ashb commented on code in PR #68591:
URL: https://github.com/apache/airflow/pull/68591#discussion_r3419095658
##########
shared/observability/src/airflow_shared/observability/traces/__init__.py:
##########
@@ -61,15 +62,51 @@ def generate_trace_id(self):
def new_dagrun_trace_carrier(task_span_detail_level=None) -> dict[str, str]:
- """Generate a fresh W3C traceparent carrier without creating a recordable
span."""
+ """
+ Generate a fresh W3C traceparent carrier without creating a recordable
span.
+
+ The SAMPLED flag is set from an honest *root* sampling decision made by the
+ configured tracer provider's sampler (driven by ``OTEL_TRACES_SAMPLER`` /
+ ``OTEL_TRACES_SAMPLER_ARG``), rather than being hardcoded. This makes the
+ carrier the single head-sampling decision point for a DAG run: every
+ downstream span (dag_run, task_run, worker) rides on this flag.
+
+ Backcompat: when ``OTEL_TRACES_SAMPLER`` is unset the SDK defaults to
+ ``parentbased_always_on`` whose root decision is ALWAYS_ON, so the flag is
+ SAMPLED and behavior is identical to the previous hardcoded value.
+ """
gen = RandomIdGenerator()
- trace_state_entries = build_trace_state_entries(task_span_detail_level)
+ trace_id = gen.generate_trace_id()
+
+ provider = trace.get_tracer_provider()
+ sampler = getattr(provider, "sampler", None)
+ if sampler is not None:
+ result = sampler.should_sample(
+ parent_context=None, # root decision
+ trace_id=trace_id,
+ name="dag_run",
+ )
+ sampled = result.decision == Decision.RECORD_AND_SAMPLE
+ sampler_trace_state = result.trace_state
+ else:
+ # No sampler attribute means a proxy/no-op provider (otel disabled).
+ # Nothing exports in that case, so the flag is irrelevant; mirror the
+ # observable behavior of today when otel is off.
+ sampled = False
Review Comment:
Maybe I'm misunderstanding, but doesn't sampled=false mean this is filtering
out?
##########
shared/observability/src/airflow_shared/observability/traces/__init__.py:
##########
@@ -61,15 +62,51 @@ def generate_trace_id(self):
def new_dagrun_trace_carrier(task_span_detail_level=None) -> dict[str, str]:
- """Generate a fresh W3C traceparent carrier without creating a recordable
span."""
+ """
+ Generate a fresh W3C traceparent carrier without creating a recordable
span.
+
+ The SAMPLED flag is set from an honest *root* sampling decision made by the
+ configured tracer provider's sampler (driven by ``OTEL_TRACES_SAMPLER`` /
+ ``OTEL_TRACES_SAMPLER_ARG``), rather than being hardcoded. This makes the
+ carrier the single head-sampling decision point for a DAG run: every
+ downstream span (dag_run, task_run, worker) rides on this flag.
+
+ Backcompat: when ``OTEL_TRACES_SAMPLER`` is unset the SDK defaults to
+ ``parentbased_always_on`` whose root decision is ALWAYS_ON, so the flag is
+ SAMPLED and behavior is identical to the previous hardcoded value.
Review Comment:
Don't think this belongs in the doc strings, not relevant after this pr is
merged
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