Merge branch 'brodock/gitlab-ce-feature/redis-sentinel'

# Conflicts:
#	lib/gitlab/redis.rb

16 files changed, 604 insertions, 121 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 58751448d4a..845e68c62af 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -20,6 +20,7 @@ v 8.11.0 (unreleased)
   - Optimize maximum user access level lookup in loading of notes
   - Add "No one can push" as an option for protected branches. !5081
   - Improve performance of AutolinkFilter#text_parse by using XPath
+  - Add experimental Redis Sentinel support !1877
   - Environments have an url to link to
   - Update `timeago` plugin to use multiple string/locale settings
   - Remove unused images (ClemMakesApps)
diff --git a/config/application.rb b/config/application.rb
index 06ebb14a5fe..4a9ed41cbf8 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -107,7 +107,8 @@ module Gitlab
       end
     end
 
-    redis_config_hash = Gitlab::Redis.redis_store_options
+    # Use Redis caching across all environments
+    redis_config_hash = Gitlab::Redis.params
     redis_config_hash[:namespace] = Gitlab::Redis::CACHE_NAMESPACE
     redis_config_hash[:expires_in] = 2.weeks # Cache should not grow forever
     config.cache_store = :redis_store, redis_config_hash
diff --git a/config/initializers/session_store.rb b/config/initializers/session_store.rb
index 0d9d87bac00..70be2617cab 100644
--- a/config/initializers/session_store.rb
+++ b/config/initializers/session_store.rb
@@ -13,9 +13,9 @@ end
 if Rails.env.test?
   Gitlab::Application.config.session_store :cookie_store, key: "_gitlab_session"
 else
-  redis_config = Gitlab::Redis.redis_store_options
+  redis_config = Gitlab::Redis.params
   redis_config[:namespace] = Gitlab::Redis::SESSION_NAMESPACE
-  
+
   Gitlab::Application.config.session_store(
     :redis_store, # Using the cookie_store would enable session replay attacks.
     servers: redis_config,
diff --git a/config/initializers/sidekiq.rb b/config/initializers/sidekiq.rb
index cf49ec2194c..f7e714cd6bc 100644
--- a/config/initializers/sidekiq.rb
+++ b/config/initializers/sidekiq.rb
@@ -1,8 +1,9 @@
+# Custom Redis configuration
+redis_config_hash = Gitlab::Redis.params
+redis_config_hash[:namespace] = Gitlab::Redis::SIDEKIQ_NAMESPACE
+
 Sidekiq.configure_server do |config|
-  config.redis = {
-    url: Gitlab::Redis.url,
-    namespace: Gitlab::Redis::SIDEKIQ_NAMESPACE
-  }
+  config.redis = redis_config_hash
 
   config.server_middleware do |chain|
     chain.add Gitlab::SidekiqMiddleware::ArgumentsLogger if ENV['SIDEKIQ_LOG_ARGUMENTS']
@@ -39,8 +40,5 @@ Sidekiq.configure_server do |config|
 end
 
 Sidekiq.configure_client do |config|
-  config.redis = {
-    url: Gitlab::Redis.url,
-    namespace: Gitlab::Redis::SIDEKIQ_NAMESPACE
-  }
+  config.redis = redis_config_hash
 end
diff --git a/config/mail_room.yml b/config/mail_room.yml
index 7cab24b295e..c639f8260aa 100644
--- a/config/mail_room.yml
+++ b/config/mail_room.yml
@@ -1,47 +1,36 @@
+# If you change this file in a Merge Request, please also create
+# a Merge Request on https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests
+#
 :mailboxes:
-<%
-require "yaml"
-require "json"
-require_relative "lib/gitlab/redis" unless defined?(Gitlab::Redis)
+  <%
+    require_relative "lib/gitlab/mail_room" unless defined?(Gitlab::MailRoom)
+    config = Gitlab::MailRoom.config
 
