klogr 0.2.0

Batteries-included structured logger for Python data/ML projects, built on Rich.

klogr

Batteries-included structured logger for Python data/ML projects — built on Rich.

  get_logger()
       |
       v
  +---------------------------+
  |        LoggingRich        |
  +---------------------------+
  | .info  .success  .warning |  -->  Rich-formatted console
  | .error .debug    .rule    |       with auto file:line prefix
  | .track .print    .info_json|
  +---------------------------+

  plus, from the same package:

    @lru_cache  +  DisableableLRUCache  -->  cached calls,
                                             with a disable hook for tests
    path_join / path_exists / path_open      -->  local + s3:// transparent
    get_elapsed_time(seconds)                -->  "01d : 01h : 12m : 03s"
    sha256sum(path) / get_cache_dir()        -->  stable on-disk caching

klogr is what you reach for when stdlib logging.basicConfig doesn't cut it and print() feels gross. It wraps Python's logging module with rich.logging.RichHandler pre-configured, adds stacklevel awareness so every line shows where it came from, and ships a handful of helpers (caching, paths, timing) that show up in every ML/data project.

Why use it

• Drop-in get_logger() — module-scoped, cached, zero setup. No logging.basicConfig, no handler wiring.
• Stacklevel-aware — every log line auto-prefixes with the caller's file:line. Stop hunting for which module shouted what.
• logger.track() — wraps rich.progress.track() and works inside ThreadPoolExecutor / ProcessPoolExecutor without going silent.
• logger.print() / logger.info_json() — pretty-print Pydantic models, dicts, JSON without piping through print(json.dumps(..., indent=2)).
• @lru_cache with a disable hook — flip an env var to bypass caching globally (handy for tests).
• Path helpers that handle S3 — path_join, path_exists, path_mkdir, etc. work whether you pass /tmp/foo or s3://bucket/foo.
• get_elapsed_time(seconds) — formats float seconds as 00d : 01h : 12m : 03s.
• One-liner dual output — with logger.to_file("run.log"): mirrors every log line to BOTH the Rich-formatted console AND the log file. Perfect for batch jobs.
• Timed blocks — with logger.timed("train epoch"): prints entry + exit + elapsed, no time.perf_counter() boilerplate.
• logger.exception("msg") — like stdlib logging.exception but the traceback is rendered by Rich.
• logger.kv(epoch=12, lr=3e-4) — one-line structured key=value logging for training loops.

Install

uv add klogr
# or
pip install klogr

Requires Python ≥ 3.10. Runtime deps: rich, pydantic, python-dotenv, beartype, jaxtyping, natsort, sha256sum.

Quickstart

from klogr import get_logger

logger = get_logger()

logger.info("loaded %d samples", 1024)         # auto file:line prefix
logger.success("training converged")            # green check
logger.warning("validation loss plateaued")
logger.error("OOM on batch 42")

# Pretty-print structured data
logger.print({"epoch": 12, "lr": 3e-4, "loss": 0.21})

# Progress bar that works in parallel
from concurrent.futures import ThreadPoolExecutor
with ThreadPoolExecutor(max_workers=8) as pool:
    for result in logger.track(pool.map(process, items), total=len(items), description="batch"):
        ...

What's in the box

Logger

from klogr import get_logger, LoggingRich, DEFAULT_VERBOSITY

logger = get_logger()                            # default verbosity
quiet  = get_logger({"info": False, "debug": False})  # custom

logger.info(msg)            # cyan
logger.success(msg)         # green check
logger.warning(msg)         # yellow
logger.error(msg)           # red
logger.rule(title)          # horizontal divider
logger.print(any_object)    # rich.print, soft-wrap aware
logger.info_json(json_str)  # syntax-colored JSON
logger.track(iter, total, description)  # progress bar

Log to console AND a file at the same time

from klogr import get_logger

logger = get_logger()

# Scoped to a block — auto-restores console-only on exit:
with logger.to_file("step.log"):
    logger.info("written to console AND step.log")
    logger.success("step done")
# back to console-only here

# Or set/unset manually if you need broader control:
logger.enable_dual_output("training.log")
logger.info("epoch=12")
logger.disable_dual_output()

The file gets the Rich-rendered output verbatim (colors stripped on the file side, preserved in the terminal). Check logger.is_file_enabled() to confirm dual output is on.

Time a block

with logger.timed("train epoch"):
    train_one_epoch()
# logs:  ▶ train epoch
#        ✓ train epoch — 00d : 00h : 12m : 03s

Structured key=value lines

logger.kv(epoch=12, lr=3e-4, loss=0.214)
# logs:  epoch=12 lr=0.0003 loss=0.214  (with rich coloring)

Log an exception with a Rich traceback

try:
    do_work()
except Exception:
    logger.exception("do_work failed")
# logs the message at ERROR, then a syntax-highlighted traceback

Caching

from klogr import lru_cache, DisableableLRUCache, get_cache_dir, sha256sum

@lru_cache(maxsize=128)
def expensive(key: str) -> bytes:
    ...

# Stable on-disk paths
cache_root = get_cache_dir()                          # XDG cache root
digest     = sha256sum("/path/to/file.bin")           # hex string

Path helpers (local + S3 transparent)

from klogr.path import (
    path_join, path_exists, path_mkdir, path_dirname,
    path_basename, path_glob, path_is_s3, path_open,
)

path_exists("/tmp/local.bin")       # True/False
path_exists("s3://bucket/key.bin")  # True/False (same call)
path_mkdir("/tmp/nested/dir", parents=True, exist_ok=True)
for p in path_glob("/data/*.jpg"):
    with path_open(p, "rb") as f:
        ...

Timing

from klogr import get_elapsed_time

print(get_elapsed_time(86400 + 3661))   # '01d : 01h : 01m : 01s'

Examples

Runnable scripts live in examples/:

• 01_basic_logger.py — log levels, formatting, file:line prefix
• 02_pretty_tables.py — LoggingTable for tabular console output
• 03_progress_tracking.py — logger.track() in parallel workers
• 04_caching.py — @lru_cache with disable-hook
• 05_path_helpers.py — local + S3 path ops

uv run examples/01_basic_logger.py

Layout

klogr/
├── __init__.py     # public re-exports
├── logger.py       # LoggingRich, LoggingTable, get_logger
├── cache.py        # lru_cache, DisableableLRUCache, sha256sum, get_cache_dir
├── path/           # local + S3 path helpers
│   ├── __init__.py
│   ├── ops.py      # pure ops (join, dirname, basename, suffix, …)
│   ├── env.py      # path_dotenv, path_home, path_expanduser
│   ├── io.py       # mkdir, remove, copy, move, read/write
│   └── query.py    # exists, is_dir, glob, listdir, stat
└── time.py         # get_elapsed_time

Build & test

uv sync
.venv/bin/pre-commit run --all-files
.venv/bin/pytest
.venv/bin/mypy klogr/

License

MIT — see LICENSE.md.