Migration Guide: Simplified Rotating File Setup

This guide shows how to migrate from the verbose RotatingFileSinkConfig pattern to the new fapilog.sinks.rotating_file() convenience factory.

Before (Verbose Configuration)

from fapilog import get_logger
from fapilog.plugins.sinks.rotating_file import RotatingFileSink, RotatingFileSinkConfig
from pathlib import Path

config = RotatingFileSinkConfig(
    directory=Path("logs"),
    filename_prefix="app",
    max_bytes=10485760,
    max_files=7,
    compress_rotated=True,
)
sink = RotatingFileSink(config)
logger = get_logger(sinks=[sink])

After (Convenience Factory)

from fapilog import get_logger
from fapilog.sinks import rotating_file

logger = get_logger(
    sinks=[rotating_file("logs/app.log", rotation="10 MB", retention=7, compression=True)]
)

Notes

• The factory parses the path into directory + filename prefix automatically.

• Rotation values accept human-readable strings (e.g., "10 MB").

• Behavior is additive; the old configuration path still works.

Settings Alternative

from fapilog import Settings, get_logger
from fapilog.core.settings import RotatingFileSettings

settings = Settings(
    sink_config=Settings.SinkConfig(
        rotating_file=RotatingFileSettings(
            directory="logs",
            filename_prefix="app",
            max_bytes="10 MB",
            max_files=7,
            compress_rotated=True,
        )
    )
)
logger = get_logger(settings=settings)