Factor out redis store duplication

There was a lot of duplicated code between Redis::Cache, Redis::Queues
and Redis::SharedState. This change replaces it with lookups based on
the class name.

lib/gitlab/redis/cache.rb

@@ -7,29 +7,10 @@ module Gitlab
   module Redis
     class Cache < ::Gitlab::Redis::Wrapper
       CACHE_NAMESPACE = 'cache:gitlab'
-      DEFAULT_REDIS_CACHE_URL = 'redis://localhost:6380'
-      REDIS_CACHE_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_CACHE_CONFIG_FILE'
 
       class << self
         def default_url
-          DEFAULT_REDIS_CACHE_URL
-        end
-
-        def config_file_name
-          # if ENV set for this class, use it even if it points to a file does not exist
-          file_name = ENV[REDIS_CACHE_CONFIG_ENV_VAR_NAME]
-          return file_name unless file_name.nil?
-
-          # otherwise, if config files exists for this class, use it
-          file_name = config_file_path('redis.cache.yml')
-          return file_name if File.file?(file_name)
-
-          # this will force use of DEFAULT_REDIS_QUEUES_URL when config file is absent
-          super
-        end
-
-        def instrumentation_class
-          ::Gitlab::Instrumentation::Redis::Cache
+          'redis://localhost:6380'
         end
       end
     end

lib/gitlab/redis/queues.rb

@@ -8,29 +8,10 @@ module Gitlab
     class Queues < ::Gitlab::Redis::Wrapper
       SIDEKIQ_NAMESPACE = 'resque:gitlab'
       MAILROOM_NAMESPACE = 'mail_room:gitlab'
-      DEFAULT_REDIS_QUEUES_URL = 'redis://localhost:6381'
-      REDIS_QUEUES_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_QUEUES_CONFIG_FILE'
 
       class << self
         def default_url
-          DEFAULT_REDIS_QUEUES_URL
-        end
-
-        def config_file_name
-          # if ENV set for this class, use it even if it points to a file does not exist
-          file_name = ENV[REDIS_QUEUES_CONFIG_ENV_VAR_NAME]
-          return file_name if file_name
-
-          # otherwise, if config files exists for this class, use it
-          file_name = config_file_path('redis.queues.yml')
-          return file_name if File.file?(file_name)
-
-          # this will force use of DEFAULT_REDIS_QUEUES_URL when config file is absent
-          super
-        end
-
-        def instrumentation_class
-          ::Gitlab::Instrumentation::Redis::Queues
+          'redis://localhost:6381'
         end
       end
     end

lib/gitlab/redis/shared_state.rb

@@ -10,29 +10,10 @@ module Gitlab
       USER_SESSIONS_NAMESPACE = 'session:user:gitlab'
       USER_SESSIONS_LOOKUP_NAMESPACE = 'session:lookup:user:gitlab'
       IP_SESSIONS_LOOKUP_NAMESPACE = 'session:lookup:ip:gitlab2'
-      DEFAULT_REDIS_SHARED_STATE_URL = 'redis://localhost:6382'
-      REDIS_SHARED_STATE_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_SHARED_STATE_CONFIG_FILE'
 
       class << self
         def default_url
-          DEFAULT_REDIS_SHARED_STATE_URL
-        end
-
-        def config_file_name
-          # if ENV set for this class, use it even if it points to a file does not exist
-          file_name = ENV[REDIS_SHARED_STATE_CONFIG_ENV_VAR_NAME]
-          return file_name if file_name
-
-          # otherwise, if config files exists for this class, use it
-          file_name = config_file_path('redis.shared_state.yml')
-          return file_name if File.file?(file_name)
-
-          # this will force use of DEFAULT_REDIS_SHARED_STATE_URL when config file is absent
-          super
-        end
-
-        def instrumentation_class
-          ::Gitlab::Instrumentation::Redis::SharedState
+          'redis://localhost:6382'
         end
       end
     end

lib/gitlab/redis/wrapper.rb

 # frozen_string_literal: true
 
 # This file should only be used by sub-classes, not directly by any clients of the sub-classes
-# please require all dependencies below:
+
+# Explicitly load parts of ActiveSupport because MailRoom does not load
+# Rails.
 require 'active_support/core_ext/hash/keys'
 require 'active_support/core_ext/module/delegation'
+require 'active_support/core_ext/string/inflections'
 
 module Gitlab
   module Redis
     class Wrapper
-      DEFAULT_REDIS_URL = 'redis://localhost:6379'
-      REDIS_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_CONFIG_FILE'
-
       class << self
         delegate :params, :url, to: :new
 
