Add grpc trace export sample (#316)

* update python version

* Add sample that uses gRPC to export traces

* Fix grpc auto-refresh token

* Remove debug logging statements

* Revert python version to avoid failing CI lint checks

* Rename example-grpc.py → example_grpc.py

* Fix formatting using isort and black

* Fix formatting in http sample

* Simplify AuthMetadataPlugin implementation

The default implementation was not working earlier because the
x-goog-user-project was being set by the code as well as gRPC. Resulting in
duplicating the header. This caused value of the project name to be
repeated, resulting in a project ID that did not exist.

samples/otlptrace/README.md

@@ -0,0 +1,32 @@
+### OTLP Export Sample with GCP Auth
+This example shows how to send traces to an OTLP (OpenTelemetry Protocol) endpoint that is protected by GCP authentication. The sample showcases the trace export using:
+ - gRPC
+ - http with protobuf
+
+#### Installation
+Install the dependencies and libraries required to run the samples:
+
+```sh
+# Move to the sample repository
+cd samples/otlptrace
+
+pip install -r requirements.txt
+```
+
+#### Prerequisites
+Get Google credentials on your machine:
+
+```sh
+gcloud auth application-default login
+```
+
+#### Run the Sample
+```sh
+# export necessary OTEL environment variables
+export OTEL_RESOURCE_ATTRIBUTES="gcp.project_id=<project-id>"
+export OTEL_EXPORTER_OTLP_ENDPOINT=<endpoint>
+
+cd samples/otlptrace && python3 example_grpc.py
+```
+Other variations of the sample:
+ - `python3 example_http.py` - will run a program that will export traces using http/protobuf.

samples/otlptrace/example_grpc.py

@@ -0,0 +1,74 @@
+#!/usr/bin/env python3
+# Copyright 2024 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
+#
+#     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 time
+
+import google.auth
+import google.auth.transport.grpc
+import google.auth.transport.requests
+import grpc
+from google.auth.transport.grpc import AuthMetadataPlugin
+from opentelemetry import trace
+from opentelemetry.exporter.otlp.proto.grpc.trace_exporter import (
+    OTLPSpanExporter,
+)
+from opentelemetry.sdk.resources import SERVICE_NAME, Resource
+from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace.export import BatchSpanProcessor
+
+"""
+This is a sample script that exports OTLP traces encoded as protobufs via gRPC. 
+"""
+
+
+credentials, project_id = google.auth.default()
+request = google.auth.transport.requests.Request()
+credentials.refresh(request)
+resource = Resource.create(attributes={SERVICE_NAME: "otlp-gcp-grpc-sample"})
+
+auth_metadata_plugin = AuthMetadataPlugin(
+    credentials=credentials, request=request
+)
+channel_creds = grpc.composite_channel_credentials(
+    grpc.ssl_channel_credentials(),
+    grpc.metadata_call_credentials(auth_metadata_plugin),
+)
+
+trace_provider = TracerProvider(resource=resource)
+processor = BatchSpanProcessor(
+    OTLPSpanExporter(credentials=channel_creds, insecure=False)
+)
+trace_provider.add_span_processor(processor)
+trace.set_tracer_provider(trace_provider)
+tracer = trace.get_tracer("my.tracer.name")
+
+
+def do_work():
+    with tracer.start_as_current_span("span-grpc") as span:
+        # do some work that 'span' will track
+        print("doing some work...")
+        # When the 'with' block goes out of scope, 'span' is closed for you
+
+
+def do_work_repeatedly():
+    try:
+        while True:
+            do_work()
+            time.sleep(10)
+    except KeyboardInterrupt:
+        print("\nKeyboard Interrupt: Stopping work.")
+
+
+do_work_repeatedly()

samples/otlptrace/example_http.py

@@ -30,9 +30,7 @@
     "x-goog-user-project": credentials.quota_project_id,
     "Authorization": "Bearer " + credentials.token,
 }
-resource = Resource.create(attributes={
-    SERVICE_NAME: "otlp-gcp-http-sample"
-})
+resource = Resource.create(attributes={SERVICE_NAME: "otlp-gcp-http-sample"})
 
 trace_provider = TracerProvider(resource=resource)
 processor = BatchSpanProcessor(OTLPSpanExporter(headers=req_headers))

samples/otlptrace/requirements.txt

@@ -0,0 +1,7 @@
+# Dependencies require for trace export samples
+opentelemetry-api==1.24.0
+opentelemetry-sdk==1.24.0
+google-auth==2.18.1
+opentelemetry-exporter-otlp-proto-http==1.24.0
+opentelemetry-exporter-otlp-proto-grpc==1.24.0
+grpcio==1.63.0