feat: MySQL2 semantic convention stability migration

instrumentation/mysql2/Appraisals

@@ -1,5 +1,13 @@
 # frozen_string_literal: true
 
-appraise 'mysql2-0.4.0' do
-  gem 'mysql2'
+# To facilitate database semantic convention stability migration, we are using
+# appraisal to test the different semantic convention modes along with different
+# gem versions. For more information on the semantic convention modes, see:
+# https://opentelemetry.io/docs/specs/semconv/non-normative/db-migration/
+
+semconv_stability = %w[old stable dup]
+semconv_stability.each do |stability|
+  appraise "mysql2-0.4.0-#{stability}" do
+    gem 'mysql2'
+  end
 end

instrumentation/mysql2/README.md

@@ -75,3 +75,19 @@ The `opentelemetry-instrumentation-mysql2` gem is distributed under the Apache 2
 [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
+
+## Database semantic convention stability
+
+In the OpenTelemetry ecosystem, database semantic conventions have now reached a stable state. However, the initial Mysql2 instrumentation was introduced before this stability was achieved, which resulted in database attributes being based on an older version of the semantic conventions.
+
+To facilitate the migration to stable semantic conventions, you can use the `OTEL_SEMCONV_STABILITY_OPT_IN` environment variable. This variable allows you to opt-in to the new stable conventions, ensuring compatibility and future-proofing your instrumentation.
+
+When setting the value for `OTEL_SEMCONV_STABILITY_OPT_IN`, you can specify which conventions you wish to adopt:
+
+- `database` - Emits the stable database and networking conventions and ceases emitting the old conventions previously emitted by the instrumentation.
+- `database/dup` - Emits both the old and stable database and networking conventions, enabling a phased rollout of the stable semantic conventions.
+- Default behavior (in the absence of either value) is to continue emitting the old database and networking conventions the instrumentation previously emitted.
+
+During the transition from old to stable conventions, Mysql2 instrumentation code comes in three patch versions: `dup`, `old`, and `stable`. These versions are identical except for the attributes they send. Any changes to Mysql2 instrumentation should consider all three patches.
+
+For additional information on migration, please refer to our [documentation](https://opentelemetry.io/docs/specs/semconv/non-normative/db-migration/).

instrumentation/mysql2/lib/opentelemetry/instrumentation/mysql2/instrumentation.rb

@@ -11,8 +11,9 @@ module Mysql2
       # instrumentation
       class Instrumentation < OpenTelemetry::Instrumentation::Base
         install do |_config|
-          require_dependencies
-          patch_client
+          patch_type = determine_semconv
+          send(:"require_dependencies_#{patch_type}")
+          send(:"patch_client_#{patch_type}")
         end
 
         present do
@@ -26,12 +27,41 @@ class Instrumentation < OpenTelemetry::Instrumentation::Base
 
         private
 
-        def require_dependencies
-          require_relative 'patches/client'
+        def determine_semconv
+          stability_opt_in = ENV.fetch('OTEL_SEMCONV_STABILITY_OPT_IN', '')
+          values = stability_opt_in.split(',').map(&:strip)
+
+          if values.include?('database/dup')
+            'dup'
+          elsif values.include?('database')
+            'stable'
+          else
+            'old'
+          end
+        end
+
+        def require_dependencies_dup
+          require_relative 'patches/dup/client'
+        end
+
+        def require_dependencies_old
+          require_relative 'patches/old/client'
+        end
+
+        def require_dependencies_stable
+          require_relative 'patches/stable/client'
+        end
+
+        def patch_client_dup
+          ::Mysql2::Client.prepend(Patches::Dup::Client)
+        end
+
+        def patch_client_old
+          ::Mysql2::Client.prepend(Patches::Old::Client)
         end
 
-        def patch_client
-          ::Mysql2::Client.prepend(Patches::Client)
+        def patch_client_stable
+          ::Mysql2::Client.prepend(Patches::Stable::Client)
         end
       end
     end

instrumentation/mysql2/lib/opentelemetry/instrumentation/mysql2/patches/dup/client.rb

@@ -0,0 +1,111 @@
+# frozen_string_literal: true
+
+# Copyright The OpenTelemetry Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+require 'opentelemetry-helpers-mysql'
+require 'opentelemetry-helpers-sql-obfuscation'
+
+module OpenTelemetry
+  module Instrumentation
+    module Mysql2
+      module Patches
+        module Dup
+          # Module to prepend to Mysql2::Client for instrumentation
+          module Client
+            def query(sql, options = {})
+              tracer.in_span(
+                _otel_span_name(sql),
+                attributes: _otel_span_attributes(sql),
+                kind: :client
+              ) do
+                super
+              end
+            end
+
+            def prepare(sql)
+              tracer.in_span(
+                _otel_span_name(sql),
+                attributes: _otel_span_attributes(sql),
+                kind: :client
+              ) do
+                super
+              end
+            end
+
+            private
+
+            def _otel_span_name(sql)
+              OpenTelemetry::Helpers::MySQL.database_span_name(
+                sql,
+                OpenTelemetry::Instrumentation::Mysql2.attributes[
+                  'db.operation.name'
+                ],
+                _otel_database_name,
+                config
+              )
+            end
+
+            def _otel_span_attributes(sql)
+              attributes = _otel_client_attributes
+              case config[:db_statement]
+              when :include
+                attributes[SemanticConventions::Trace::DB_STATEMENT] = sql
+                attributes['db.query.text'] = sql
+              when :obfuscate
+                attributes[SemanticConventions::Trace::DB_STATEMENT] =
+                  OpenTelemetry::Helpers::SqlObfuscation.obfuscate_sql(
+                    sql, obfuscation_limit: config[:obfuscation_limit], adapter: :mysql
+                  )
+                attributes['db.query.text'] =
+                  OpenTelemetry::Helpers::SqlObfuscation.obfuscate_sql(
+                    sql, obfuscation_limit: config[:obfuscation_limit], adapter: :mysql
+                  )
+              end
+
+              attributes.merge!(OpenTelemetry::Instrumentation::Mysql2.attributes)
+              attributes.compact!
+              attributes
+            end
+
+            def _otel_database_name
+              # https://github.com/brianmario/mysql2/blob/ca08712c6c8ea672df658bb25b931fea22555f27/lib/mysql2/client.rb#L78
+              (query_options[:database] || query_options[:dbname] || query_options[:db])&.to_s
+            end
+
+            def _otel_client_attributes
+              # The client specific attributes can be found via the query_options instance variable
+              # exposed on the mysql2 Client
+              # https://github.com/brianmario/mysql2/blob/ca08712c6c8ea672df658bb25b931fea22555f27/lib/mysql2/client.rb#L25-L26
+              host = (query_options[:host] || query_options[:hostname]).to_s
+              port = query_options[:port].to_s
+
+              attributes = {
+                SemanticConventions::Trace::DB_SYSTEM => 'mysql',
+                SemanticConventions::Trace::NET_PEER_NAME => host,
+                SemanticConventions::Trace::NET_PEER_PORT => port,
+                'db.system.name' => 'mysql',
+                'server.address' => host,
+                'server.port' => port
+              }
+
+              attributes[SemanticConventions::Trace::DB_NAME] = _otel_database_name
+              attributes['db.namespace'] = _otel_database_name
+              attributes[SemanticConventions::Trace::PEER_SERVICE] = config[:peer_service]
+              attributes
+            end
+
+            def tracer
+              Mysql2::Instrumentation.instance.tracer
+            end
+
+            def config
+              Mysql2::Instrumentation.instance.config
+            end
+          end
+        end
+      end
+    end
+  end
+end