api: ensure status is always string (open-telemetry#640)

Ensuring that exporters can always expect status descriptions to be a string.

This was implemented to be defensive against instrumentations such as PyMongo, which currently set status as a dict.

Co-authored-by: Mauricio Vásquez <mauricio@kinvolk.io>
Co-authored-by: Yusuke Tsutsumi <yusuke@tsutsumi.io>

ext/opentelemetry-ext-otcollector/src/opentelemetry/ext/otcollector/trace_exporter/__init__.py

@@ -98,6 +98,7 @@ def translate_to_collector(spans: Sequence[Span]):
                 code=span.status.canonical_code.value,
                 message=span.status.description,
             )
+
         collector_span = trace_pb2.Span(
             name=trace_pb2.TruncatableString(value=span.name),
             kind=utils.get_collector_span_kind(span.kind),

ext/opentelemetry-ext-otcollector/tests/test_otcollector_trace_exporter.py

@@ -154,6 +154,11 @@ def test_translate_to_collector(self):
         )
         otel_spans[0].end(end_time=end_times[0])
         otel_spans[1].start(start_time=start_times[1])
+        otel_spans[1].set_status(
+            trace_api.Status(
+                trace_api.status.StatusCanonicalCode.INTERNAL, {"test", "val"},
+            )
+        )
         otel_spans[1].end(end_time=end_times[1])
         otel_spans[2].start(start_time=start_times[2])
         otel_spans[2].end(end_time=end_times[2])
@@ -263,6 +268,10 @@ def test_translate_to_collector(self):
             output_spans[0].links.link[0].type,
             trace_pb2.Span.Link.Type.TYPE_UNSPECIFIED,
         )
+        self.assertEqual(
+            output_spans[1].status.code,
+            trace_api.status.StatusCanonicalCode.INTERNAL.value,
+        )
         self.assertEqual(
             output_spans[2].links.link[0].type,
             trace_pb2.Span.Link.Type.PARENT_LINKED_SPAN,

opentelemetry-api/src/opentelemetry/trace/status.py

@@ -13,8 +13,11 @@
 # limitations under the License.
 
 import enum
+import logging
 import typing
 
+logger = logging.getLogger(__name__)
+
 
 class StatusCanonicalCode(enum.Enum):
     """Represents the canonical set of status codes of a finished Span."""
@@ -167,7 +170,11 @@ def __init__(
         description: typing.Optional[str] = None,
     ):
         self._canonical_code = canonical_code
-        self._description = description
+        self._description = None
+        if description is not None and not isinstance(description, str):
+            logger.warning("Invalid status description type, expected str")
+        else:
+            self._description = description
 
     @property
     def canonical_code(self) -> StatusCanonicalCode:

opentelemetry-api/tests/trace/test_status.py

@@ -0,0 +1,35 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+from logging import WARNING
+
+from opentelemetry.trace.status import Status, StatusCanonicalCode
+
+
+class TestStatus(unittest.TestCase):
+    def test_constructor(self):
+        status = Status()
+        self.assertIs(status.canonical_code, StatusCanonicalCode.OK)
+        self.assertIsNone(status.description)
+
+        status = Status(StatusCanonicalCode.UNAVAILABLE, "unavailable")
+        self.assertIs(status.canonical_code, StatusCanonicalCode.UNAVAILABLE)
+        self.assertEqual(status.description, "unavailable")
+
+    def test_invalid_description(self):
+        with self.assertLogs(level=WARNING):
+            status = Status(description={"test": "val"})  # type: ignore
+            self.assertIs(status.canonical_code, StatusCanonicalCode.OK)
+            self.assertEqual(status.description, None)