Add opentracing integration for graphql

Extends existing graphql's tracer with opentracing measurements. Because
it also adds Tracing::Graphql class (for opentracing), it also renames
Graphql::Tracing class to Graphql::GenericTracing to minimize confusion
with similar class names.

1 files changed, 19 insertions, 3 deletions

diff --git a/lib/gitlab/graphql/tracing.rb b/lib/gitlab/graphql/generic_tracing.rb
index 6b505e4262b..936b22d5afa 100644
--- a/lib/gitlab/graphql/tracing.rb
+++ b/lib/gitlab/graphql/generic_tracing.rb
@@ -1,8 +1,11 @@
 # frozen_string_literal: true
 
+# This class is used as a hook to observe graphql runtime events. From this
+# hook both gitlab metrics and opentracking measurements are generated
+
 module Gitlab
   module Graphql
-    class Tracing < GraphQL::Tracing::PlatformTracing
+    class GenericTracing < GraphQL::Tracing::PlatformTracing
       self.platform_keys = {
         'lex' => 'graphql.lex',
         'parse' => 'graphql.parse',
@@ -21,17 +24,30 @@ module Gitlab
       end
 
       def platform_trace(platform_key, key, data, &block)
+        tags = { platform_key: platform_key, key: key }
         start = Gitlab::Metrics::System.monotonic_time
 
-        yield
+        with_labkit_tracing(tags, &block)
       ensure
         duration = Gitlab::Metrics::System.monotonic_time - start
 
-        graphql_duration_seconds.observe({ platform_key: platform_key, key: key }, duration)
+        graphql_duration_seconds.observe(tags, duration)
       end
 
       private
 
+      def with_labkit_tracing(tags, &block)
+        return yield unless Labkit::Tracing.enabled?
+
+        name = "#{tags[:platform_key]}.#{tags[:key]}"
+        span_tags = {
+          'component' => 'web',
+          'span.kind' => 'server'
+        }.merge(tags.stringify_keys)
+
+        Labkit::Tracing.with_tracing(operation_name: name, tags: span_tags, &block)
+      end
+
       def graphql_duration_seconds
         @graphql_duration_seconds ||= Gitlab::Metrics.histogram(
           :graphql_duration_seconds,