-rails_env = ENV["RAILS_ENV"] || ENV["RACK_ENV"] || "development"
-
-config_file = ENV["MAIL_ROOM_GITLAB_CONFIG_FILE"] || "config/gitlab.yml"
-if File.exists?(config_file)
-  all_config = YAML.load_file(config_file)[rails_env]
-
-  config = all_config["incoming_email"] || {}
-  config['enabled']    = false    if config['enabled'].nil?
-  config['port']       = 143      if config['port'].nil?
-  config['ssl']        = false    if config['ssl'].nil?
-  config['start_tls']  = false    if config['start_tls'].nil?
-  config['mailbox']    = "inbox"  if config['mailbox'].nil?
-
-  if config['enabled'] && config['address']
-    redis_url = Gitlab::Redis.new(rails_env).url
-    %>
+    if Gitlab::MailRoom.enabled?
+  %>
     -
-      :host: <%= config['host'].to_json %>
-      :port: <%= config['port'].to_json %>
-      :ssl: <%= config['ssl'].to_json %>
-      :start_tls: <%= config['start_tls'].to_json %>
-      :email: <%= config['user'].to_json %>
-      :password: <%= config['password'].to_json %>
+      :host: <%= config[:host].to_json %>
+      :port: <%= config[:port].to_json %>
+      :ssl: <%= config[:ssl].to_json %>
+      :start_tls: <%= config[:start_tls].to_json %>
+      :email: <%= config[:user].to_json %>
+      :password: <%= config[:password].to_json %>
+      :idle_timeout: 60
 
-      :name: <%= config['mailbox'].to_json %>
+      :name: <%= config[:mailbox].to_json %>
 
       :delete_after_delivery: true
 
       :delivery_method: sidekiq
       :delivery_options:
-        :redis_url: <%= redis_url.to_json %>
-        :namespace: resque:gitlab
+        :redis_url: <%= config[:redis_url].to_json %>
+        :namespace: <%= Gitlab::Redis::SIDEKIQ_NAMESPACE %>
         :queue: incoming_email
         :worker: EmailReceiverWorker
 
       :arbitration_method: redis
       :arbitration_options:
-        :redis_url: <%= redis_url.to_json %>
-        :namespace: mail_room:gitlab
+        :redis_url: <%= config[:redis_url].to_json %>
+        :namespace: <%= Gitlab::Redis::MAILROOM_NAMESPACE %>
+
   <% end %>
-<% end %>
diff --git a/config/resque.yml.example b/config/resque.yml.example
index d98f43f71b2..0c19d8bc1d3 100644
--- a/config/resque.yml.example
+++ b/config/resque.yml.example
@@ -1,6 +1,34 @@
 # If you change this file in a Merge Request, please also create
 # a Merge Request on https://gitlab.com/gitlab-org/omnibus-gitlab/merge_requests
 #
-development: redis://localhost:6379
-test: redis://localhost:6379
-production: unix:/var/run/redis/redis.sock
+development:
+  url: redis://localhost:6379
+  # sentinels:
+  #   -
+  #     host: localhost
+  #     port: 26380 # point to sentinel, not to redis port
+  #   -
+  #     host: slave2
+  #     port: 26381 # point to sentinel, not to redis port
+test:
+  url: redis://localhost:6379
+production:
+  # Redis (single instance)
+  url: unix:/var/run/redis/redis.sock
+  ##
+  # Redis + Sentinel (for HA)
+  #
+  # Please read instructions carefully before using it as you may lose data:
+  # http://redis.io/topics/sentinel
+  #
+  # You must specify a list of a few sentinels that will handle client connection
+  # please read here for more information: https://docs.gitlab.com/ce/administration/high_availability/redis.html
+  ##
+  # url: redis://master:6379
+  # sentinels:
+  #   -
+  #     host: slave1
+  #     port: 26379 # point to sentinel, not to redis port
+  #   -
+  #     host: slave2
+  #     port: 26379 # point to sentinel, not to redis port
diff --git a/doc/administration/high_availability/redis.md b/doc/administration/high_availability/redis.md
index f6153216f33..bc424330656 100644
--- a/doc/administration/high_availability/redis.md
+++ b/doc/administration/high_availability/redis.md
@@ -1,7 +1,12 @@
 # Configuring Redis for GitLab HA
 
-You can choose to install and manage Redis yourself, or you can use GitLab
-Omnibus packages to help.
+You can choose to install and manage Redis yourself, or you can use the one
+that comes bundled with GitLab Omnibus packages.
+
+> **Note:** Redis does not require authentication by default. See
+  [Redis Security](http://redis.io/topics/security) documentation for more
+  information. We recommend using a combination of a Redis password and tight
+  firewall rules to secure your Redis service.
 
 ## Configure your own Redis server
 
@@ -9,49 +14,293 @@ If you're hosting GitLab on a cloud provider, you can optionally use a
 managed service for Redis. For example, AWS offers a managed ElastiCache service
 that runs Redis.
 
-> **Note:** Redis does not require authentication by default. See
-  [Redis Security](http://redis.io/topics/security) documentation for more
-  information. We recommend using a combination of a Redis password and tight
-  firewall rules to secure your Redis service.
+## Configure Redis using Omnibus
 
-## Configure using Omnibus
+If you don't want to bother setting up your own Redis server, you can use the
+one bundled with Omnibus. In this case, you should disable all services except
+Redis.
 
