ViewComponent instrumentation

CHANGELOG.md

@@ -2,7 +2,12 @@
 
 ## v9.7.0
 
-Version 9.7.0 changes the endpoint used to access the cluster name for Elasticsearch instrumentation, adds support for Falcon, and removes the creation of the Ruby/Thread and Ruby/Fiber spans.
+
+Version 9.7.0 introduces ViewComponent instrumentation, changes the endpoint used to access the cluster name for Elasticsearch instrumentation, removes the creation of the Ruby/Thread and Ruby/Fiber spans, and adds support for Falcon.
+
+- **Feature: ViewComponent instrumentation**
+
+  [ViewComponent](https://viewcomponent.org/) is a now an instrumented framework. The agent currently supports Roda versions 2.0.0+. [PR#2367](https://github.com/newrelic/newrelic-ruby-agent/pull/2367) 
 
 - **Feature: Use root path to access Elasticsearch cluster name**
 

lib/new_relic/agent/configuration/default_source.rb

@@ -313,6 +313,7 @@ def self.enforce_fallback(allowed_values: nil, fallback: nil)
         'webpacker:compile'
       ].join(',').freeze
 
+      # rubocop:disable Metrics/CollectionLiteralLength
       DEFAULTS = {
         # Critical
         :agent_enabled => {
@@ -1657,6 +1658,14 @@ def self.enforce_fallback(allowed_values: nil, fallback: nil)
           :allowed_from_server => false,
           :description => 'Controls auto-instrumentation of Stripe at startup. May be one of: `enabled`, `disabled`.'
         },
+        :'instrumentation.view_component' => {
+          :default => 'auto',
+          :public => true,
+          :type => String,
+          :dynamic_name => true,
+          :allowed_from_server => false,
+          :description => 'Controls auto-instrumentation of ViewComponent at startup. May be one of: `auto`, `prepend`, `chain`, `disabled`.'
+        },
         :'stripe.user_data.include' => {
           default: NewRelic::EMPTY_ARRAY,
           public: true,
@@ -2405,6 +2414,7 @@ def self.enforce_fallback(allowed_values: nil, fallback: nil)
           :description => 'This value represents the total amount of memory available to the host (not the process), in mebibytes (1024 squared or 1,048,576 bytes).'
         }
       }.freeze
+      # rubocop:enable Metrics/CollectionLiteralLength
     end
   end
 end

lib/new_relic/agent/instrumentation/view_component.rb

@@ -0,0 +1,26 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+require_relative 'view_component/instrumentation'
+require_relative 'view_component/chain'
+require_relative 'view_component/prepend'
+
+DependencyDetection.defer do
+  named :view_component
+
+  depends_on do
+    defined?(ViewComponent) &&
+      ViewComponent::Base.method_defined?(:render_in)
+  end
+
+  executes do
+    NewRelic::Agent.logger.info('Installing ViewComponent instrumentation')
+
+    if use_prepend?
+      prepend_instrument ViewComponent::Base, NewRelic::Agent::Instrumentation::ViewComponent::Prepend
+    else
+      chain_instrument NewRelic::Agent::Instrumentation::ViewComponent::Chain
+    end
+  end
+end

lib/new_relic/agent/instrumentation/view_component/chain.rb

@@ -0,0 +1,21 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+module NewRelic::Agent::Instrumentation
+  module ViewComponent::Chain
+    def self.instrument!
+      ::ViewComponent::Base.class_eval do
+        include NewRelic::Agent::Instrumentation::ViewComponent
+
+        alias_method(:render_in_without_tracing, :render_in)
+
+        def render_in(*args)
+          render_in_with_tracing(*args) do
+            render_in_without_tracing(*args)
+          end
+        end
+      end
+    end
+  end
+end

lib/new_relic/agent/instrumentation/view_component/instrumentation.rb

@@ -0,0 +1,38 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+module NewRelic::Agent::Instrumentation
+  module ViewComponent
+    INSTRUMENTATION_NAME = NewRelic::Agent.base_name(name)
+
+    def render_in_with_tracing(*args)
+      NewRelic::Agent.record_instrumentation_invocation(INSTRUMENTATION_NAME)
+
+      begin
+        segment = NewRelic::Agent::Tracer.start_segment(
+          name: metric_name(self.class.identifier, self.class.name)
+        )
+        yield
+      rescue => e
+        ::NewRelic::Agent.logger.debug('Error capturing ViewComponent segment', e)
+      ensure
+        segment&.finish
+      end
+    end
+
+    def metric_name(identifier, component)
+      "View/#{metric_path(identifier)}/#{component}"
+    end
+
+    def metric_path(identifier)
+      return 'component' unless identifier
+
+      if (parts = identifier.split('/')).size > 1
+        parts[-2..-1].join('/') # Get filepath by assuming the Rails' structure: app/components/home/example_component.rb
+      else
+        NewRelic::Agent::UNKNOWN_METRIC
+      end
+    end
+  end
+end

