Context Binding

Bind metadata to loggers so every record carries contextual information.

bind() - Persistent Context

from logly import logger

bound = logger.bind(user_id="12345", request_id="abc-789")
bound.info("User logged in")
# Output includes: user_id=12345 request_id=abc-789
logger.complete()

contextualize() - Scoped Context

from logly import logger

with logger.contextualize(session_id="xyz-000", env="prod"):
    logger.info("Inside session")
    logger.info("Still in session")
# Context restored after block
logger.complete()

patch() - Record Modification

from logly import logger

def add_version(record):
    record["extra"]["version"] = "2.1.0"
    record["extra"]["deploy"] = "eu-west-1"

logger.add("app.log", patch=add_version)
logger.info("Patched record")
logger.complete()

Scoped Child Logger

from logly import logger

child = logger.bind(component="auth")
child.info("Authentication started")

child2 = child.bind(action="login")
child2.info("Login attempt")
# Both component=auth and action=login appear
logger.complete()

Use context for tracing

Bind request_id or trace_id at the start of a request to correlate all logs within it.