Add entry point for Cloud Trace exporter to work with auto instrument…

…ation

opentelemetry-exporter-gcp-trace/setup.cfg

@@ -34,3 +34,9 @@ where = src
 
 [options.extras_require]
 test =
+
+[options.entry_points]
+opentelemetry_traces_exporter =
+    gcp_trace = opentelemetry.exporter.cloud_trace:CloudTraceSpanExporter
+opentelemetry_environment_variables =
+    gcp_trace = opentelemetry.exporter.cloud_trace.environment_variables

opentelemetry-exporter-gcp-trace/src/opentelemetry/exporter/cloud_trace/__init__.py

@@ -44,13 +44,36 @@
 :class:`opentelemetry.sdk.trace.export.BatchSpanProcessor` with the
 default parameters for performance reasons.
 
+Auto-instrumentation
+--------------------
+
+This exporter can also be used with `OpenTelemetry auto-instrumentation
+<https://opentelemetry.io/docs/instrumentation/python/automatic/>`_:
+
+.. code-block:: sh
+
+    opentelemetry-instrument --traces_exporter gcp_trace <command> <args>
+
+Configuration is supported through environment variables
+(:mod:`opentelemetry.exporter.cloud_trace.environment_variables`) or the corresponding command
+line arguments to ``opentelemetry-instrument``:
+
+.. code-block:: sh
+
+    opentelemetry-instrument --traces_exporter gcp_trace \\
+        --exporter_gcp_trace_project_id my-project \\
+        <command> <args>
+
+See ``opentelemetry-instrument --help`` for all configuration options.
+
 API
 ---
 """
 
 import logging
 import re
 from collections.abc import Sequence as SequenceABC
+from os import environ
 from typing import (
     Any,
     Dict,
@@ -69,6 +92,10 @@
 from google.cloud.trace_v2 import types as trace_types
 from google.protobuf.timestamp_pb2 import Timestamp
 from google.rpc import code_pb2, status_pb2
+from opentelemetry.exporter.cloud_trace.environment_variables import (
+    OTEL_EXPORTER_GCP_TRACE_PROJECT_ID,
+    OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX,
+)
 from opentelemetry.exporter.cloud_trace.version import __version__
 from opentelemetry.sdk.resources import Resource
 from opentelemetry.sdk.trace import Event
@@ -97,11 +124,13 @@ class CloudTraceSpanExporter(SpanExporter):
     """Cloud Trace span exporter for OpenTelemetry.
 
     Args:
-        project_id: ID of the cloud project that will receive the traces.
+        project_id: GCP project ID for the project to send spans to. Alternatively, can be
+            configured with :envvar:`OTEL_EXPORTER_GCP_TRACE_PROJECT_ID`.
         client: Cloud Trace client. If not given, will be taken from gcloud
             default credentials
-        resource_regex: Resource attributes with keys matching this regex will be
-          added to exported spans as labels (default: None).
+        resource_regex: Resource attributes with keys matching this regex will be added to
+            exported spans as labels (default: None). Alternatively, can be configured with
+            :envvar:`OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX`.
     """
 
     def __init__(
@@ -112,9 +141,15 @@ def __init__(
     ):
         self.client: TraceServiceClient = client or TraceServiceClient()
         if not project_id:
-            _, self.project_id = google.auth.default()
-        else:
-            self.project_id = project_id
+            project_id = environ.get(OTEL_EXPORTER_GCP_TRACE_PROJECT_ID)
+        if not project_id:
+            _, project_id = google.auth.default()
+        self.project_id = project_id
+
+        if not resource_regex:
+            resource_regex = environ.get(
+                OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX
+            )
         self.resource_regex = (
             re.compile(resource_regex) if resource_regex else None
         )

opentelemetry-exporter-gcp-trace/src/opentelemetry/exporter/cloud_trace/environment_variables.py

@@ -0,0 +1,32 @@
+# Copyright 2022 Google LLC
+#
+# 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
+#
+#      https://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.
+
+OTEL_EXPORTER_GCP_TRACE_PROJECT_ID = "OTEL_EXPORTER_GCP_TRACE_PROJECT_ID"
+"""
+.. envvar:: OTEL_EXPORTER_GCP_TRACE_PROJECT_ID
+
+    GCP project ID for the project to send spans to. Equivalent to constructor parameter to
+    :class:`opentelemetry.exporter.cloud_trace.CloudTraceSpanExporter`.
+"""
+
+OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX = (
+    "OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX"
+)
+"""
+.. envvar:: OTEL_EXPORTER_GCP_TRACE_RESOURCE_REGEX
+
+    Resource attributes with keys matching this regex will be added to exported spans as labels
+    :class:`opentelemetry.exporter.cloud_trace.CloudTraceSpanExporter`. Equivalent to constructor parameter to
+    :class:`opentelemetry.exporter.cloud_trace.CloudTraceSpanExporter`.
+"""

opentelemetry-exporter-gcp-trace/tests/test_cloud_trace_auto_instrument.py

@@ -0,0 +1,32 @@
+# Copyright 2022 Google LLC
+#
+# 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
+#
+#      https://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.
+
+from unittest import TestCase
+
+from opentelemetry.exporter.cloud_trace import CloudTraceSpanExporter
+
+# private import for testing only
+from opentelemetry.sdk._configuration import _import_exporters
+
+
+class TestCloudTraceAutoInstrument(TestCase):
+    def test_loads_cloud_trace_exporter(self):
+        """Test that OTel configuration internals can load the trace exporter from entrypoint
+        by name"""
+        trace_exporters, _ = _import_exporters(
+            trace_exporter_names=["gcp_trace"], log_exporter_names=[]
+        )
+        self.assertEquals(
+            trace_exporters, {"gcp_trace": CloudTraceSpanExporter}
+        )