Add faraday instrumentation adapter #67

.circleci/config.yml

@@ -15,7 +15,7 @@ executors:
       - image: "circleci/ruby:2.6-stretch"
   jruby:
     docker:
-      - image: "circleci/jruby:latest"
+      - image: "circleci/jruby:9.2.8-jre"
     environment:
       JRUBY_OPTS: "--debug"
 commands:
@@ -40,6 +40,15 @@ commands:
       - run:
           name: CI (Jaeger)
           command: "cd exporters/jaeger && bundle exec rake"
+      - run:
+          name: Bundle + CI (Adapters - Faraday)
+          command: |
+            cd adapters/faraday
+            gem uninstall -aIx bundler
+            gem install --no-document bundler -v '~> 2.0.2'
+            bundle install --jobs=3 --retry=3
+            bundle exec appraisal install
+            bundle exec appraisal rake test
   rake-release:
     steps:
       - checkout

.gitignore

@@ -4,3 +4,6 @@
 **/coverage
 **/*.gem
 **/.bundle
+
+# Appraisals
+adapters/**/*.gemfile.lock

adapters/faraday/Appraisals

@@ -0,0 +1,15 @@
+appraise "faraday-1.0" do
+  gem "faraday", "~> 1.0.0"
+end
+
+appraise "faraday-0.17" do
+  gem "faraday", "0.17.0"
+end
+
+appraise "faraday-0.16" do
+  gem "faraday", "0.16.2"
+end
+
+appraise "faraday-0.13" do
+  gem "faraday", "0.13.1"
+end

adapters/faraday/Gemfile

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+source 'https://rubygems.org'
+
+gemspec
+
+gem 'opentelemetry-api', path: '../../api'
+
+group :test do
+  gem 'opentelemetry-sdk', path: '../../sdk'
+end

adapters/faraday/Rakefile

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'bundler/gem_tasks'
+require 'rake/testtask'
+
+Rake::TestTask.new :test do |t|
+  t.libs << 'test'
+  t.libs << 'lib'
+  t.test_files = FileList['test/**/*_test.rb']
+end

adapters/faraday/example/Gemfile

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gem 'faraday'
+gem 'opentelemetry-api', path: '../../../api'
+gem 'opentelemetry-sdk', path: '../../../sdk'

adapters/faraday/example/faraday.rb

@@ -0,0 +1,31 @@
+require 'rubygems'
+require 'bundler/setup'
+
+require 'faraday'
+require 'opentelemetry/sdk'
+require_relative '../lib/opentelemetry/adapters/faraday'
+
+# Set preferred tracer implementation:
+SDK = OpenTelemetry::SDK
+
+factory = OpenTelemetry.tracer_factory = SDK::Trace::TracerFactory.new
+factory.add_span_processor(
+  SDK::Trace::Export::SimpleSpanProcessor.new(
+    SDK::Trace::Export::ConsoleSpanExporter.new
+  )
+)
+
+# Demonstrate disabling span reporting:
+#
+# require_relative '../lib/opentelemetry/adapters/faraday/middlewares/tracer_middleware'
+# class NoOp < OpenTelemetry::Adapters::Faraday::Middlewares::TracerMiddleware
+#   def disable_span_reporting?(env)
+#     env.url.to_s =~ /example.com/
+#   end
+# end
+# OpenTelemetry::Adapters::Faraday.install(tracer_middleware: NoOp)
+
+OpenTelemetry::Adapters::Faraday.install
+
+conn = Faraday.new('http://example.com')
+conn.get '/'

adapters/faraday/gemfiles/faraday_0.13.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "faraday", "0.13.1"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/faraday/gemfiles/faraday_0.16.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "faraday", "0.16.2"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/faraday/gemfiles/faraday_0.17.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "faraday", "0.17.0"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/faraday/gemfiles/faraday_1.0.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "faraday", "~> 1.0.0"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/faraday/lib/opentelemetry/adapters.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  # "Instrumentation adapters" are specified by
+  # https://github.com/open-telemetry/opentelemetry-specification/blob/57714f7547fe4dcb342ad0ad10a80d86118431c7/specification/overview.md#instrumentation-adapters
+  #
+  # Adapters should be able to handle the case when the library is not installed on a user's system.
+  module Adapters
+  end
+end

