New Relic GraphQL Ruby instrumentation

foo_type.rb

Types::FoosType = GraphQL::ObjectType.define do
  field :foos, !types[Types::FooType] do
    timed true # enable New Relic trace_execution_scoped
    description "Returns foos"
    argument :per, types.Int, default_value: 20
    argument :page, types.Int, default_value: 1
    # Moving to cursor pagination would be better
    resolve(...)
  end
end

new_relic_instrumentation.rb

class NewRelicInstrumentation
  extend ::NewRelic::Agent::MethodTracer

  def before_query(query)
    query.context[:query_start_time] = Time.current
  end
  
  # Add extra attributes to new Relic
  def after_query(query)
    duration = Time.current - query.context[:query_start_time]
    ::NewRelic::Agent.add_custom_attributes(
      {
        GQLDuration: duration * 1000.0,
        GQLOperationName: query.operation_name
      }
    )

    if query.context[:graphql_controller]
      NewRelic::Agent.set_transaction_name("GraphQL/#{query.operation_name}")
    end
  end

  def instrument(type, field)
    if field.metadata[:timed]
      old_resolve_proc = field.resolve_proc
      new_resolve_proc = lambda do |obj, args, ctx|
        self.class.trace_execution_scoped(["GraphQL/field/#{type.name}.#{field.name}"]) do
          old_resolve_proc.call(obj, args, ctx)
        end
      end

      field.redefine do
        resolve(new_resolve_proc)
      end
    else
      field
    end
  end
end

schema.rb

# allow fields to used timed true
GraphQL::Field.accepts_definitions timed: GraphQL::Define.assign_metadata_key(:timed)

GraphQLSchema = GraphQL::Schema.define do
  query(QueryRootType)
  mutation(MutationRootType)

  instrument(:query, NewRelicInstrumentation.new)
  instrument(:field, NewRelicInstrumentation.new)
end

# Log query depth
log_query_depth = GraphQL::Analysis::QueryDepth.new do |_query, depth|
  ::NewRelic::Agent.add_custom_attributes({ GQLDepth: depth })
  Rails.logger.debug { "[GraphQL Query Depth] #{depth}" }
end
GraphQLSchema.query_analyzers << log_query_depth

# Log query Complexity
log_query_complexity = GraphQL::Analysis::QueryComplexity.new do |_query, complexity|
  ::NewRelic::Agent.add_custom_attributes({ GQLComplexity: complexity })
  Rails.logger.debug { "[GraphQL Query Complexity] #{complexity}" }
end
GraphQLSchema.query_analyzers << log_query_complexity