 1. Download/install GitLab Omnibus using **steps 1 and 2** from
    [GitLab downloads](https://about.gitlab.com/downloads). Do not complete other
    steps on the download page.
 1. Create/edit `/etc/gitlab/gitlab.rb` and use the following configuration.
    Be sure to change the `external_url` to match your eventual GitLab front-end
-   URL.
+   URL:
 
     ```ruby
-      external_url 'https://gitlab.example.com'
+    external_url 'https://gitlab.example.com'
 
-      # Disable all components except Redis
-      redis['enable'] = true
-      bootstrap['enable'] = false
-      nginx['enable'] = false
-      unicorn['enable'] = false
-      sidekiq['enable'] = false
-      postgresql['enable'] = false
-      gitlab_workhorse['enable'] = false
-      mailroom['enable'] = false
+    # Disable all services except Redis
+    redis['enable'] = true
+    bootstrap['enable'] = false
+    nginx['enable'] = false
+    unicorn['enable'] = false
+    sidekiq['enable'] = false
+    postgresql['enable'] = false
+    gitlab_workhorse['enable'] = false
+    mailroom['enable'] = false
 
-      # Redis configuration
-      redis['port'] = 6379
-      redis['bind'] = '0.0.0.0'
+    # Redis configuration
+    redis['port'] = 6379
+    redis['bind'] = '0.0.0.0'
 
-      # If you wish to use Redis authentication (recommended)
-      redis['password'] = 'Redis Password'
+    # If you wish to use Redis authentication (recommended)
+    redis['password'] = 'Redis Password'
     ```
 
 1. Run `sudo gitlab-ctl reconfigure` to install and configure PostgreSQL.
 
     > **Note**: This `reconfigure` step will result in some errors.
       That's OK - don't be alarmed.
+
 1. Run `touch /etc/gitlab/skip-auto-migrations` to prevent database migrations
    from running on upgrade. Only the primary GitLab application server should
    handle migrations.
 
