Implement Mysql2 integration configuration (#559)

* Refactored: Mysql2 to use Datadog::Contrib::Integration.

* Fixed: Mysql2 tests not working locally.

docker-compose.yml

@@ -217,6 +217,7 @@ services:
   mysql:
     image: mysql:5.6
     environment:
+      - MYSQL_DATABASE=$TEST_MYSQL_DB
       - MYSQL_ROOT_PASSWORD=$TEST_MYSQL_ROOT_PASSWORD
       - MYSQL_PASSWORD=$TEST_MYSQL_PASSWORD
       - MYSQL_USER=$TEST_MYSQL_USER

lib/ddtrace.rb

@@ -59,7 +59,7 @@ def configure(target = configuration, opts = {})
 require 'ddtrace/contrib/http/integration'
 require 'ddtrace/contrib/integration'
 require 'ddtrace/contrib/mongodb/patcher'
-require 'ddtrace/contrib/mysql2/patcher'
+require 'ddtrace/contrib/mysql2/integration'
 require 'ddtrace/contrib/racecar/integration'
 require 'ddtrace/contrib/rack/integration'
 require 'ddtrace/contrib/rails/integration'

lib/ddtrace/contrib/mysql2/client.rb

@@ -1,5 +1,7 @@
-require 'ddtrace/ext/sql'
 require 'ddtrace/ext/app_types'
+require 'ddtrace/ext/net'
+require 'ddtrace/ext/sql'
+require 'ddtrace/contrib/mysql2/ext'
 
 module Datadog
   module Contrib
@@ -34,21 +36,21 @@ module InstanceMethods
           end
 
           def query(sql, options = {})
-            datadog_pin.tracer.trace('mysql2.query') do |span|
+            datadog_pin.tracer.trace(Ext::SPAN_QUERY) do |span|
               span.resource = sql
               span.service = datadog_pin.service
               span.span_type = Datadog::Ext::SQL::TYPE
-              span.set_tag('mysql2.db.name', query_options[:database])
-              span.set_tag('out.host', query_options[:host])
-              span.set_tag('out.port', query_options[:port])
+              span.set_tag(Ext::TAG_DB_NAME, query_options[:database])
+              span.set_tag(Datadog::Ext::NET::TARGET_HOST, query_options[:host])
+              span.set_tag(Datadog::Ext::NET::TARGET_PORT, query_options[:port])
               super(sql, options)
             end
           end
 
           def datadog_pin
             @datadog_pin ||= Datadog::Pin.new(
               Datadog.configuration[:mysql2][:service_name],
-              app: 'mysql2',
+              app: Ext::APP,
               app_type: Datadog::Ext::AppTypes::DB,
               tracer: Datadog.configuration[:mysql2][:tracer]
             )

lib/ddtrace/contrib/mysql2/configuration/settings.rb

@@ -0,0 +1,16 @@
+require 'ddtrace/contrib/configuration/settings'
+require 'ddtrace/contrib/mysql2/ext'
+
+module Datadog
+  module Contrib
+    module Mysql2
+      module Configuration
+        # Custom settings for the Mysql2 integration
+        class Settings < Contrib::Configuration::Settings
+          option :service_name, default: Ext::SERVICE_NAME
+          option :tracer, default: Datadog.tracer
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/mysql2/ext.rb

@@ -0,0 +1,15 @@
+module Datadog
+  module Contrib
+    module Mysql2
+      # Mysql2 integration constants
+      module Ext
+        APP = 'mysql2'.freeze
+        SERVICE_NAME = 'mysql2'.freeze
+
+        SPAN_QUERY = 'mysql2.query'.freeze
+
+        TAG_DB_NAME = 'mysql2.db.name'.freeze
+      end
+    end
+  end
+end

lib/ddtrace/contrib/mysql2/integration.rb

@@ -0,0 +1,32 @@
+require 'ddtrace/contrib/integration'
+require 'ddtrace/contrib/mysql2/configuration/settings'
+require 'ddtrace/contrib/mysql2/patcher'
+
+module Datadog
+  module Contrib
+    module Mysql2
+      # Description of Mysql2 integration
+      class Integration
+        include Contrib::Integration
+
+        register_as :mysql2
+
+        def self.version
+          Gem.loaded_specs['mysql2'] && Gem.loaded_specs['mysql2'].version
+        end
+
+        def self.present?
+          super && defined?(::Mysql2)
+        end
+
+        def default_configuration
+          Configuration::Settings.new
+        end
+
+        def patcher
+          Patcher
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/mysql2/patcher.rb

@@ -1,37 +1,27 @@
+require 'ddtrace/contrib/patcher'
 require 'ddtrace/contrib/mysql2/client'
 
 module Datadog
   module Contrib
     module Mysql2
-      # Mysql2 patcher
+      # Patcher enables patching of 'mysql2' module.
       module Patcher
-        include Base
-
-        register_as :mysql2
-        option :service_name, default: 'mysql2'
-        option :tracer, default: Datadog.tracer
-
-        @patched = false
+        include Contrib::Patcher
 
         module_function
 
-        def patch
-          return @patched if patched? || !compatible?
-
-          patch_mysql2_client
-
-          @patched = true
-        rescue StandardError => e
-          Tracer.log.error("Unable to apply mysql2 integration: #{e}")
-          @patched
-        end
-
         def patched?
-          @patched
+          done?(:mysql2)
         end
 
-        def compatible?
-          defined?(::Mysql2)
+        def patch
+          do_once(:mysql2) do
+            begin
+              patch_mysql2_client
+            rescue StandardError => e
+              Datadog::Tracer.log.error("Unable to apply mysql2 integration: #{e}")
+            end
+          end
         end
 
         def patch_mysql2_client

spec/ddtrace/contrib/mysql2/patcher_spec.rb

@@ -19,7 +19,7 @@
   let(:host) { ENV.fetch('TEST_MYSQL_HOST') { '127.0.0.1' } }
   let(:port) { ENV.fetch('TEST_MYSQL_PORT') { '3306' } }
   let(:database) { ENV.fetch('TEST_MYSQL_DB') { 'mysql' } }
-  let(:username) { ENV.fetch('TEST_MYSQL_USERNAME') { 'root' } }
+  let(:username) { ENV.fetch('TEST_MYSQL_USER') { 'root' } }
   let(:password) { ENV.fetch('TEST_MYSQL_PASSWORD') { 'root' } }
 
   let(:pin) { client.datadog_pin }