Logging¶

ondio writes short log lines about what it is doing, such as which backend a URI uses and whether a FLAC window is fetched with a byte range. The lines only describe progress: every failure raises an exception, so nothing is lost if you never see them.

Where the lines go¶

ondio uses the Printer from cocina when cocina is installed. cocina is not a dependency of ondio; without it, ondio logs nothing.

cocina's Printer is one object for the whole process, and the first code to construct it sets its configuration. ondio never constructs it at import, so if your application constructs Printer(...) before ondio's first log line, your configuration is used.

Your own logger¶

ondio.set_printer sends the lines to any object with a message method instead. This example passes them to Python's logging:

import logging

import ondio

log = logging.getLogger("ondio")


class ToLogging:
    def message(self, text, *args, **kwargs):
        log.info(text)


ondio.set_printer(ToLogging())

The setting applies to the whole process. ondio.set_printer(None) goes back to the default.

Turning it off¶

An object without a message method receives nothing, so this silences ondio even when cocina is installed:

ondio.set_printer(object())