Merge pull request #7 from DataDog/darcy.rayner/case-insensitive-trace-headers

Guarantee trace headers will always be treated with case insensitivity

Author: DarcyRaynerDD

datadog_lambda/tracing.py

@@ -27,9 +27,11 @@ def extract_dd_trace_context(event):
     """
     global dd_trace_context
     headers = event.get('headers', {})
-    trace_id = headers.get(TraceHeader.TRACE_ID)
-    parent_id = headers.get(TraceHeader.PARENT_ID)
-    sampling_priority = headers.get(TraceHeader.SAMPLING_PRIORITY)
+    lowercase_headers = {k.lower(): v for k, v in headers.items()}
+
+    trace_id = lowercase_headers.get(TraceHeader.TRACE_ID)
+    parent_id = lowercase_headers.get(TraceHeader.PARENT_ID)
+    sampling_priority = lowercase_headers.get(TraceHeader.SAMPLING_PRIORITY)
     if trace_id and parent_id and sampling_priority:
         dd_trace_context = {
             'trace-id': trace_id,

tests/test_tracing.py

@@ -88,6 +88,23 @@ def test_with_complete_datadog_trace_headers(self):
             XraySubsegment.NAMESPACE
         )
 
+    def test_with_complete_datadog_trace_headers_with_mixed_casing(self):
+        extract_dd_trace_context({
+            'headers': {
+                'X-Datadog-Trace-Id': '123',
+                'X-Datadog-Parent-Id': '321',
+                'X-Datadog-Sampling-Priority': '1',
+            }
+        })
+        self.assertDictEqual(
+            get_dd_trace_context(),
+            {
+                TraceHeader.TRACE_ID: '123',
+                TraceHeader.PARENT_ID: '65535',
+                TraceHeader.SAMPLING_PRIORITY: '1',
+            }
+        )
+
 
 class TestXRayContextConversion(unittest.TestCase):