vtt-info / urollingappenderlog

Simple micropython rolling appender logging

uRollingAppenderLog

Simple micropython rolling appender logging.

Send messages to the log file without fear of filling your storage space.

This class allows you to specify

• the name of the log file
• the maximum number of bytes you would like to log into a file
• how many backup versions of the log file you would like to maintain
• if you also want to print the messages to the console
• log_level

Backup files are given a suffix indicating how old they are. If max_backup is three then

• output.log (contains the newest log entries)
• output.log.1 (contains old log entries)
• output.log.2 (contains older log entries)
• output.log.3 (contains oldest log entries)

Files will be deleted when they surpass the max_backups value

Log level allows you to specify both the importance of the logged message and also control which messages are displayed by the logger

Log Level	Description
DEBUG	Detailed information, typically only of interest when diagnosing problems.
INFO	Confirmation that things are working as expected.
ERROR	Due to a more serious problem, the software has not been able to perform some function.

The level assigned to the logger shows output

Logger Level	DEBUG	INFO	ERROR
DEBUG	✓	✓	✓
INFO		✓	✓
ERROR			✓

✓ indicates that the corresponding log level will be output.
Blank cells indicate that the corresponding log level will not be output.
The rows represent the log level set for the logger instance.
The columns represent the log levels of the messages.

Messages are logged with the following pattern

  TID:{TID}-{prefix}-{message}

  where
    TID: is a literal string denoting the start of a message.
    {TID} is the UTC timestamp supplied to the log_message function, defaulting to 0000-00-00T00:00:00Z NOTE: the supplied TID is not validated
    {prefix} is a literal string representation of the log_level supplied to the log_message function.
    {message} is the message supplied to the log_message function.

NOTE: Exceptions are not handled within the class and will propogate up the call stack.

# test_logging_app.py

from rolling_appender_log import uRollingAppenderLog, LogLevel

# Instantiate the URollingAppenderLog class with default values
logger = URollingAppenderLog("logger.log")

# Instantiate the URollingAppenderLog class for debugging
logger2 = URollingAppenderLog("logger2.log", LogLevel.DEBUG)

# Instantiate the URollingAppenderLog class for recording only ERROR messages
logger2 = URollingAppenderLog("logger2.log", LogLevel.DEBUG)

# Log messages
logger.log_message("This is an info message.")
logger.log_message("This is another info message.", LogLevel.INFO)
logger.log_message("This is a debug message.", LogLevel.DEBUG)
logger.log_message("This is an error message.", LogLevel.ERROR)
logger.log_message("This is an error message with a specified TID.", LogLevel.ERROR, "2024-01-01T23:59:59Z")

# Log messages
logger2.log_message("This is an info message.")
logger2.log_message("This is another info message.", LogLevel.INFO)
logger2.log_message("This is a debug message.", LogLevel.DEBUG)
logger2.log_message("This is an error message.", LogLevel.ERROR)
logger2.log_message("This is an error message with a specified TID.", LogLevel.ERROR, "2024-01-01T23:59:59Z")

If you want to specify the maximum size of a log file in bytes along with the number of backup files or print messages you can adjust the instantiation

# test_logging_app.py

from rolling_appender_log import uRollingAppenderLog, LogLevel

# Instantiate the URollingAppenderLog class with custom values
logger = URollingAppenderLog("test_log.log", max_file_size_bytes=1024, max_backups=3, print_messages=True, LogLevel.DEBUG)

# Log a message
logger.log_message("This is a test message.")