Merge branch 'labkit-cache-tracing' into 'master'

Add Redis interceptor tracing

See merge request gitlab-org/gitlab-ce!30238

Gemfile

@@ -283,7 +283,7 @@ gem 'sentry-raven', '~> 2.9'
 gem 'premailer-rails', '~> 1.9.7'
 
 # LabKit: Tracing and Correlation
-gem 'gitlab-labkit', '~> 0.4.2'
+gem 'gitlab-labkit', '~> 0.5'
 
 # I18n
 gem 'ruby_parser', '~> 3.8', require: false

Gemfile.lock

@@ -311,12 +311,13 @@ GEM
     gitaly (1.58.0)
       grpc (~> 1.0)
     github-markup (1.7.0)
-    gitlab-labkit (0.4.2)
+    gitlab-labkit (0.5.2)
       actionpack (~> 5)
       activesupport (~> 5)
       grpc (~> 1.19)
       jaeger-client (~> 0.10)
       opentracing (~> 0.4)
+      redis (> 3.0.0, < 5.0.0)
     gitlab-markup (1.7.0)
     gitlab-sidekiq-fetcher (0.5.1)
       sidekiq (~> 5)
@@ -712,7 +713,7 @@ GEM
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.0.4)
+    rails-html-sanitizer (1.2.0)
       loofah (~> 2.2, >= 2.2.2)
     rails-i18n (5.1.1)
       i18n (>= 0.7, < 2)
@@ -1100,7 +1101,7 @@ DEPENDENCIES
   gettext_i18n_rails_js (~> 1.3)
   gitaly (~> 1.58.0)
   github-markup (~> 1.7.0)
-  gitlab-labkit (~> 0.4.2)
+  gitlab-labkit (~> 0.5)
   gitlab-markup (~> 1.7.0)
   gitlab-sidekiq-fetcher (= 0.5.1)
   gitlab-styles (~> 2.7)

changelogs/unreleased/labkit-cache-tracing.yml

+---
+title: Add Redis interceptor tracing
+merge_request: 30238
+author:
+type: other

config/initializers/tracing.rb

@@ -21,9 +21,13 @@ if Labkit::Tracing.enabled?
     end
   end
 
+  # Instrument Redis
+  Labkit::Tracing::Redis.instrument
+
   # Instrument Rails
   Labkit::Tracing::Rails::ActiveRecordSubscriber.instrument
   Labkit::Tracing::Rails::ActionViewSubscriber.instrument
+  Labkit::Tracing::Rails::ActiveSupportSubscriber.instrument
 
   # In multi-processed clustered architectures (puma, unicorn) don't
   # start tracing until the worker processes are spawned. This works