Add excon instrumentation adapter

.circleci/config.yml

@@ -50,6 +50,15 @@ commands:
           command: "cd exporters/jaeger && bundle exec rake"
   rake-test-appraisal:
     steps:
+      - run:
+          name: Bundle + CI (Adapters - excon)
+          command: |
+            cd adapters/excon
+            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
       - run:
           name: Bundle + CI (Adapters - Faraday)
           command: |

Rakefile

@@ -57,6 +57,12 @@ GEM_INFO = {
       OpenTelemetry::Exporters::Jaeger::VERSION
     }
   },
+  "opentelemetry-adapters-excon" => {
+    version_getter: ->() {
+      require './lib/opentelemetry/adapters/excon/version.rb'
+      OpenTelemetry::Adapters::Excon::VERSION
+    }
+  },
   "opentelemetry-adapters-faraday" => {
     version_getter: ->() {
       require './lib/opentelemetry/adapters/faraday/version.rb'

adapters/excon/.rubocop.yml

@@ -0,0 +1,27 @@
+AllCops:
+  TargetRubyVersion: '2.4.0'
+
+Bundler/OrderedGems:
+  Exclude:
+    - gemfiles/**/*
+Lint/UnusedMethodArgument:
+  Enabled: false
+Metrics/AbcSize:
+  Max: 18
+Metrics/LineLength:
+  Enabled: false
+Metrics/MethodLength:
+  Max: 20
+Metrics/ParameterLists:
+  Enabled: false
+Naming/FileName:
+  Exclude:
+    - "lib/opentelemetry-adapters-excon.rb"
+Style/FrozenStringLiteralComment:
+  Exclude:
+    - gemfiles/**/*
+Style/ModuleFunction:
+  Enabled: false
+Style/StringLiterals:
+  Exclude:
+    - gemfiles/**/*

adapters/excon/Appraisals

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+appraise 'excon-0.71' do
+  gem 'excon', '~> 0.71.0'
+end
+
+appraise 'excon-0.64' do
+  gem 'excon', '~> 0.64.0'
+end

adapters/excon/Gemfile

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+# Copyright 2020 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/excon/Rakefile

@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+# Copyright 2020 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

adapters/excon/example/Gemfile

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+gem 'excon'
+gem 'opentelemetry-adapters-excon', path: '../../../adapters/excon'
+gem 'opentelemetry-api', path: '../../../api'
+gem 'opentelemetry-sdk', path: '../../../sdk'

adapters/excon/example/excon.rb

@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+require 'rubygems'
+require 'bundler/setup'
+
+Bundler.require
+
+OpenTelemetry::SDK.configure do |c|
+  c.use 'OpenTelemetry::Adapters::Excon'
+end
+
+Excon.get('http://example.com')

adapters/excon/gemfiles/excon_0.64.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "excon", "~> 0.64.0"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/excon/gemfiles/excon_0.71.gemfile

@@ -0,0 +1,12 @@
+# This file was generated by Appraisal
+
+source "https://rubygems.org"
+
+gem "opentelemetry-api", path: "../../../api"
+gem "excon", "~> 0.71.0"
+
+group :test do
+  gem "opentelemetry-sdk", path: "../../../sdk"
+end
+
+gemspec path: "../"

adapters/excon/lib/opentelemetry-adapters-excon.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+# Copyright 2020 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require_relative './opentelemetry/adapters'

adapters/excon/lib/opentelemetry/adapters.rb

@@ -0,0 +1,16 @@
+# frozen_string_literal: true
+
+# Copyright 2020 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
+
+require_relative './adapters/excon'

adapters/excon/lib/opentelemetry/adapters/excon.rb

@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+# Copyright 2020 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'opentelemetry'
+
+module OpenTelemetry
+  module Adapters
+    # Contains the OpenTelemetry adapter for the Excon gem
+    module Excon
+    end
+  end
+end
+
+require_relative './excon/adapter'
+require_relative './excon/version'

adapters/excon/lib/opentelemetry/adapters/excon/adapter.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+# Copyright 2020 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Excon
+      # The Adapter class contains logic to detect and install the Excon
+      # instrumentation adapter
+      class Adapter < OpenTelemetry::Instrumentation::Adapter
+        install do |_config|
+          require_dependencies
+          add_middleware
+        end
+
+        present do
+          defined?(::Excon)
+        end
+
+        private
+
+        def require_dependencies
+          require_relative 'middlewares/tracer_middleware'
+        end
+
+        def add_middleware
+          ::Excon.defaults[:middlewares] =
+            Middlewares::TracerMiddleware.around_default_stack
+        end
+      end
+    end
+  end
+end

