feat: instrument mysql2 prepare statement (#862)

* feat: instrument prepare for mysql2 lib

* revision

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

@@ -14,7 +14,40 @@ module Patches
         # Module to prepend to Mysql2::Client for instrumentation
         module Client
           def query(sql, options = {})
-            attributes = client_attributes
+            tracer.in_span(
+              _otel_span_name(sql),
+              attributes: _otel_span_attributes(sql),
+              kind: :client
+            ) do
+              super(sql, options)
+            end
+          end
+
+          def prepare(sql)
+            tracer.in_span(
+              _otel_span_name(sql),
+              attributes: _otel_span_attributes(sql),
+              kind: :client
+            ) do
+              super(sql)
+            end
+          end
+
+          private
+
+          def _otel_span_name(sql)
+            OpenTelemetry::Helpers::MySQL.database_span_name(
+              sql,
+              OpenTelemetry::Instrumentation::Mysql2.attributes[
+                SemanticConventions::Trace::DB_OPERATION
+              ],
+              _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
@@ -24,30 +57,18 @@ def query(sql, options = {})
                   sql, obfuscation_limit: config[:obfuscation_limit], adapter: :mysql
                 )
             end
-            tracer.in_span(
-              OpenTelemetry::Helpers::MySQL.database_span_name(
-                sql,
-                OpenTelemetry::Instrumentation::Mysql2.attributes[
-                  SemanticConventions::Trace::DB_OPERATION
-                ],
-                database_name,
-                config
-              ),
-              attributes: attributes.merge!(OpenTelemetry::Instrumentation::Mysql2.attributes),
-              kind: :client
-            ) do
-              super(sql, options)
-            end
-          end
 
-          private
+            attributes.merge!(OpenTelemetry::Instrumentation::Mysql2.attributes)
+            attributes.compact!
+            attributes
+          end
 
-          def database_name
+          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 client_attributes
+          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
@@ -59,8 +80,9 @@ def client_attributes
               SemanticConventions::Trace::NET_PEER_NAME => host,
               SemanticConventions::Trace::NET_PEER_PORT => port
             }
-            attributes[SemanticConventions::Trace::DB_NAME] = database_name if database_name
-            attributes[SemanticConventions::Trace::PEER_SERVICE] = config[:peer_service] if config[:peer_service]
+
+            attributes[SemanticConventions::Trace::DB_NAME] = _otel_database_name
+            attributes[SemanticConventions::Trace::PEER_SERVICE] = config[:peer_service]
             attributes
           end
 

instrumentation/mysql2/test/opentelemetry/instrumentation/mysql2/instrumentation_test.rb

@@ -88,6 +88,53 @@
       end
     end
 
+    describe 'prepare statement' do
+      it 'after requests with prepare' do
+        client.prepare('SELECT 1')
+
+        _(span.name).must_equal 'select'
+        _(span.attributes['db.system']).must_equal 'mysql'
+        _(span.attributes['db.name']).must_equal 'mysql'
+        _(span.attributes['db.statement']).must_equal 'SELECT 1'
+        _(span.attributes['net.peer.name']).must_equal host.to_s
+        _(span.attributes['net.peer.port']).must_equal port.to_s
+      end
+
+      it 'after requests with prepare select ?' do
+        client.prepare('SELECT ?')
+
+        _(span.name).must_equal 'select'
+        _(span.attributes['db.system']).must_equal 'mysql'
+        _(span.attributes['db.name']).must_equal 'mysql'
+        _(span.attributes['db.statement']).must_equal 'SELECT ?'
+        _(span.attributes['net.peer.name']).must_equal host.to_s
+        _(span.attributes['net.peer.port']).must_equal port.to_s
+      end
+
+      it 'query ? sequences for db.statement with prepare' do
+        sql = 'SELECT * from users where users.id = ? and users.email = ?'
+        expect do
+          client.prepare(sql)
+        end.must_raise Mysql2::Error
+
+        _(span.attributes['db.system']).must_equal 'mysql'
+        _(span.attributes['db.name']).must_equal 'mysql'
+        _(span.name).must_equal 'select'
+        _(span.attributes['db.statement']).must_equal sql
+        _(span.attributes['net.peer.name']).must_equal host.to_s
+        _(span.attributes['net.peer.port']).must_equal port.to_s
+      end
+
+      it 'query invalid byte sequences for db.statement without prepare' do
+        sql = 'SELECT * from users where users.id = ? and users.email = ?'
+        expect do
+          client.query(sql)
+        end.must_raise Mysql2::Error
+
+        _(span.events[0].attributes['exception.message'].slice(0, 37)).must_equal 'You have an error in your SQL syntax;'
+      end
+    end
+
     it 'after requests' do
       client.query('SELECT 1')