Logging

People often do not use Python logging due to the setup cost. Hydra solves that by configuring the Python logging for you.

By default Hydra logs at the INFO level to both console and a file.

Example of logging with Hydra:

import logging

# A logger for this file
log = logging.getLogger(__name__)

@hydra.main()
def my_app(_cfg):
    log.info("Info level message")
    log.debug("Debug level message")

$ python my_app.py
[2019-06-27 00:52:46,653][__main__][INFO] - Info level message

You can enable DEBUG level logging from the command line by overriding hydra.verbose.

hydra.verbose can be a Boolean, a String or a List: Examples:

• hydra.verbose=true : Set all loggers log level to DEBUG
• hydra.verbose=__main__ : Set the __main__ logger log level to DEBUG
• hydra.verbose=[__main__,hydra]: Set the log levels of the loggers __main__ and hydra log to DEBUG

Example output:

$ python my_app.py hydra.verbose=[__main__,hydra]
[2019-09-29 13:06:00,880] - Installed Hydra Plugins
[2019-09-29 13:06:00,880] - ***********************
...
[2019-09-29 13:06:00,896][__main__][INFO] - Info level message
[2019-09-29 13:06:00,896][__main__][DEBUG] - Debug level message

Logging can be customized.