WSGI: Changed default span-name, added callback to change span-name.

Signed-off-by: Emil Madsen <sovende@gmail.com>

Author: Skeen

ext/opentelemetry-ext-wsgi/src/opentelemetry/ext/wsgi/__init__.py

@@ -142,12 +142,8 @@ def add_response_attributes(
 
 
 def get_default_span_name(environ):
-    """Calculates a (generic) span name for an incoming HTTP request based on the PEP3333 conforming WSGI environ."""
-
-    # TODO: Update once
-    #  https://github.com/open-telemetry/opentelemetry-specification/issues/270
-    #  is resolved
-    return environ.get("PATH_INFO", "/")
+    """Default implementation for name_callback, returns HTTP {METHOD_NAME}."""
+    return "HTTP " + environ.get("REQUEST_METHOD")
 
 
 class OpenTelemetryMiddleware:
@@ -158,11 +154,15 @@ class OpenTelemetryMiddleware:
 
     Args:
         wsgi: The WSGI application callable to forward requests to.
+        name_callback: Callback which calculates a generic span name for an
+                       incoming HTTP request based on the PEP3333 WSGI environ.
+                       Optional: Defaults to get_default_span_name.
     """
 
-    def __init__(self, wsgi):
+    def __init__(self, wsgi, name_callback=None):
         self.wsgi = wsgi
         self.tracer = trace.tracer_source().get_tracer(__name__, __version__)
+        self.name_callback = name_callback or get_default_span_name
 
     @staticmethod
     def _create_start_response(span, start_response):
@@ -182,7 +182,7 @@ def __call__(self, environ, start_response):
         """
 
         parent_span = propagators.extract(get_header_from_environ, environ)
-        span_name = get_default_span_name(environ)
+        span_name = self.name_callback(environ)
 
         span = self.tracer.start_span(
             span_name,

ext/opentelemetry-ext-wsgi/tests/test_wsgi_middleware.py

@@ -74,7 +74,7 @@ def error_wsgi(environ, start_response):
 
 
 class TestWsgiApplication(WsgiTestBase):
-    def validate_response(self, response, error=None):
+    def validate_response(self, response, error=None, span_name="HTTP GET"):
         while True:
             try:
                 value = next(response)
@@ -95,7 +95,7 @@ def validate_response(self, response, error=None):
 
         span_list = self.memory_exporter.get_finished_spans()
         self.assertEqual(len(span_list), 1)
-        self.assertEqual(span_list[0].name, "/")
+        self.assertEqual(span_list[0].name, span_name)
         self.assertEqual(span_list[0].kind, trace_api.SpanKind.SERVER)
         self.assertEqual(
             span_list[0].attributes,
@@ -147,6 +147,17 @@ def test_wsgi_exc_info(self):
         response = app(self.environ, self.start_response)
         self.validate_response(response, error=ValueError)
 
+    def test_override_span_name(self):
+        """Test that span_names can be overwritten by our callback function."""
+        span_name = "Dymaxion"
+        def get_predefined_span_name(scope):
+            return span_name
+        app = otel_wsgi.OpenTelemetryMiddleware(
+            simple_wsgi, name_callback=get_predefined_span_name
+        )
+        response = app(self.environ, self.start_response)
+        self.validate_response(response, span_name=span_name)
+
 
 class TestWsgiAttributes(unittest.TestCase):
     def setUp(self):