feat: added google_cloud_trace_context propagator

.cspell.yml

@@ -82,3 +82,4 @@ words:
   - webmocks
   - Xuan
   - yardoc
+  - traceparent

.github/workflows/ci-contrib.yml

@@ -69,6 +69,7 @@ jobs:
           - ottrace
           - vitess
           - xray
+          - google_cloud
         os:
           - ubuntu-latest
     name: "propagator-${{ matrix.gem }} / ${{ matrix.os }}"

CONTRIBUTING.md

@@ -71,6 +71,7 @@ This repository contains multiple Ruby gems:
 * Various resource detector gems located in subdirectories of `resources`
 * `opentelemetry-propagator-xray` located in the `propagator/xray` directory
 * `opentelemetry-propagator-ottrace` located in the `propagator/ottrace` directory
+* `opentelemetry-propagator-google_cloud_trace_context` located in the `propagator/google_cloud_trace_context` directory
 
 Each of these gems has its configuration and tests.
 

propagator/google_cloud_trace_context/.rubocop.yml

@@ -0,0 +1 @@
+inherit_from: ../../.rubocop.yml

propagator/google_cloud_trace_context/.yardopts

@@ -0,0 +1,9 @@
+--no-private
+--title=OpenTelemetry Propagator Google Cloud Trace Context
+--markup=markdown
+--main=README.md
+./lib/opentelemetry/propagator/google_cloud_trace_context/**/*.rb
+./lib/opentelemetry/propagator/google_cloud_trace_context.rb
+-
+README.md
+CHANGELOG.md

propagator/google_cloud_trace_context/CHANGELOG.md

@@ -0,0 +1 @@
+# Release History: opentelemetry-propagator-google_cloud_trace_context

propagator/google_cloud_trace_context/Gemfile

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gemspec
+
+group :test do
+  if RUBY_VERSION >= '3.4'
+    gem 'mutex_m'
+  end
+end

propagator/google_cloud_trace_context/LICENSE

@@ -0,0 +1,201 @@
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propagator/google_cloud_trace_context/README.md

