Rotate Log Files in Python by Size

import os
import glob
from pathlib import Path

def rotate_log(log_path, max_size_bytes=1024, max_backups=3):
    log_file = Path(log_path)
    if log_file.stat().st_size <= max_size_bytes:
        print(f"Log size {log_file.stat().st_size} bytes <= threshold, no rotation")
        return

    for i in range(max_backups, 0, -1):
        src = log_file.with_suffix(f".log.{i-1}" if i > 1 else ".log")
        dst = log_file.with_suffix(f".log.{i}")
        if src.exists():
            os.replace(src, dst)

    if log_file.exists():
        os.replace(log_file, log_file.with_suffix(".log.1"))

    log_file.touch()
    print(f"Rotated: created {log_file.name}, moved old to {log_file.name}.1")

if __name__ == "__main__":
    test_file = Path("test.log")
    test_file.write_text("x" * 100)  # 100 bytes, below threshold
    rotate_log(test_file, max_size_bytes=1024)

    test_file.write_text("y" * 2000)  # 2000 bytes, above threshold
    rotate_log(test_file, max_size_bytes=1024)

    # Cleanup
    for f in glob.glob("test.log*"):
        Path(f).unlink()