@@ -52,11 +52,12 @@ module Gitlab
         end
 
         def default_url
-          DEFAULT_REDIS_URL
+          raise NotImplementedError
         end
 
         def config_file_path(filename)
-          File.join(rails_root, 'config', filename)
+          path = File.join(rails_root, 'config', filename)
+          return path if File.file?(path)
         end
 
         # We need this local implementation of Rails.root because MailRoom
@@ -66,20 +67,20 @@ module Gitlab
         end
 
         def config_file_name
-          # if ENV set for wrapper class, use it even if it points to a file does not exist
-          file_name = ENV[REDIS_CONFIG_ENV_VAR_NAME]
-          return file_name unless file_name.nil?
-
-          # otherwise, if config files exists for wrapper class, use it
-          file_name = config_file_path('resque.yml')
-          return file_name if File.file?(file_name)
+          [
+            ENV["GITLAB_REDIS_#{store_name.underscore.upcase}_CONFIG_FILE"],
+            config_file_path("redis.#{store_name.underscore}.yml"),
+            ENV['GITLAB_REDIS_CONFIG_FILE'],
+            config_file_path('resque.yml')
+          ].compact.first
+        end
 
-          # nil will force use of DEFAULT_REDIS_URL when config file is absent
-          nil
+        def store_name
+          name.demodulize
         end
 
         def instrumentation_class
-          raise NotImplementedError
+          "::Gitlab::Instrumentation::Redis::#{store_name}".constantize
         end
       end
 

spec/lib/gitlab/redis/cache_spec.rb

@@ -5,7 +5,7 @@ require 'spec_helper'
 RSpec.describe Gitlab::Redis::Cache do
   let(:instance_specific_config_file) { "config/redis.cache.yml" }
   let(:environment_config_file_name) { "GITLAB_REDIS_CACHE_CONFIG_FILE" }
-  let(:class_redis_url) { Gitlab::Redis::Cache::DEFAULT_REDIS_CACHE_URL }
+  let(:class_redis_url) { 'redis://localhost:6380' }
 
   include_examples "redis_shared_examples"
 end

spec/lib/gitlab/redis/queues_spec.rb

@@ -5,7 +5,7 @@ require 'spec_helper'
 RSpec.describe Gitlab::Redis::Queues do
   let(:instance_specific_config_file) { "config/redis.queues.yml" }
   let(:environment_config_file_name) { "GITLAB_REDIS_QUEUES_CONFIG_FILE" }
-  let(:class_redis_url) { Gitlab::Redis::Queues::DEFAULT_REDIS_QUEUES_URL }
+  let(:class_redis_url) { 'redis://localhost:6381' }
 
   include_examples "redis_shared_examples"
 end

spec/lib/gitlab/redis/shared_state_spec.rb

@@ -5,7 +5,7 @@ require 'spec_helper'
 RSpec.describe Gitlab::Redis::SharedState do
   let(:instance_specific_config_file) { "config/redis.shared_state.yml" }
   let(:environment_config_file_name) { "GITLAB_REDIS_SHARED_STATE_CONFIG_FILE" }
-  let(:class_redis_url) { Gitlab::Redis::SharedState::DEFAULT_REDIS_SHARED_STATE_URL }
+  let(:class_redis_url) { 'redis://localhost:6382' }
 
   include_examples "redis_shared_examples"
 end

spec/lib/gitlab/redis/wrapper_spec.rb

@@ -4,8 +4,14 @@ require 'spec_helper'
 
 RSpec.describe Gitlab::Redis::Wrapper do
   describe '.instrumentation_class' do
-    it 'raises a NotImplementedError' do
-      expect { described_class.instrumentation_class }.to raise_error(NotImplementedError)
+    it 'raises a NameError' do
+      expect { described_class.instrumentation_class }.to raise_error(NameError)
+    end
+  end
+
+  describe '.default_url' do
+    it 'is not implemented' do
+      expect { described_class.default_url }.to raise_error(NotImplementedError)
     end
   end
 end