Flask Logging Logger Configuration

app.py

import sys
import logging
import logging.config

from flask import Flask
class LoggerConfig:
    dictConfig = {
        'version': 1,
        'disable_existing_loggers': False,
        'formatters': {
            'standard': { 'format': '%(asctime)s - %(name)s - %(levelname)s - '
                          '%(message)s - [in %(pathname)s:%(lineno)d]'},
            'short': { 'format': '%(message)s' } 
        },
        'handlers': {
            'default': {
                'level': 'DEBUG',
                'formatter': 'standard',
                'class': 'logging.handlers.RotatingFileHandler',
                'filename': 'femm-api.log',
                'maxBytes': 5000000,
                'backupCount': 10
            },
            'debug': {
                'level': 'DEBUG',
                'formatter': 'standard',
                'class': 'logging.StreamHandler'
            },
           'console': {
            'class': 'logging.StreamHandler',
            'level': 'DEBUG'
           },
        },
        'loggers': {
            'femmapi': {
                'handlers': ['default'],
                'level': 'DEBUG',
                'propagate': True},
            'werkzeug': { 'propagate': True },
        },
        # 'root': { 'level': 'DEBUG', 'handlers': ['console'] }
    }


app = Flask(__name__)
app.config['LOGGER_HANDLER_POLICY'] = 'always'  # 'always' (default), 'never',  'production', 'debug'
app.config['LOGGER_NAME'] = 'femmapi' # define which logger to use for Flask
app.logger #  initialise logger

if len(sys.argv) > 1 and sys.argv[1] == 'debug':
    app.debug = True

logging.config.dictConfig(LoggerConfig.dictConfig)

print(app.logger.name)

app.logger.debug('debug message')
app.logger.info('info message')
app.logger.warn('warn message')
app.logger.error('error message')
app.logger.critical('critical message')

This is no longer valid for Flask 1.0. see docs: http://flask.pocoo.org/docs/1.0/api/#flask.Flask.logger

the Logger for Flask should be named flask.app

no need for

app.config['LOGGER_HANDLER_POLICY'] = 'always'  # 'always' (default), 'never',  'production', 'debug'
app.config['LOGGER_NAME'] = 'femmapi' # define which logger to use for Flask
app.logger #  initialise logger