basicConfig

Learn configuration with logging.basicConfig.

basicConfig

logging.basicConfig configures the root logger in one line. With level you set the minimum level, with format the message format, with filename a file output.

import logging

logging.basicConfig(
    level=logging.DEBUG,
    format="%(levelname)s:%(message)s",
)
logger = logging.getLogger("myapp")
logger.info("merhaba")  # INFO:merhaba

basicConfig works only on the first call; later calls are ignored. So it is called once at program start.

Format placeholders

The format string shapes the message with placeholders. Common ones: %(asctime)s (time), %(levelname)s (level name), %(name)s (logger name), %(message)s (message).

format="%(asctime)s %(levelname)s %(message)s"
# 2025-01-01 12:00:00 INFO merhaba

A good format makes logs readable; time and level are usually important. Using a consistent format in long apps makes logs easier to scan.

Exercise Log with basicConfig

Start with import logging. Call logging.basicConfig(level=logging.DEBUG, format="%(levelname)s:%(message)s"). Get a logger with logger = logging.getLogger("myapp"). Write info with logger.info("merhaba").

Show example solution

import logging

logging.basicConfig(level=logging.DEBUG, format="%(levelname)s:%(message)s")
logger = logging.getLogger("myapp")
logger.info("merhaba")

Test yourself

Match the basicConfig concepts

level

Sets the minimum level
format

Sets the message format
filename

Writes to a file
%(levelname)s

Level name placeholder
What does the format parameter do in basicConfig?
- Sets the level
- Sets the message format
- Sets the logger name
- Sets the file name
Show answer

Sets the message format — The format parameter sets the message format with placeholders.

Complete the basicConfig call

import logging

logging.basicConfig(
    level=logging.____,
    format="%(levelname)s:%(message)s",
)

Show answer

import logging

logging.basicConfig(
    level=logging.DEBUG,
    format="%(levelname)s:%(message)s",
)

Next lesson: FileHandler

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