+## Experimental Redis Sentinel support
+
+> [Introduced][ce-1877] in GitLab 8.11.
+
+Since GitLab 8.11, you can configure a list of Redis Sentinel servers that
+will monitor a group of Redis servers to provide you with a standard failover
+support.
+
+There is currently one exception to the Sentinel support: `mail_room`, the
+component that processes incoming emails. It doesn't support Sentinel yet, but
+we hope to integrate a future release that does support it.
+
+To get a better understanding on how to correctly setup Sentinel, please read
+the [Redis Sentinel documentation](http://redis.io/topics/sentinel) first, as
+failing to configure it correctly can lead to data loss.
+
+The configuration consists of three parts:
+
+- Redis setup
+- Sentinel setup
+- GitLab setup
+
+Read carefully how to configure those components below.
+
+### Redis setup
+
+You must have at least 2 Redis servers: 1 Master, 1 or more Slaves.
+They should be configured the same way and with similar server specs, as
+in a failover situation, any Slave can be elected as the new Master by
+the Sentinel servers.
+
+In a minimal setup, the only required change for the slaves in `redis.conf`
+is the addition of a `slaveof` line pointing to the initial master.
+You can increase the security by defining a `requirepass` configuration in
+the master, and `masterauth` in slaves.
+
+---
+
+**Configuring your own Redis server**
+
+1. Add to the slaves' `redis.conf`:
+
+    ```conf
+    # IP and port of the master Redis server
+    slaveof 10.10.10.10 6379
+    ```
+
+1. Optionally, set up password authentication for increased security.
+   Add the following to master's `redis.conf`:
+
+    ```conf
+    # Optional password authentication for increased security
+    requirepass "<password>"
+    ```
+
+1. Then add this line to all the slave servers' `redis.conf`:
+
+    ```conf
+    masterauth "<password>"
+    ```
+
+1. Restart the Redis services for the changes to take effect.
+
+---
+
+**Using Redis via Omnibus**
+
+1. Edit `/etc/gitlab/gitlab.rb` of a master Redis machine (usualy a single machine):
+
+    ```ruby
+    ## Redis TCP support (will disable UNIX socket transport)
+    redis['bind'] = '0.0.0.0' # or specify an IP to bind to a single one
+    redis['port'] = 6379
+
+    ## Master redis instance
+    redis['password'] = '<huge password string here>'
+    ```
+
+1. Edit `/etc/gitlab/gitlab.rb` of a slave Redis machine (should be one or more machines):
+
+    ```ruby
+    ## Redis TCP support (will disable UNIX socket transport)
+    redis['bind'] = '0.0.0.0' # or specify an IP to bind to a single one
+    redis['port'] = 6379
+
+    ## Slave redis instance
+    redis['master_ip'] = '10.10.10.10' # IP of master Redis server
+    redis['master_port'] = 6379 # Port of master Redis server
+    redis['master_password'] = "<huge password string here>"
+    ```
+
+1. Reconfigure the GitLab for the changes to take effect: `sudo gitlab-ctl reconfigure`
+
+---
+
+Now that the Redis servers are all set up, let's configure the Sentinel
+servers.
+
+### Sentinel setup
+
+We don't provide yet an automated way to setup and run the Sentinel daemon
+from Omnibus installation method. You must follow the instructions below and
+run it by yourself.
+
+The support for Sentinel in Ruby has some [caveats](https://github.com/redis/redis-rb/issues/531).
+While you can give any name for the `master-group-name` part of the
+configuration, as in this example:
+
+```conf
+sentinel monitor <master-group-name> <ip> <port> <quorum>
+```
+
+,for it to work in Ruby, you have to use the "hostname" of the master Redis
+server, otherwise you will get an error message like:
+`Redis::CannotConnectError: No sentinels available.`. Read
+[Sentinel troubleshooting](#sentinel-troubleshooting) for more information.
+
+Here is an example configuration file (`sentinel.conf`) for a Sentinel node:
+
+```conf
+port 26379
+sentinel monitor master-redis.example.com 10.10.10.10 6379 1
+sentinel down-after-milliseconds master-redis.example.com 10000
+sentinel config-epoch master-redis.example.com 0
+sentinel leader-epoch master-redis.example.com 0
+```
+
+---
+
+The final part is to inform the main GitLab application server of the Redis
+master and the new sentinels servers.
+
+### GitLab setup
+
+You can enable or disable sentinel support at any time in new or existing
+installations. From the GitLab application perspective, all it requires is
+the correct credentials for the master Redis and for a few Sentinel nodes.
+
+It doesn't require a list of all Sentinel nodes, as in case of a failure,
+the application will need to query only one of them.
+
+>**Note:**
+The following steps should be performed in the [GitLab application server](gitlab.md).
+
+**For source based installations**
+
+1. Edit `/home/git/gitlab/config/resque.yml` following the example in
+   `/home/git/gitlab/config/resque.yml.example`, and uncomment the sentinels
+   line, changing to the correct server credentials.
+1. Restart GitLab for the changes to take effect.
+
+**For Omnibus installations**
+
+1. Edit `/etc/gitlab/gitlab.rb` and add/change the following lines:
+
+    ```ruby
+    gitlab-rails['redis_host'] = "master-redis.example.com"
+    gitlab-rails['redis_port'] = 6379
+    gitlab-rails['redis_password'] = '<huge password string here>'
+    gitlab-rails['redis_sentinels'] = [
+      {'host' => '10.10.10.1', 'port' => 26379},
+      {'host' => '10.10.10.2', 'port' => 26379},
+      {'host' => '10.10.10.3', 'port' => 26379}
+    ]
+    ```
+
+1. [Reconfigure] the GitLab for the changes to take effect.
+
+### Sentinel troubleshooting
+
+If you get an error like: `Redis::CannotConnectError: No sentinels available.`,
+there may be something wrong with your configuration files or it can be related
+to [this issue][gh-531] ([pull request][gh-534] that should make things better).
+
+It's a bit rigid the way you have to config `resque.yml` and `sentinel.conf`,
+otherwise `redis-rb` will not work properly.
+
+The hostname ('my-primary-redis') of the primary Redis server (`sentinel.conf`)
+**must** match the one configured in GitLab (`resque.yml` for source installations
+or `gitlab-rails['redis_*']` in Omnibus) and it must be valid ex:
+
+```conf
+# sentinel.conf:
+sentinel monitor my-primary-redis 10.10.10.10 6379 1
+sentinel down-after-milliseconds my-primary-redis 10000
+sentinel config-epoch my-primary-redis 0
+sentinel leader-epoch my-primary-redis 0
+```
+
+```yaml
+# resque.yaml
+production:
+  url: redis://my-primary-redis:6378
+  sentinels:
+    -
+      host: slave1
+      port: 26380 # point to sentinel, not to redis port
+    -
+      host: slave2
+      port: 26381 # point to sentinel, not to redis port
+```
+
+When in doubt, please read [Redis Sentinel documentation](http://redis.io/topics/sentinel)
+
+---
+
+To make sure your configuration is correct:
+
+1. SSH into your GitLab application server
+1. Enter the Rails console:
+
+    ```
+    # For Omnibus installations
+    sudo gitlab-rails console
+
+    # For source installations
+    sudo -u git rails console RAILS_ENV=production
+    ```
+
+1. Run in the console:
+
+    ```ruby
+    redis = Redis.new(Gitlab::Redis.params)
+    redis.info
+    ```
+
+    Keep this screen open and try to simulate a failover below.
+
+1. To simulate a failover on master Redis, SSH into the Redis server and run:
+
+    ```bash
+    # port must match your master redis port
+     redis-cli -h localhost -p 6379 DEBUG sleep 60
+    ```
+
+1. Then back in the Rails console from the first step, run:
+
+    ```
+    redis.info
+    ```
+
+    You should see a different port after a few seconds delay
+    (the failover/reconnect time).
+
 ---
 
