Opencensus exporters should populate service_name from Span Resource

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.3.0-0.22b0...HEAD)
 
+### Changed
+- Updated `opentelemetry-opencensus-exporter` to use `service_name` of spans instead of resource
+  ([#1854](https://github.com/open-telemetry/opentelemetry-python/pull/1854))
+
 ## [1.3.0-0.22b0](https://github.com/open-telemetry/opentelemetry-python/releases/tag/v1.3.0-0.22b0) - 2021-06-01
 
 ### Added 

exporter/opentelemetry-exporter-opencensus/src/opentelemetry/exporter/opencensus/trace_exporter/__init__.py

@@ -66,9 +66,19 @@ def __init__(
         else:
             self.client = client
 
+        self.host_name = host_name
         self.node = utils.get_node(service_name, host_name)
 
     def export(self, spans: Sequence[ReadableSpan]) -> SpanExportResult:
+        # Populate service_name from first span
+        # We restrict any SpanProcessor to be only associated with a single
+        # TracerProvider, so it is safe to assume that all Spans in a single
+        # batch all originate from one TracerProvider (and in turn have all
+        # the same service_name)
+        if spans:
+            service_name = spans[0].resource.attributes.get(SERVICE_NAME)
+            if service_name:
+                self.node = utils.get_node(service_name, self.host_name)
         try:
             responses = self.client.Export(self.generate_span_requests(spans))
 

exporter/opentelemetry-exporter-opencensus/tests/test_otcollector_trace_exporter.py

@@ -14,6 +14,7 @@
 
 import unittest
 from unittest import mock
+from unittest.mock import patch
 
 import grpc
 from google.protobuf.timestamp_pb2 import Timestamp
@@ -34,6 +35,8 @@
 
 # pylint: disable=no-member
 class TestCollectorSpanExporter(unittest.TestCase):
+
+    @patch("opentelemetry.exporter.opencensus.trace_exporter.trace._TRACER_PROVIDER", None)
     def test_constructor(self):
         mock_get_node = mock.Mock()
         patch = mock.patch(
@@ -324,3 +327,41 @@ def test_export(self):
         self.assertEqual(
             getattr(output_identifier, "host_name"), "testHostName"
         )
+
+    @patch("opentelemetry.exporter.opencensus.trace_exporter.trace._TRACER_PROVIDER", None)
+    def test_export_service_name(self):
+        trace_api.set_tracer_provider(
+            TracerProvider(
+                resource=Resource.create({SERVICE_NAME: "testServiceName"})
+            )
+        )
+        mock_client = mock.MagicMock()
+        mock_export = mock.MagicMock()
+        mock_client.Export = mock_export
+        host_name = "testHostName"
+        collector_exporter = OpenCensusSpanExporter(
+            client=mock_client, host_name=host_name
+        )
+        self.assertEqual(collector_exporter.node.service_info.name, "testServiceName")
+
+        trace_id = 0x6E0C63257DE34C926F9EFCD03927272E
+        span_id = 0x34BF92DEEFC58C92
+        span_context = trace_api.SpanContext(
+            trace_id,
+            span_id,
+            is_remote=False,
+            trace_flags=TraceFlags(TraceFlags.SAMPLED),
+        )
+        resource = Resource.create({SERVICE_NAME: "test"})
+        otel_spans = [
+            trace._Span(
+                name="test1",
+                context=span_context,
+                kind=trace_api.SpanKind.CLIENT,
+                resource=resource,
+            )
+        ]
+
+        result_status = collector_exporter.export(otel_spans)
+        self.assertEqual(SpanExportResult.SUCCESS, result_status)
+        self.assertEqual(collector_exporter.node.service_info.name, "test")