Add prometheus trace

lib/graphql/tracing.rb

@@ -19,7 +19,7 @@
 require "graphql/tracing/new_relic_trace"
 require "graphql/tracing/scout_trace"
 require "graphql/tracing/statsd_trace"
-# require "graphql/tracing/prometheus_trace"
+require "graphql/tracing/prometheus_trace"
 if defined?(PrometheusExporter::Server)
   require "graphql/tracing/prometheus_tracing/graphql_collector"
 end

lib/graphql/tracing/prometheus_trace.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+module GraphQL
+  module Tracing
+    module PrometheusTrace
+      include PlatformTrace
+
+      def initialize(client: PrometheusExporter::Client.default, keys_whitelist: ["execute_field", "execute_field_lazy"], collector_type: "graphql", **rest)
+        @client = client
+        @keys_whitelist = keys_whitelist
+        @collector_type = collector_type
+
+        super(**rest)
+      end
+
+      {
+        'lex' => "graphql.lex",
+        'parse' => "graphql.parse",
+        'validate' => "graphql.validate",
+        'analyze_query' => "graphql.analyze",
+        'analyze_multiplex' => "graphql.analyze",
+        'execute_multiplex' => "graphql.execute",
+        'execute_query' => "graphql.execute",
+        'execute_query_lazy' => "graphql.execute",
+      }.each do |trace_method, platform_key|
+        module_eval <<-RUBY, __FILE__, __LINE__
+          def #{trace_method}(**data, &block)
+            instrument_execution("#{platform_key}", "#{trace_method}", &block)
+          end
+        RUBY
+      end
+
+      def platform_execute_field(platform_key, _data, &block)
+        instrument_execution(platform_key, "execute_field", &block)
+      end
+
+      def platform_execute_field_lazy(platform_key, _data, &block)
+        instrument_execution(platform_key, "execute_field_lazy", &block)
+      end
+
+      def platform_authorized(platform_key, &block)
+        instrument_execution(platform_key, "authorized", &block)
+      end
+
+      def platform_authorized_lazy(platform_key, &block)
+        instrument_execution(platform_key, "authorized_lazy", &block)
+      end
+
+      def platform_resolve_type(platform_key, &block)
+        instrument_execution(platform_key, "resolve_type", &block)
+      end
+
+      def platform_resolve_type_lazy(platform_key, &block)
+        instrument_execution(platform_key, "resolve_type_lazy", &block)
+      end
+
+      def platform_field_key(type, field)
+        "#{type.graphql_name}.#{field.graphql_name}"
+      end
+
+      def platform_authorized_key(type)
+        "#{type.graphql_name}.authorized"
+      end
+
+      def platform_resolve_type_key(type)
+        "#{type.graphql_name}.resolve_type"
+      end
+
+      private
+
+      def instrument_execution(platform_key, key, &block)
+        if @keys_whitelist.include?(key)
+          start = ::Process.clock_gettime ::Process::CLOCK_MONOTONIC
+          result = block.call
+          duration = ::Process.clock_gettime(::Process::CLOCK_MONOTONIC) - start
+          @client.send_json(
+            type: @collector_type,
+            duration: duration,
+            platform_key: platform_key,
+            key: key
+          )
+          result
+        else
+          yield
+        end
+      end
+    end
+  end
+end

spec/graphql/tracing/prometheus_trace_spec.rb

@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+describe GraphQL::Tracing::PrometheusTracing do
+  module PrometheusTraceTest
+    class Query < GraphQL::Schema::Object
+      field :int, Integer, null: false
+
+      def int
+        1
+      end
+    end
+
+    class Schema < GraphQL::Schema
+      query Query
+
+    end
+  end
+
+  describe "Observing" do
+    it "sends JSON to Prometheus client" do
+      client = Minitest::Mock.new
+
+      client.expect :send_json, true do |obj|
+        obj[:type] == 'graphql' &&
+          obj[:key] == 'execute_field' &&
+          obj[:platform_key] == 'Query.int'
+      end
+
+      PrometheusTraceTest::Schema.trace_with GraphQL::Tracing::PrometheusTrace,
+        client: client,
+        trace_scalars: true
+
+        PrometheusTraceTest::Schema.execute "query X { int }"
+    end
+  end
+end