feat: [SVLS-5677] DynamoDB Stream event span pointers

Author: apiarian-datadog

datadog_lambda/span_pointers.py

@@ -2,6 +2,9 @@
 import logging
 from typing import List
 
+from ddtrace._trace.utils_botocore.span_pointers.dynamodb import (
+ _aws_dynamodb_item_span_pointer_description,
+)
 from ddtrace._trace.utils_botocore.span_pointers.s3 import (
  _aws_s3_object_span_pointer_description,
 )
@@ -21,6 +24,9 @@ def calculate_span_pointers(
  if event_source.equals(EventTypes.S3):
  return _calculate_s3_span_pointers_for_event(event)
 
+ elif event_source.equals(EventTypes.DYNAMODB):
+ return _calculate_dynamodb_span_pointers_for_event(event)
+
  except Exception as e:
  logger.warning(
  "failed to calculate span pointers for event: %s",
@@ -89,3 +95,64 @@ def _calculate_s3_span_pointers_for_object_created_s3_information(
  str(e),
  )
  return []
+
+
+def _calculate_dynamodb_span_pointers_for_event(event) -> List[_SpanPointerDescription]:
+ # Example event:
+ # https://docs.aws.amazon.com/lambda/latest/dg/with-ddb.html
+
+ return list(
+ chain.from_iterable(
+ _calculate_dynamodb_span_pointers_for_event_record(record)
+ for record in event.get("Records", [])
+ )
+ )
+
+
+def _calculate_dynamodb_span_pointers_for_event_record(
+ record,
+) -> List[_SpanPointerDescription]:
+ try:
+ table_name = _extract_table_name_from_dynamodb_stream_record(record)
+ primary_key = record["dynamodb"]["Keys"]
+
+ except Exception as e:
+ logger.warning(
+ "missing DynamoDB information required to make a span pointer: %s",
+ str(e),
+ )
+ return []
+
+ try:
+ return [
+ _aws_dynamodb_item_span_pointer_description(
+ pointer_direction=_SpanPointerDirection.UPSTREAM,
+ table_name=table_name,
+ primary_key=primary_key,
+ )
+ ]
+
+ except Exception as e:
+ logger.warning(
+ "failed to generate DynamoDB span pointer: %s",
+ str(e),
+ )
+ return []
+
+
+def _extract_table_name_from_dynamodb_stream_record(record) -> str:
+ # Example eventSourceARN:
+ # arn:aws:dynamodb:us-east-2:123456789012:table/my-table/stream/2024-06-10T19:26:16.525
+ event_source_arn = record["eventSourceARN"]
+
+ [_arn, _aws, _dynamodb, _region, _account, dynamodb_info] = event_source_arn.split(
+ ":", maxsplit=5
+ )
+ if _arn != "arn" or _aws != "aws" or _dynamodb != "dynamodb":
+ raise ValueError(f"unexpected eventSourceARN format: {event_source_arn}")
+
+ [_table, table_name, _stream, _timestamp] = dynamodb_info.split("/")
+ if not _table == "table" or not _stream == "stream":
+ raise ValueError(f"unexpected eventSourceARN format: {event_source_arn}")
+
+ return table_name

tests/test_span_pointers.py

@@ -80,6 +80,67 @@ class SpanPointersCase(NamedTuple):
  },
  span_pointers=[],
  ),
+ SpanPointersCase(
+ name="empty dynamodb event",
+ event_source=_EventSource(EventTypes.DYNAMODB),
+ event={},
+ span_pointers=[],
+ ),
+ SpanPointersCase(
+ name="sensible dynamodb event",
+ event_source=_EventSource(EventTypes.DYNAMODB),
+ event={
+ "Records": [
+ {
+ "eventSourceARN": "arn:aws:dynamodb:us-west-2:123456789012:table/some-table/stream/2015-06-27T00:48:05.899",
+ "dynamodb": {
+ "Keys": {
+ "some-key": {"S": "some-value"},
+ },
+ },
+ },
+ {
+ "eventSourceARN": "arn:aws:dynamodb:us-west-2:123456789012:table/some-table/stream/2015-06-27T00:48:05.899",
+ "dynamodb": {
+ "Keys": {
+ "some-key": {"S": "some-other-value"},
+ },
+ },
+ },
+ ],
+ },
+ span_pointers=[
+ _SpanPointerDescription(
+ pointer_kind="aws.dynamodb.item",
+ pointer_direction=_SpanPointerDirection.UPSTREAM,
+ pointer_hash="7f1aee721472bcb48701d45c7c7f7821",
+ extra_attributes={},
+ ),
+ _SpanPointerDescription(
+ pointer_kind="aws.dynamodb.item",
+ pointer_direction=_SpanPointerDirection.UPSTREAM,
+ pointer_hash="36b820424312a6069bd3f2185f1af584",
+ extra_attributes={},
+ ),
+ ],
+ ),
+ SpanPointersCase(
+ name="malformed dynamodb event",
+ event_source=_EventSource(EventTypes.DYNAMODB),
+ event={
+ "Records": [
+ {
+ "eventSourceARN": "arn:aws:dynamodb:us-west-2:123456789012:table/some-table", # missing stream info
+ "dynamodb": {
+ "Keys": {
+ "some-key": {"S": "some-value"},
+ },
+ },
+ },
+ ],
+ },
+ span_pointers=[],
+ ),
  ],
  ids=lambda test_case: test_case.name,
  )