Sampling Debug Logs

Use filter-based sampling to trim DEBUG/INFO noise while keeping critical signals intact.

Probabilistic sampling (20%)

export FAPILOG_CORE__FILTERS='["sampling"]'
export FAPILOG_FILTER_CONFIG__SAMPLING__CONFIG__SAMPLE_RATE=0.2

from fapilog import get_async_logger

async def log_with_sampling():
    logger = await get_async_logger()
    await logger.debug("expensive debug payload", detail="...")
    await logger.info("high-volume event")
    # Sampling applies only to DEBUG/INFO; WARN/ERROR always pass.

Adaptive sampling (target EPS)

Keep a representative sample at high volume, ramp up sampling during quiet periods.

export FAPILOG_CORE__FILTERS='["adaptive_sampling"]'
export FAPILOG_FILTER_CONFIG__ADAPTIVE_SAMPLING__CONFIG__TARGET_EPS=150
export FAPILOG_FILTER_CONFIG__ADAPTIVE_SAMPLING__CONFIG__MIN_SAMPLE_RATE=0.01
export FAPILOG_FILTER_CONFIG__ADAPTIVE_SAMPLING__CONFIG__MAX_SAMPLE_RATE=1.0

Trace-aware sampling

Ensure whole traces stay together:

export FAPILOG_CORE__FILTERS='["trace_sampling"]'
export FAPILOG_FILTER_CONFIG__TRACE_SAMPLING__CONFIG__SAMPLE_RATE=0.15
export FAPILOG_FILTER_CONFIG__TRACE_SAMPLING__CONFIG__TRACE_ID_FIELD=trace_id

Migration note

The legacy observability.logging.sampling_rate setting now emits a DeprecationWarning. Switch to core.filters=["sampling"] (or adaptive_sampling / trace_sampling) with the corresponding filter_config.* block to avoid double-sampling and to expose sampling metrics.