durable: extract trace context from checkpoints

datadog_lambda/tracing.py

@@ -61,6 +61,7 @@
 DD_TRACE_JAVA_TRACE_ID_PADDING = "00000000"
 HIGHER_64_BITS = "HIGHER_64_BITS"
 LOWER_64_BITS = "LOWER_64_BITS"
+_TRACE_CHECKPOINT_PREFIX = "_datadog_"
 
 
 def _dsm_set_checkpoint(context_json, event_type, arn):
@@ -546,6 +547,121 @@ def extract_context_from_step_functions(event, lambda_context):
         return extract_context_from_lambda_context(lambda_context)
 
 
+def _durable_operations(event):
+    if not isinstance(event, dict):
+        return []
+
+    operations = event.get("InitialExecutionState", {}).get("Operations")
+    if isinstance(operations, list):
+        return operations
+    if not isinstance(operations, dict):
+        return []
+
+    numeric_keys = []
+    other_keys = []
+    for key, value in operations.items():
+        if not isinstance(value, dict):
+            continue
+        try:
+            numeric_keys.append((int(key), value))
+        except (TypeError, ValueError):
+            other_keys.append((str(key), value))
+
+    numeric_keys.sort(key=lambda item: item[0])
+    other_keys.sort(key=lambda item: item[0])
+    return [value for _, value in numeric_keys + other_keys]
+
+
+def _extract_context_from_durable_checkpoint(operation):
+    if not isinstance(operation, dict):
+        return None
+
+    step_details = operation.get("StepDetails")
+    if not isinstance(step_details, dict):
+        return None
+
+    result = step_details.get("Result")
+    if isinstance(result, str):
+        try:
+            result = json.loads(result)
+        except Exception:
+            return None
+
+    if not isinstance(result, dict):
+        return None
+
+    return propagator.extract(result)
+
+
+def _extract_context_from_durable_input_payload(operation):
+    if not isinstance(operation, dict):
+        return None
+
+    execution_details = operation.get("ExecutionDetails")
+    if not isinstance(execution_details, dict):
+        return None
+
+    input_payload = execution_details.get("InputPayload")
+    if isinstance(input_payload, str):
+        try:
+            input_payload = json.loads(input_payload)
+        except Exception:
+            return None
+
+    if not isinstance(input_payload, dict):
+        return None
+
+    headers = input_payload.get("headers")
+    if isinstance(headers, dict):
+        return propagator.extract(headers)
+
+    dd_data = input_payload.get("_datadog")
+    if isinstance(dd_data, dict):
+        return propagator.extract(dd_data)
+
+    return None
+
+
+def extract_context_from_durable_execution(event):
+    if not isinstance(event, dict):
+        return None
+    if not isinstance(event.get("DurableExecutionArn"), str):
+        return None
+
+    operations = _durable_operations(event)
+    if not operations:
+        return None
+
+    best_context = None
+    best_number = -1
+    for operation in operations:
+        if not isinstance(operation, dict):
+            continue
+        name = operation.get("Name")
+        if not isinstance(name, str) or not name.startswith(_TRACE_CHECKPOINT_PREFIX):
+            continue
+        suffix = name[len(_TRACE_CHECKPOINT_PREFIX) :]
+        try:
+            number = int(suffix)
+        except (TypeError, ValueError):
+            continue
+        if number < best_number:
+            continue
+        context = _extract_context_from_durable_checkpoint(operation)
+        if _is_context_complete(context):
+            best_context = context
+            best_number = number
+
+    if best_context is not None:
+        return best_context
+
+    upstream_context = _extract_context_from_durable_input_payload(operations[0])
+    if _is_context_complete(upstream_context):
+        return upstream_context
+
+    return None
+
+
 def extract_context_custom_extractor(extractor, event, lambda_context):
     """
     Extract Datadog trace context using a custom trace extractor function
@@ -633,29 +749,34 @@ def extract_dd_trace_context(
     global dd_trace_context
     trace_context_source = None
     event_source = parse_event_source(event)
+    context = None
 