adapters/faraday/lib/opentelemetry/adapters/faraday.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Faraday
+      module_function
+
+      def install(config = {})
+        require_relative 'faraday/adapter'
+        Faraday::Adapter.install(config)
+      end
+
+      # Convenience method to access the nested module name
+      def name
+        Module.nesting[0].to_s
+      end
+
+      # Convenience method to access the adapter version
+      def version
+        VERSION
+      end
+    end
+  end
+end
+
+require_relative './faraday/version'

adapters/faraday/lib/opentelemetry/adapters/faraday/adapter.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'faraday'
+require 'opentelemetry'
+
+require_relative 'middlewares/tracer_middleware'
+require_relative 'patches/rack_builder'
+
+module OpenTelemetry
+  module Adapters
+    module Faraday
+      class Adapter
+        class << self
+          attr_reader :config,
+                      :propagator
+
+          def install(config = {})
+            @config = config
+            # allow custom middleware to override default implementation:
+            @config[:tracer_middleware] ||= Middlewares::TracerMiddleware
+            @propagator = OpenTelemetry.tracer_factory.http_text_format
+
+            new.install
+          end
+
+          def tracer
+            @tracer ||= OpenTelemetry.tracer_factory.tracer(
+              Faraday.name,
+              Faraday.version
+            )
+          end
+        end
+
+        def install
+          register_tracer_middleware
+          use_middleware_by_default
+        end
+
+        private
+
+        def register_tracer_middleware
+          ::Faraday::Middleware.register_middleware(
+            open_telemetry: self.class.config[:tracer_middleware]
+          )
+        end
+
+        def use_middleware_by_default
+          ::Faraday::RackBuilder.prepend(Patches::RackBuilder)
+        end
+      end
+    end
+  end
+end

adapters/faraday/lib/opentelemetry/adapters/faraday/middlewares/tracer_middleware.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Faraday
+      module Middlewares
+        class TracerMiddleware < ::Faraday::Middleware
+          def call(env)
+            return app.call(env) if disable_span_reporting?(env)
+
+            tracer.in_span(env.url.to_s,
+                          attributes: { 'component' => 'http',
+                                        'http.method' => env.method,
+                                        'http.url' => env.url.to_s },
+                          kind: :client) do |span|
+              propagate_context(span, env)
+
+              app.call(env).on_complete { |resp| trace_response(span, resp) }
+            end
+          end
+
+          # Override implementation (subclass) to determine per-connection
+          # span reporting rules.
+          def disable_span_reporting?(_env)
+            false
+          end
+
+          private
+
+          attr_reader :app
+
+          # Outbound requests should only need to inject the current span.
+          def propagate_context(span, env)
+            propagator.inject(span.context, env.request_headers)
+          end
+
+          def propagator
+            Faraday::Adapter.propagator
+          end
+
+          def tracer
+            Faraday::Adapter.tracer
+          end
+
+          def trace_response(span, response)
+            span.set_attribute('http.status_code', response.status)
+            span.set_attribute('http.status_text', response.reason_phrase)
+          end
+        end
+      end
+    end
+  end
+end

adapters/faraday/lib/opentelemetry/adapters/faraday/patches/rack_builder.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+require_relative '../middlewares/tracer_middleware'
+
+module OpenTelemetry
+  module Adapters
+    module Faraday
+      module Patches
+        # Module to be prepended to force Faraday to use the middleware by
+        # default so the user doesn't have to call `use` for every connection.
+        module RackBuilder
+          def adapter(*args)
+            use(:open_telemetry) unless @handlers.any? do |handler|
+              handler.klass == Faraday::Adapter.config[:tracer_middleware]
+            end
+
+            super
+          end
+        end
+      end
+    end
+  end
+end

adapters/faraday/lib/opentelemetry/adapters/faraday/version.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# Copyright 2019 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Faraday
+      VERSION = '0.0.0'
+    end
+  end
+end