Trace-based Log Sampler

This processor is used to sample logs based on the sampling decision of the trace they correlate to.

How It Works

When a trace is sampled, the processor caches its traceId. Logs are then filtered:

• If a log references a known sampled traceId, it is beimg forwarded.
• If a log references an unknown or unsampled traceId, it is buffered for a certain amount of time. After the buffer time expires, the traceId is checked again. If it exists, the log is forwarded. If not, it is discarded.

Configuration

Field	Type	Default	Description
buffer_duration_traces	duration	180s	The duration for which traceIds are being remembered. The timer starts when the first trace or span of one traceId is received.
buffer_duration_logs	duration	90s	The duration for which logs are being buffered for, before being re-evaluated. If your pipeline includes e.g. a tailbasedsampler processor, set this to above it's collection time. This ensures that logs "wait" until the traces have been processed

Example Configuration

The followinh config is an example configuration for the processor. It is configured to buffer traceIds for 180 seconds and logs for 90 seconds.

Note that both a traces and logs pipeline is required and both have to use the same instance of the processor.

receivers:
  otlp:
    protocols:
      grpc:
        endpoint: 0.0.0.0:4317

exporters:
  otlp:
    endpoint: 0.0.0.0:4317

processors:
  logtracesampler:
    buffer_duration_traces: 180s
    buffer_duration_logs: 90s

service:
  pipelines:
    traces:
      receivers: [otlp]
      processors: [logtracesampler]
      exporters: [otlp]

    logs:
      receivers: [otlp]
      processors: [logtracesampler]
      exporters: [otlp]

Building

When building a custom collector you can add this processor to the mainfest like the following (refer to Building a custom collector for more information):

processors:
  - gomod: gitea.t000-n.de/t.behrendt/tracebasedlogsampler v0.0.0