opentelemetry-instrumentation-logging JSON Formatter compatibility with spec

[tailg8nj]

The spec for log formatting, specifically JSON has an example:

https://opentelemetry.io/docs/specs/otel/compatibility/logging_trace_context/#json-formats

Which seems to reinforce the overview of logging Trace ID and Span ID in legacy log formats:

To summarize, the following field names should be used in legacy formats:

“trace_id” for TraceId, lowercase and hex-encoded.
“span_id” for SpanId, lowercase and hex-encoded.
“trace_flags” for trace flags, formatted according to W3C traceflags format.

However, the log record that is created with the opentelemetry-instrumentation-logging has fields named otelTraceID and otelSpanID, etc.:

opentelemetry-python-contrib/instrumentation/opentelemetry-instrumentation-logging/src/opentelemetry/instrumentation/logging/__init__.py

Lines 203 to 205 in 26c975f

	record.otelSpanID = format(ctx.span_id, "016x")
	record.otelTraceID = format(ctx.trace_id, "032x")
	record.otelTraceSampled = ctx.trace_flags.sampled

This doesn't rear it's head with standard text formatters as the default logging format pulls the appropriate log record attributes out explicitly:

opentelemetry-python-contrib/instrumentation/opentelemetry-instrumentation-logging/src/opentelemetry/instrumentation/logging/constants.py

Line 4 in 26c975f

DEFAULT_LOGGING_FORMAT = "%(asctime)s %(levelname)s [%(name)s] [%(filename)s:%(lineno)d] [trace_id=%(otelTraceID)s span_id=%(otelSpanID)s resource.service.name=%(otelServiceName)s trace_sampled=%(otelTraceSampled)s] - %(message)s"

JSON formatters traditionally just take what they are given and spit them out, see reference implementation: python-json-logger.

I believe the attributes placed onto the log record should change to snake case, and the default text format changed to leverage them appropriately.

[rajdhruvsingh]

Hi, I'm interested in working on this. Before implementing,
I wanted to clarify the migration strategy:

1. The current attribute names (otelSpanID, otelTraceID,
   otelTraceSampled, otelServiceName) are documented and
   widely used in log format strings. Renaming them is a
   breaking change.

2. Would the preferred approach be:
   a) Add new spec-compliant names alongside existing ones
   (both work, old ones deprecated with warning)?
   b) Use OTEL_SEMCONV_STABILITY_OPT_IN style opt-in?
   c) Only change in next major version?

3. Should DEFAULT_LOGGING_FORMAT be updated to use new names?

Would appreciate guidance before implementing.