lib/new_relic/agent/instrumentation/view_component/prepend.rb

@@ -0,0 +1,13 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+module NewRelic::Agent::Instrumentation
+  module ViewComponent::Prepend
+    include NewRelic::Agent::Instrumentation::ViewComponent
+
+    def render_in(*args)
+      render_in_with_tracing(*args) { super }
+    end
+  end
+end

test/multiverse/suites/rails/rails3_app/my_app.rb

@@ -94,6 +94,8 @@ class MyApp < Rails::Application
 
     post '/parameter_capture', :to => 'parameter_capture#create'
 
+    get '/view_components', :to => 'view_component#index' # This app and route is used in ViewComponent tests
+
     get '/:controller(/:action(/:id))'
   end
 

test/multiverse/suites/view_component/Envfile

@@ -0,0 +1,21 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+instrumentation_methods :chain, :prepend
+
+VIEW_COMPONENT_VERSIONS = [
+  [nil, 2.7],
+  ['2.53.0', 2.4]
+]
+
+def gem_list(view_component_version = nil)
+  <<~RB
+  gem 'rails'
+  gem 'view_component'#{view_component_version}
+  gem 'rack-test'
+  gem 'loofah', '~> 2.20.0' if RUBY_VERSION >= '2.4.0' && RUBY_VERSION < '2.5.0'
+  RB
+end
+
+create_gemfiles(VIEW_COMPONENT_VERSIONS)

test/multiverse/suites/view_component/config/newrelic.yml

@@ -0,0 +1,19 @@
+---
+development:
+  error_collector:
+    enabled: true
+  apdex_t: 0.5
+  monitor_mode: true
+  license_key: bootstrap_newrelic_admin_license_key_000
+  instrumentation:
+    view_component: <%= $instrumentation_method %>
+  app_name: test
+  log_level: debug
+  host: 127.0.0.1
+  api_host: 127.0.0.1
+  transaction_trace:
+    record_sql: obfuscated
+    enabled: true
+    stack_trace_threshold: 0.5
+    transaction_threshold: 1.0
+  capture_params: false

test/multiverse/suites/view_component/view_component_instrumentation_test.rb

@@ -0,0 +1,54 @@
+# This file is distributed under New Relic's license terms.
+# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
+# frozen_string_literal: true
+
+require_relative '../rails/app'
+
+class ExampleComponent < ViewComponent::Base
+  <<~ERB
+    <%= @title %>
+  ERB
+
+  def initialize(title:)
+    @title = title
+  end
+end
+
+class ViewComponentController < ActionController::Base
+  def index
+    render(ExampleComponent.new(title: 'Hello World'))
+  end
+end
+
+class DummyViewComponentInstrumentationClass
+  include NewRelic::Agent::Instrumentation::ViewComponent
+end
+
+class ViewComponentInstrumentationTest < ActionDispatch::IntegrationTest
+  include MultiverseHelpers
+  setup_and_teardown_agent
+
+  FAKE_CLASS = DummyViewComponentInstrumentationClass.new
+
+  def test_metric_recorded
+    get('/view_components')
+
+    assert_metrics_recorded('View/view_component/view_component_instrumentation_test.rb/ExampleComponent')
+  end
+
+  def test_records_nothing_if_tracing_disabled
+    NewRelic::Agent.disable_all_tracing do
+      get('/view_components')
+    end
+
+    assert_metrics_not_recorded('View/view_component/view_component_instrumentation_test.rb/ExampleComponent')
+  end
+
+  def test_metric_path_falsey
+    assert(FAKE_CLASS.metric_path(nil), 'component')
+  end
+
+  def test_metric_path_unknown_file_pattern
+    assert(FAKE_CLASS.metric_path('nothing_to_see_here'), 'unknown')
+  end
+end