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

@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+# Copyright 2020 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Excon
+      module Middlewares
+        # Excon middleware for instrumentation
+        class TracerMiddleware < ::Excon::Middleware::Base
+          HTTP_METHODS_SYMBOL_TO_STRING = {
+            connect: 'CONNECT',
+            delete: 'DELETE',
+            get: 'GET',
+            head: 'HEAD',
+            options: 'OPTIONS',
+            patch: 'PATCH',
+            post: 'POST',
+            put: 'PUT',
+            trace: 'TRACE'
+          }.freeze
+
+          def request_call(datum) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+            begin
+              unless datum.key?(:otel_span)
+                http_method = HTTP_METHODS_SYMBOL_TO_STRING[datum[:method]]
+
+                tracer.start_span(
+                  "HTTP #{http_method}",
+                  attributes: {
+                    'component' => 'http',
+                    'http.host' => datum[:host],
+                    'http.method' => http_method,
+                    'http.scheme' => datum[:scheme],
+                    'http.target' => datum[:path]
+                  },
+                  kind: :client
+                ).tap do |span|
+                  datum[:otel_span] = span
+                  tracer.with_span(span) do
+                    OpenTelemetry.propagation.inject(datum[:headers])
+                  end
+                end
+              end
+            rescue StandardError => e
+              OpenTelemetry.logger.debug(e.message)
+            end
+
+            @stack.request_call(datum)
+          end
+
+          def response_call(datum)
+            @stack.response_call(datum).tap do |d|
+              handle_response(d)
+            end
+          end
+
+          def error_call(datum)
+            handle_response(datum)
+            @stack.error_call(datum)
+          end
+
+          # Returns a copy of the default stack with the trace middleware injected
+          def self.around_default_stack
+            ::Excon.defaults[:middlewares].dup.tap do |default_stack|
+              # If the default stack contains a version of the trace middleware already...
+              existing_trace_middleware = default_stack.find { |m| m <= TracerMiddleware }
+              default_stack.delete(existing_trace_middleware) if existing_trace_middleware
+
+              # Inject after the ResponseParser middleware
+              response_middleware_index = default_stack.index(::Excon::Middleware::ResponseParser).to_i
+              default_stack.insert(response_middleware_index + 1, self)
+            end
+          end
+
+          private
+
+          def handle_response(datum) # rubocop:disable Metrics/AbcSize, Metrics/MethodLength
+            if datum.key?(:otel_span)
+              datum[:otel_span].tap do |span|
+                return span if span.end_timestamp
+
+                if datum.key?(:response)
+                  response = datum[:response]
+                  span.set_attribute('http.status_code', response[:status])
+                  span.set_attribute('http.status_text', response[:reason_phrase])
+                  span.status = OpenTelemetry::Trace::Status.http_to_status(
+                    response[:status]
+                  )
+                end
+
+                if datum.key?(:error)
+                  span.status = OpenTelemetry::Trace::Status.new(
+                    OpenTelemetry::Trace::Status::UNKNOWN_ERROR,
+                    description: "Request has failed: #{datum[:error]}"
+                  )
+                end
+
+                span.finish
+                datum.delete(:otel_span)
+              end
+            end
+          rescue StandardError => e
+            OpenTelemetry.logger.debug(e.message)
+          end
+
+          def tracer
+            Excon::Adapter.instance.tracer
+          end
+        end
+      end
+    end
+  end
+end

adapters/excon/lib/opentelemetry/adapters/excon/version.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+# Copyright 2020 OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+module OpenTelemetry
+  module Adapters
+    module Excon
+      VERSION = '0.0.0'
+    end
+  end
+end