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fix: negative duration on aws.apigateway.authorizer span #782

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Merged
pablomartinezbernardo merged 2 commits into from
Apr 6, 2026
+39 −11
Merged

fix: negative duration on aws.apigateway.authorizer span #782

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Fix negative duration on aws.apigateway.authorizer span
pablomartinezbernardo Apr 6, 2026
297ab78
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pablomartinezbernardo Apr 6, 2026
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16 changes: 6 additions & 10 deletions datadog_lambda/tracing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -977,16 +977,12 @@ def process_injected_data(event, request_time_epoch_ms, args, tags):
start_time_ns = int(
injected_authorizer_data.get(Headers.Parent_Span_Finish_Time)
)
finish_time_ns = (
request_time_epoch_ms
+ (
int(
event["requestContext"]["authorizer"].get(
"integrationLatency", 0
)
)
)
) * 1e6
integration_latency = int(
event["requestContext"]["authorizer"].get("integrationLatency", 0)
)
finish_time_ns = max(
start_time_ns, (request_time_epoch_ms + integration_latency) * 1e6
)
upstream_authorizer_span = insert_upstream_authorizer_span(
args, tags, start_time_ns, finish_time_ns
)
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2 changes: 1 addition & 1 deletion tests/event_samples/authorizer-request-api-gateway-v1.json
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Original file line number Diff line number Diff line change
Expand Up @@ -55,7 +55,7 @@
"requestContext": {
"resourceId": "0et54l",
"authorizer": {
"_datadog": "eyJ4LWRhdGFkb2ctdHJhY2UtaWQiOiAiMTM0Nzg3MDU5OTU3OTcyMjEyMDkiLCAieC1kYXRhZG9nLXBhcmVudC1pZCI6ICI4NDcxMjg4MjYzMzg0MjE2ODk2IiwgIngtZGF0YWRvZy1zYW1wbGluZy1wcmlvcml0eSI6ICIxIiwgIngtZGF0YWRvZy1wYXJlbnQtc3Bhbi1maW5pc2gtdGltZSI6IDE2NjMyOTUwMjE4MjcuNTIxLCAieC1kYXRhZG9nLWF1dGhvcml6aW5nLXJlcXVlc3RpZCI6ICJhYmMxMjMifQ==",
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@pablomartinezbernardo pablomartinezbernardo Apr 6, 2026

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{
   "x-datadog-trace-id":"13478705995797221209",
   "x-datadog-parent-id":"8471288263384216896",
   "x-datadog-sampling-priority":"1",
   "x-datadog-parent-span-finish-time":1663295021827.521,
   "x-datadog-authorizing-requestid":"abc123"
}

"_datadog": "eyJ4LWRhdGFkb2ctdHJhY2UtaWQiOiAiMTM0Nzg3MDU5OTU3OTcyMjEyMDkiLCAieC1kYXRhZG9nLXBhcmVudC1pZCI6ICI4NDcxMjg4MjYzMzg0MjE2ODk2IiwgIngtZGF0YWRvZy1zYW1wbGluZy1wcmlvcml0eSI6ICIxIiwgIngtZGF0YWRvZy1wYXJlbnQtc3Bhbi1maW5pc2gtdGltZSI6IDE2NjMyOTUwMjE4Mjc1MjEwMDAsICJ4LWRhdGFkb2ctYXV0aG9yaXppbmctcmVxdWVzdGlkIjogImFiYzEyMyJ9",
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@pablomartinezbernardo pablomartinezbernardo Apr 6, 2026

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{
   "x-datadog-trace-id":"13478705995797221209",
   "x-datadog-parent-id":"8471288263384216896",
   "x-datadog-sampling-priority":"1",
   "x-datadog-parent-span-finish-time":1663295021827521000,
   "x-datadog-authorizing-requestid":"abc123"
}

"scope": "this is just a string",
"principalId": "foo",
"integrationLatency": 1897
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32 changes: 32 additions & 0 deletions tests/test_tracing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2408,6 +2408,38 @@ def test_create_inferred_span(mock_span_finish, source, expect):
assert mock_span_finish.call_count == 0


@patch("ddtrace.trace.Span.finish", autospec=True)
def test_authorizer_span_no_negative_duration_when_clock_skew(mock_span_finish):
"""
Simulate the case where requestTimeEpoch + integrationLatency < parentSpanFinishTime
(i.e., API Gateway's reported end is before the authorizer lambda's self-reported finish).
This 1ms discrepancy would produce a negative duration.
"""
with open(f"{event_samples}authorizer-request-api-gateway-v1.json") as f:
event = json.load(f)

authorizer_ctx = json.loads(
base64.b64decode(event["requestContext"]["authorizer"]["_datadog"])
)
parent_finish_time_ns = authorizer_ctx["x-datadog-parent-span-finish-time"]
request_time_epoch_ms = event["requestContext"]["requestTimeEpoch"]
# Set integrationLatency 1ms below the parent span's finish time to simulate clock skew.
event["requestContext"]["authorizer"]["integrationLatency"] = (
parent_finish_time_ns // 1_000_000 - request_time_epoch_ms - 1
)

ctx = get_mock_context(aws_request_id="123")
create_inferred_span(event, ctx)

args = mock_span_finish.call_args_list[0].args
authorizer_span, finish_time = args[0], args[1]

assert finish_time >= authorizer_span.start, (
f"Authorizer span has negative duration: "
f"finish_time={finish_time} < start={authorizer_span.start}"
)


class TestInferredSpans(unittest.TestCase):
@patch("datadog_lambda.tracing.submit_errors_metric")
def test_mark_trace_as_error_for_5xx_responses_getting_400_response_code(
Expand Down
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