Merge pull request #403 from palazzem/pyramid-distributed-tracing

[pyramid] add distributed tracing

Author: Emanuele Palazzetti

ddtrace/contrib/pyramid/__init__.py

@@ -15,6 +15,12 @@
     # use your config as normal.
     config.add_route('index', '/')
 
+Available settings are:
+
+* `datadog_trace_service`: change the `pyramid` service name
+* `datadog_trace_enabled`: sets if the Tracer is enabled or not
+* `datadog_distributed_tracing`: set it to `True` to enable Distributed Tracing
+
 If you use the 'pyramid.tweens' settings value to set the tweens for your
 application, you need to add 'ddtrace.contrib.pyramid:trace_tween_factory'
 explicitly to the list. For example::

ddtrace/contrib/pyramid/constants.py

@@ -1,3 +1,4 @@
 SETTINGS_SERVICE = 'datadog_trace_service'
 SETTINGS_TRACER = 'datadog_tracer'
 SETTINGS_TRACE_ENABLED = 'datadog_trace_enabled'
+SETTINGS_DISTRIBUTED_TRACING = 'datadog_distributed_tracing'

ddtrace/contrib/pyramid/trace.py

@@ -9,13 +9,21 @@
 # project
 import ddtrace
 from ...ext import http, AppTypes
-from .constants import SETTINGS_SERVICE, SETTINGS_TRACE_ENABLED, SETTINGS_TRACER
+from ...propagation.http import HTTPPropagator
+from .constants import (
+    SETTINGS_TRACER,
+    SETTINGS_SERVICE,
+    SETTINGS_TRACE_ENABLED,
+    SETTINGS_DISTRIBUTED_TRACING,
+)
+
 
 log = logging.getLogger(__name__)
 
 DD_TWEEN_NAME = 'ddtrace.contrib.pyramid:trace_tween_factory'
 DD_SPAN = '_datadog_span'
 
+
 def trace_pyramid(config):
     config.include('ddtrace.contrib.pyramid')
 
@@ -49,6 +57,7 @@ def trace_tween_factory(handler, registry):
     service = settings.get(SETTINGS_SERVICE) or 'pyramid'
     tracer = settings.get(SETTINGS_TRACER) or ddtrace.tracer
     enabled = asbool(settings.get(SETTINGS_TRACE_ENABLED, tracer.enabled))
+    distributed_tracing = asbool(settings.get(SETTINGS_DISTRIBUTED_TRACING, False))
 
     # set the service info
     tracer.set_service_info(
@@ -59,6 +68,12 @@ def trace_tween_factory(handler, registry):
     if enabled:
         # make a request tracing function
         def trace_tween(request):
+            if distributed_tracing:
+                propagator = HTTPPropagator()
+                context = propagator.extract(request.headers)
+                # only need to active the new context if something was propagated
+                if context.trace_id:
+                    tracer.context_provider.activate(context)
             with tracer.trace('pyramid.request', service=service, resource='404') as span:
                 setattr(request, DD_SPAN, span)  # used to find the tracer in templates
                 response = None

tests/contrib/pyramid/test_pyramid.py

@@ -3,7 +3,6 @@
 
 from nose.tools import eq_, assert_raises
 
-# project
 from ddtrace import compat
 from ddtrace.contrib.pyramid.patch import insert_tween_if_needed
 
@@ -16,6 +15,7 @@
 
 
 class PyramidBase(object):
+    """Base Pyramid test application"""
     instrument = False
 
     def setUp(self):
@@ -38,6 +38,9 @@ def get_settings(self):
     def override_settings(self, settings):
         self.create_app(settings)
 
+class PyramidTestCase(PyramidBase):
+    """Pyramid TestCase that includes tests for automatic instrumentation"""
+
     def test_200(self):
         res = self.app.get('/', status=200)
         assert b'idx' in res.body
@@ -248,7 +251,7 @@ def includeme(config):
     pass
 
 
-class TestPyramid(PyramidBase):
+class TestPyramid(PyramidTestCase):
     instrument = True
 
     def get_settings(self):
@@ -263,3 +266,30 @@ def test_tween_overridden(self):
         self.app.get('/json', status=200)
         spans = self.tracer.writer.pop()
         eq_(len(spans), 0)
+
+
+class TestPyramidDistributedTracing(PyramidBase):
+    instrument = True
+
+    def get_settings(self):
+        return {
+            'datadog_distributed_tracing': True,
+        }
+
+    def test_distributed_tracing(self):
+        # ensure the Context is properly created
+        # if distributed tracing is enabled
+        headers = {
+            'x-datadog-trace-id': '100',
+            'x-datadog-parent-id': '42',
+            'x-datadog-sampling-priority': '2',
+        }
+        res = self.app.get('/', headers=headers, status=200)
+        writer = self.tracer.writer
+        spans = writer.pop()
+        eq_(len(spans), 1)
+        # check the propagated Context
+        span = spans[0]
+        eq_(span.trace_id, 100)
+        eq_(span.parent_id, 42)
+        eq_(span.get_metric('_sampling_priority_v1'), 2)

tests/contrib/pyramid/test_pyramid_autopatch.py

@@ -13,15 +13,14 @@
 from ...test_tracer import get_dummy_tracer
 from ...util import override_global_tracer
 
-#from .test_pyramid import PyramidBase, get_app, custom_exception_view
-from .test_pyramid import PyramidBase
+from .test_pyramid import PyramidTestCase
 
 
-class TestPyramidAutopatch(PyramidBase):
+class TestPyramidAutopatch(PyramidTestCase):
     instrument = False
 
 
-class TestPyramidExplicitTweens(PyramidBase):
+class TestPyramidExplicitTweens(PyramidTestCase):
     instrument = False
 
     def get_settings(self):