     if extractor is not None:
         context = extract_context_custom_extractor(extractor, event, lambda_context)
-    elif isinstance(event, (set, dict)) and "request" in event:
-        context = extract_context_from_request_header_or_context(
-            event, lambda_context, event_source
-        )
-    elif isinstance(event, (set, dict)) and "headers" in event:
-        context = extract_context_from_http_event_or_context(
-            event, lambda_context, event_source, decode_authorizer_context
-        )
-    elif event_source.equals(EventTypes.SNS) or event_source.equals(EventTypes.SQS):
-        context = extract_context_from_sqs_or_sns_event_or_context(
-            event, lambda_context, event_source
-        )
-    elif event_source.equals(EventTypes.EVENTBRIDGE):
-        context = extract_context_from_eventbridge_event(event, lambda_context)
-    elif event_source.equals(EventTypes.KINESIS):
-        context = extract_context_from_kinesis_event(event, lambda_context)
-    elif event_source.equals(EventTypes.STEPFUNCTIONS):
-        context = extract_context_from_step_functions(event, lambda_context)
-    else:
-        context = extract_context_from_lambda_context(lambda_context)
+    elif isinstance(event, (set, dict)) and "DurableExecutionArn" in event:
+        context = extract_context_from_durable_execution(event)
+
+    if context is None:
+        if isinstance(event, (set, dict)) and "request" in event:
+            context = extract_context_from_request_header_or_context(
+                event, lambda_context, event_source
+            )
+        elif isinstance(event, (set, dict)) and "headers" in event:
+            context = extract_context_from_http_event_or_context(
+                event, lambda_context, event_source, decode_authorizer_context
+            )
+        elif event_source.equals(EventTypes.SNS) or event_source.equals(EventTypes.SQS):
+            context = extract_context_from_sqs_or_sns_event_or_context(
+                event, lambda_context, event_source
+            )
+        elif event_source.equals(EventTypes.EVENTBRIDGE):
+            context = extract_context_from_eventbridge_event(event, lambda_context)
+        elif event_source.equals(EventTypes.KINESIS):
+            context = extract_context_from_kinesis_event(event, lambda_context)
+        elif event_source.equals(EventTypes.STEPFUNCTIONS):
+            context = extract_context_from_step_functions(event, lambda_context)
+        else:
+            context = extract_context_from_lambda_context(lambda_context)
 
     if _is_context_complete(context):
         logger.debug("Extracted Datadog trace context from event or context")

tests/test_tracing.py

@@ -394,6 +394,72 @@ def test_with_w3c_trace_headers(self):
             headers, {"headers": headers}
         )
 
+    @with_trace_propagation_style("datadog")
+    def test_extracts_durable_trace_context_from_latest_checkpoint_operation_map(self):
+        lambda_ctx = get_mock_context()
+        headers = {
+            TraceHeader.TRACE_ID: "123",
+            TraceHeader.PARENT_ID: "321",
+            TraceHeader.SAMPLING_PRIORITY: "1",
+        }
+
+        event = {
+            "DurableExecutionArn": "arn:aws:lambda:us-east-2:123456789012:function:demo:1/durable-execution/demo/abc",
+            "CheckpointToken": "token",
+            "InitialExecutionState": {
+                "Operations": {
+                    "0": {
+                        "Type": "EXECUTION",
+                        "ExecutionDetails": {
+                            "InputPayload": {"order_id": "ORD-300"}
+                        },
+                    },
+                    "1": {
+                        "Name": "_datadog_0",
+                        "StepDetails": {"Result": {TraceHeader.TRACE_ID: "999"}},
+                    },
+                    "2": {
+                        "Name": "_datadog_1",
+                        "StepDetails": {"Result": headers},
+                    },
+                }
+            },
+        }
+
+        ctx, source, _ = extract_dd_trace_context(event, lambda_ctx)
+
+        self.assertEqual(source, "event")
+        self.assertEqual(ctx, Context(trace_id=123, span_id=321, sampling_priority=1))
+
+    @with_trace_propagation_style("datadog")
+    def test_extracts_durable_trace_context_from_input_payload_when_no_checkpoint(self):
+        lambda_ctx = get_mock_context()
+        headers = {
+            TraceHeader.TRACE_ID: "777",
+            TraceHeader.PARENT_ID: "888",
+            TraceHeader.SAMPLING_PRIORITY: "1",
+        }
+
+        event = {
+            "DurableExecutionArn": "arn:aws:lambda:us-east-2:123456789012:function:demo:1/durable-execution/demo/first",
+            "CheckpointToken": "token",
+            "InitialExecutionState": {
+                "Operations": {
+                    "0": {
+                        "Type": "EXECUTION",
+                        "ExecutionDetails": {
+                            "InputPayload": json.dumps({"headers": headers})
+                        },
+                    }
+                }
+            },
+        }
+
+        ctx, source, _ = extract_dd_trace_context(event, lambda_ctx)
+
+        self.assertEqual(source, "event")
+        self.assertEqual(ctx, Context(trace_id=777, span_id=888, sampling_priority=1))
+
     @with_trace_propagation_style("datadog")
     def test_with_extractor_function(self):
         def extractor_foo(event, context):