Don't depend on `Rails` for Redis configuration file pathsrs-redis-config-paths

The `Rails` object was not always available in all tasks that require
Redis access, such as `mail_room`, so the constant pointing to the
configuration path was never defined, but we still attempted to access
it in `config_file_name`, resulting in a `NameError` exception.

Further, there was no benefit to defining these paths in a constant to
begin with -- they're only accessed in one place, and it was within the
class where they were being defined. We can just provide them at
run-time instead.

Further _still_, we were calling `File.expand_path` on the absolute path
returned by `Rails.root.join`, which was rather pointless.

5 files changed, 19 insertions, 16 deletions

diff --git a/lib/gitlab/redis/cache.rb b/lib/gitlab/redis/cache.rb
index b0da516ff83..9bf019b72e6 100644
--- a/lib/gitlab/redis/cache.rb
+++ b/lib/gitlab/redis/cache.rb
@@ -7,9 +7,6 @@ module Gitlab
       CACHE_NAMESPACE = 'cache:gitlab'.freeze
       DEFAULT_REDIS_CACHE_URL = 'redis://localhost:6380'.freeze
       REDIS_CACHE_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_CACHE_CONFIG_FILE'.freeze
-      if defined?(::Rails) && ::Rails.root.present?
-        DEFAULT_REDIS_CACHE_CONFIG_FILE_NAME = ::Rails.root.join('config', 'redis.cache.yml').freeze
-      end
 
       class << self
         def default_url
@@ -22,7 +19,7 @@ module Gitlab
           return file_name unless file_name.nil?
 
           # otherwise, if config files exists for this class, use it
-          file_name = File.expand_path(DEFAULT_REDIS_CACHE_CONFIG_FILE_NAME, __dir__)
+          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
diff --git a/lib/gitlab/redis/queues.rb b/lib/gitlab/redis/queues.rb
index f9249d05565..e1695aafbeb 100644
--- a/lib/gitlab/redis/queues.rb
+++ b/lib/gitlab/redis/queues.rb
@@ -8,9 +8,6 @@ module Gitlab
       MAILROOM_NAMESPACE = 'mail_room:gitlab'.freeze
       DEFAULT_REDIS_QUEUES_URL = 'redis://localhost:6381'.freeze
       REDIS_QUEUES_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_QUEUES_CONFIG_FILE'.freeze
-      if defined?(::Rails) && ::Rails.root.present?
-        DEFAULT_REDIS_QUEUES_CONFIG_FILE_NAME = ::Rails.root.join('config', 'redis.queues.yml').freeze
-      end
 
       class << self
         def default_url
@@ -23,7 +20,7 @@ module Gitlab
           return file_name if file_name
 
           # otherwise, if config files exists for this class, use it
-          file_name = File.expand_path(DEFAULT_REDIS_QUEUES_CONFIG_FILE_NAME, __dir__)
+          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
diff --git a/lib/gitlab/redis/shared_state.rb b/lib/gitlab/redis/shared_state.rb
index 395dcf082da..10bec7a90da 100644
--- a/lib/gitlab/redis/shared_state.rb
+++ b/lib/gitlab/redis/shared_state.rb
@@ -7,9 +7,6 @@ module Gitlab
       SESSION_NAMESPACE = 'session:gitlab'.freeze
       DEFAULT_REDIS_SHARED_STATE_URL = 'redis://localhost:6382'.freeze
       REDIS_SHARED_STATE_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_SHARED_STATE_CONFIG_FILE'.freeze
-      if defined?(::Rails) && ::Rails.root.present?
-        DEFAULT_REDIS_SHARED_STATE_CONFIG_FILE_NAME = ::Rails.root.join('config', 'redis.shared_state.yml').freeze
-      end
 
       class << self
         def default_url
@@ -22,7 +19,7 @@ module Gitlab
           return file_name if file_name
 
           # otherwise, if config files exists for this class, use it
-          file_name = File.expand_path(DEFAULT_REDIS_SHARED_STATE_CONFIG_FILE_NAME, __dir__)
+          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
diff --git a/lib/gitlab/redis/wrapper.rb b/lib/gitlab/redis/wrapper.rb
index c43b37dde74..8ad06480575 100644
--- a/lib/gitlab/redis/wrapper.rb
+++ b/lib/gitlab/redis/wrapper.rb
@@ -8,9 +8,6 @@ module Gitlab
     class Wrapper
       DEFAULT_REDIS_URL = 'redis://localhost:6379'.freeze
       REDIS_CONFIG_ENV_VAR_NAME = 'GITLAB_REDIS_CONFIG_FILE'.freeze
-      if defined?(::Rails) && ::Rails.root.present?
-        DEFAULT_REDIS_CONFIG_FILE_NAME = ::Rails.root.join('config', 'resque.yml').freeze
-      end
 
       class << self
         delegate :params, :url, to: :new
@@ -49,13 +46,21 @@ module Gitlab
           DEFAULT_REDIS_URL
         end
 
+        # Return the absolute path to a Rails configuration file
+        #
+        # We use this instead of `Rails.root` because for certain tasks
+        # utilizing these classes, `Rails` might not be available.
+        def config_file_path(filename)
+          File.expand_path("../../../config/#{filename}", __dir__)
+        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 = File.expand_path(DEFAULT_REDIS_CONFIG_FILE_NAME, __dir__)
+          file_name = config_file_path('resque.yml')
           return file_name if File.file?(file_name)
 
           # nil will force use of DEFAULT_REDIS_URL when config file is absent
diff --git a/spec/lib/gitlab/redis/wrapper_spec.rb b/spec/lib/gitlab/redis/wrapper_spec.rb
index e1becd0a614..0c22a0d62cc 100644
--- a/spec/lib/gitlab/redis/wrapper_spec.rb
+++ b/spec/lib/gitlab/redis/wrapper_spec.rb
@@ -17,4 +17,11 @@ describe Gitlab::Redis::Wrapper do
   let(:class_redis_url) { Gitlab::Redis::Wrapper::DEFAULT_REDIS_URL }
 
   include_examples "redis_shared_examples"
+
+  describe '.config_file_path' do
+    it 'returns the absolute path to the configuration file' do
+      expect(described_class.config_file_path('foo.yml'))
+        .to eq Rails.root.join('config', 'foo.yml').to_s
+    end
+  end
 end