clp-logging 0.0.1

Logging/encoding/decoding using CLP's IR stream format

CLP Logging

This is a Python logging library meant to supplement CLP. To learn more about CLP check out the repository and Uber's blog.

To achieve the best compression ratio, CLP should be used to compress large batches of related log events, one batch at a time. However, individual log files are generally small and are generated across a long period of time.

This logging library helps solve this problem by logging directly in CLP's internal representation (IR). A log created with a CLP logging handler is first parsed and then appended to a compressed output stream in IR form. See README-protocol.md for more details on the format of CLP IR.

These log files containing the compressed CLP IR streams can then all be ingested into CLP together at a later time.

Logger handlers

CLPStreamHandler

• Writes encoded logs directly to a stream

CLPFileHandler

• Simple wrapper around CLPStreamHandler that calls open

Example: CLPFileHandler

import logging
from pathlib import Path
from clp_logging.handlers import CLPFileHandler

clp_handler = CLPFileHandler(Path("example.clp.zst"))
logger = logging.getLogger(__name__)
logger.addHandler(clp_handler)
logger.info("hello")

CLPSockHandler + CLPSockListener

• A Unix domain socket logging handler and listener server to enable multiple concurrent handlers across multiple processes to log to the same log file.
• The handler writes encoded logs and sends them over the socket to the separate listener process
  • Socket name is the log file path passed to CLPSockHandler with a ".sock" suffix
• On creation a CLPSockHandler will try to connect to the listener associated with its socket name
• CLPSockListener is essentially a namespace as it is a class, but only contains static methods and data
• A CLPSockListener can be explicitly created (and will run as a daemon) by calling:
  • CLPSockListener.fork(log_path, sock_path, timezone, timestamp_format)
• Alternatively CLPSockHandlers can transparently start an associated CLPSockListener
  • Call CLPSockHandler with create_listener=True
• Multiple CLPSockHandlers logging to the same file will use the same socket and therefore the same listener
  • It is safe for these handlers to all use create_listener=True
    • They will race to create a listener with only one successfully binding the socket and living on
    • All the handlers will then connect to the one successful listener
• CLPSockListener must be explicitly stopped once logging is completed
  • Send CLPSockListener process SIGTERM
  • Use an existing handler or create a new handler with the same log path and call stop_listener
    • clp_sock_handler.stop_listener() or CLPSockHandler(Path("example.clp.zst")).stop_listener()

Example: CLPSockHandler + CLPSockListener

In the handler processes or threads:

import logging
from pathlib import Path
from clp_logging.handlers import CLPSockHandler

clp_handler = CLPSockHandler(Path("example.clp.zst"), create_listener=True)
logger = logging.getLogger(__name__)
logger.addHandler(clp_handler)
logger.info("hello")

In a single process or thread once logging is completed:

from pathlib import Path
from clp_logging.handlers import CLPSockHandler

CLPSockHandler(Path("example.clp.zst")).stop_listener()

CLP readers (decoders)

CLPStreamReader

• Read/decode any arbitrary stream
• Can be used as an iterator that returns each log message as an object
• Can skip n logs: clp_reader.skip_nlogs(N)
• Can skip to first log after given time (since unix epoch):
  • clp_reader.skip_to_time(TIME)

CLPFileReader

• Simple wrapper around CLPStreamHandler that calls open

Example code: CLPFileReader

import logging
from pathlib import Path
from clp_logging.readers import CLPFileReader, Log

# create a list of all Log objects
log_objects: List[Log] = []
with CLPFileReader(Path("example.clp.zst") as clp_reader:
    for log in clp_reader:
        log_objects.append(log)

Compatibility

Tested on Python 3.6 and 3.8 and should work on any newer version. Built/packaged on Python 3.8 for convenience regarding type annotation.

Building/Packaging

1. Create and enter a virtual environment: python3.8 -m venv venv; . ./venv/bin/activate
2. Install development dependencies: pip install -r requirements-dev.txt
3. Build: python -m build

Testing

Note the baseline comparison logging handler and the CLP handler both get unique timestamps. It is possible for these timestamps to differ, which will result in a test reporting a false positive error.

1. Create and enter a virtual environment: python -m venv venv; . ./venv/bin/activate
2. Install: pip install dist/clp_logging-0.0.1-py3-none-any.whl or pip install -e .
3. Run unittest: python -m unittest -bv

Contributing

Ensure to run mypy and black (found in requirements-dev.txt) during development to ensure smooth pull requests.