@@ -0,0 +1,71 @@
+# opentelemetry-propagator-google_cloud_trace_context
+
+The `opentelemetry-propagator-google_cloud_trace_context` gem contains injectors and extractors for the
+[Google Cloud X-Cloud-Trace-Context format][gcp-spec].
+
+## X-Cloud-Trace-Context header
+
+The `X-Cloud-Trace-Context` header that is used by Google Cloud predates the W3C specification. For backwards compatibility, some Google Cloud services continue to accept, generate, and propagate the `X-Cloud-Trace-Context` header. However, it is likely that these systems also support the traceparent header.
+
+For example Google's Cloud Load Balancers (which do not support the traceparent header)[https://issuetracker.google.com/issues/253419736], instead will only propagate `X-Cloud-Trace-Context` which this gem helps resolve.
+
+The `X-Cloud-Trace-Context` header has the following format:
+
+```yaml
+X-Cloud-Trace-Context: TRACE_ID/SPAN_ID;o=OPTIONS
+```
+
+The fields of header are defined as follows:
+
+- `TRACE_ID` is a 32-character hexadecimal value representing a 128-bit number.
+- `SPAN_ID` is a 64-bit decimal representation of the unsigned span ID.
+- `OPTIONS` supports 0 (parent not sampled) and 1 (parent was sampled).
+
+## What is OpenTelemetry?
+
+[OpenTelemetry][opentelemetry-home] is an open source observability framework, providing a general-purpose API, SDK, and related tools required for the instrumentation of cloud-native software, frameworks, and libraries.
+
+OpenTelemetry provides a single set of APIs, libraries, agents, and collector services to capture distributed traces and metrics from your application. You can analyze them using Prometheus, Jaeger, and other observability tools.
+
+## How does this gem fit in?
+
+This gem can be used with any OpenTelemetry SDK implementation. This can be the official `opentelemetry-sdk` gem or any other concrete implementation.
+
+## How do I get started?
+
+Install the gem using:
+
+```console
+gem install opentelemetry-propagator-google_cloud_trace_context
+```
+
+Or, if you use [bundler][bundler-home], include `opentelemetry-propagator-google_cloud_trace_context` in your `Gemfile`.
+
+Configure your application to use this propagator by setting the following [environment variable][envars]:
+
+```console
+OTEL_PROPAGATORS=google_cloud_trace_context
+```
+
+## How can I get involved?
+
+The `opentelemetry-propagator-google_cloud_trace_context` gem source is [on github][repo-github], along with related gems including `opentelemetry-api` and `opentelemetry-sdk`.
+
+The OpenTelemetry Ruby gems are maintained by the OpenTelemetry Ruby special interest group (SIG). You can get involved by joining us on our [GitHub Discussions][discussions-url], [Slack Channel][slack-channel] or attending our weekly meeting. See the [meeting calendar][community-meetings] for dates and times. For more information on this and other language SIGs, see the OpenTelemetry [community page][ruby-sig].
+
+## License
+
+The `opentelemetry-propagator-google_cloud_trace_context` gem is distributed under the Apache 2.0 license. See [LICENSE][license-github] for more information.
+
+[opentelemetry-home]: https://opentelemetry.io
+[bundler-home]: https://bundler.io
+[repo-github]: https://github.com/open-telemetry/opentelemetry-ruby
+[license-github]: https://github.com/open-telemetry/opentelemetry-ruby-contrib/blob/main/LICENSE
+[ruby-sig]: https://github.com/open-telemetry/community#ruby-sig
+[community-meetings]: https://github.com/open-telemetry/community#community-meetings
+[slack-channel]: https://cloud-native.slack.com/archives/C01NWKKMKMY
+[discussions-url]: https://github.com/open-telemetry/opentelemetry-ruby/discussions
+[gcp-spec]: https://cloud.google.com/appengine/docs/standard/writing-application-logs
+[rfc7230-url]: https://tools.ietf.org/html/rfc7230#section-3.2
+[fields-spec-url]: https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/context/api-propagators.md#fields
+[envars]: https://github.com/open-telemetry/opentelemetry-specification/blob/v1.20.0/specification/sdk-environment-variables.md#general-sdk-configuration

propagator/google_cloud_trace_context/Rakefile

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'bundler/gem_tasks'
+require 'rake/testtask'
+require 'yard'
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new
+
+Rake::TestTask.new :test do |t|
+  t.libs << 'test'
+  t.libs << 'lib'
+  t.test_files = FileList['test/**/*_test.rb']
+end
+
+YARD::Rake::YardocTask.new do |t|
+  t.stats_options = ['--list-undoc']
+end
+
+if RUBY_ENGINE == 'truffleruby'
+  task default: %i[test]
+else
+  task default: %i[test rubocop yard]
+end

propagator/google_cloud_trace_context/lib/opentelemetry-propagator-google_cloud_trace_context.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'opentelemetry-api'
+require_relative 'opentelemetry/propagator/google_cloud_trace_context'

propagator/google_cloud_trace_context/lib/opentelemetry/propagator/google_cloud_trace_context.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'opentelemetry/propagator/google_cloud_trace_context/version'
+require 'opentelemetry/propagator/google_cloud_trace_context/text_map_propagator'
+
+# OpenTelemetry is an open source observability framework, providing a
+# general-purpose API, SDK, and related tools required for the instrumentation
+# of cloud-native software, frameworks, and libraries.
+#
+# The OpenTelemetry module provides global accessors for telemetry objects.
+# See the documentation for the `opentelemetry-api` gem for details.
+module OpenTelemetry
+  # Namespace for OpenTelemetry propagator extension libraries
+  module Propagator
+    # Namespace for OpenTelemetry GoogleCloudTraceContext propagation
+    module GoogleCloudTraceContext
+      extend self
+
+      TEXT_MAP_PROPAGATOR = TextMapPropagator.new
+
+      private_constant :TEXT_MAP_PROPAGATOR
+
+      # Returns a text map propagator that propagates context using the
+      # GoogleCloudTraceContext format.
+      def text_map_propagator
+        TEXT_MAP_PROPAGATOR
+      end
+    end
+  end
+end