healthcheck:
  	test: ["CMD", "wget", "http://localhost:8000/healthcheck"]
  	interval: 1s

which effectively spams the logger every second

@app.get("/healthcheck")
async def healthcheck():
	return {"status": "alive"}

now it depends how logging is performed on your app in my case everything is configured through a logging.yaml that is read at app initialization and then setup with

logging.config.dictConfig(logging_config)

euri10 @euri10 Jun 27 09:38 so depending on how you configuire it, the only thing to know is you add a filter to the handler that spits the log you want to avoid,

it's here : https://gitlab.com/euri10/euri10_fastapi_base/blob/814404fc44636c8ebd04af91e33cb325f72db294/python3.7-alpine3.8/app/applog/logging.yml#L12

then you declare a custom filter , it's here : https://gitlab.com/euri10/euri10_fastapi_base/blob/814404fc44636c8ebd04af91e33cb325f72db294/python3.7-alpine3.8/app/applog/logging.yml#L41

then you write that custom filter class subclassing logging.Filter, its here https://gitlab.com/euri10/euri10_fastapi_base/blob/814404fc44636c8ebd04af91e33cb325f72db294/python3.7-alpine3.8/app/applog/utils.py#L32 pretty simple in fact

utils.py

import logging.config
import os

import yaml


def read_logging_config(default_path="logging.yml", env_key="LOG_CFG"):
    path = default_path
    value = os.getenv(env_key, None)
    if value:
        path = value
    if os.path.exists(path):
        with open(path, "rt") as f:
            logging_config = yaml.safe_load(f.read())
        return logging_config
    else:
        return None


def setup_logging(logging_config, default_level=logging.INFO):
    if logging_config:
        logging.config.dictConfig(logging_config)
    else:
        logging.basicConfig(level=default_level)


class NoHealthCheckFilter(logging.Filter):
    def __init__(self, param=None):
        self.param = param

    def filter(self, record):
        return record.getMessage().find('/healthcheck') == -1