 Read more on high-availability configuration:
@@ -60,3 +309,9 @@ Read more on high-availability configuration:
 1. [Configure NFS](nfs.md)
 1. [Configure the GitLab application servers](gitlab.md)
 1. [Configure the load balancers](load_balancer.md)
+
+[ce-1877]: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/1877
+[restart]: ../restart_gitlab.md#installations-from-source
+[reconfigure]: ../restart_gitlab.md#omnibus-gitlab-reconfigure
+[gh-531]: https://github.com/redis/redis-rb/issues/531
+[gh-534]: https://github.com/redis/redis-rb/issues/534
diff --git a/doc/install/installation.md b/doc/install/installation.md
index af8e31a705b..acf294b397d 100644
--- a/doc/install/installation.md
+++ b/doc/install/installation.md
@@ -588,15 +588,17 @@ for the changes to take effect.
 
 ### Custom Redis Connection
 
-If you'd like Resque to connect to a Redis server on a non-standard port or on a different host, you can configure its connection string via the `config/resque.yml` file.
+If you'd like to connect to a Redis server on a non-standard port or on a different host, you can configure its connection string via the `config/resque.yml` file.
 
     # example
-    production: redis://redis.example.tld:6379
+    production: 
+      url: redis://redis.example.tld:6379
 
 If you want to connect the Redis server via socket, then use the "unix:" URL scheme and the path to the Redis socket file in the `config/resque.yml` file.
 
     # example
-    production: unix:/path/to/redis/socket
+    production: 
+      url: unix:/path/to/redis/socket
 
 ### Custom SSH Connection
 
diff --git a/lib/gitlab/mail_room.rb b/lib/gitlab/mail_room.rb
new file mode 100644
index 00000000000..12999a90a29
--- /dev/null
+++ b/lib/gitlab/mail_room.rb
@@ -0,0 +1,47 @@
+require 'yaml'
+require 'json'
+require_relative 'redis' unless defined?(Gitlab::Redis)
+
+module Gitlab
+  module MailRoom
+    class << self
+      def enabled?
+        config[:enabled] && config[:address]
+      end
+
+      def config
+        @config ||= fetch_config
+      end
+
+      def reset_config!
+        @config = nil
+      end
+
+      private
+
+      def fetch_config
+        return {} unless File.exist?(config_file)
+
+        rails_env = ENV['RAILS_ENV'] || ENV['RACK_ENV'] || 'development'
+        all_config = YAML.load_file(config_file)[rails_env].deep_symbolize_keys
+
+        config = all_config[:incoming_email] || {}
+        config[:enabled] = false if config[:enabled].nil?
+        config[:port] = 143 if config[:port].nil?
+        config[:ssl] = false if config[:ssl].nil?
+        config[:start_tls] = false if config[:start_tls].nil?
+        config[:mailbox] = 'inbox' if config[:mailbox].nil?
+
+        if config[:enabled] && config[:address]
+          config[:redis_url] = Gitlab::Redis.new(rails_env).url
+        end
+
+        config
+      end
+
+      def config_file
+        ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] || File.expand_path('../../../config/gitlab.yml', __FILE__)
+      end
+    end
+  end
+end
diff --git a/lib/gitlab/redis.rb b/lib/gitlab/redis.rb
index 1f92986ec9a..9376b54f43b 100644
--- a/lib/gitlab/redis.rb
+++ b/lib/gitlab/redis.rb
@@ -1,50 +1,94 @@
+# This file should not have any direct dependency on Rails environment
+# please require all dependencies below:
+require 'active_support/core_ext/hash/keys'
+
 module Gitlab
   class Redis
     CACHE_NAMESPACE = 'cache:gitlab'
     SESSION_NAMESPACE = 'session:gitlab'
     SIDEKIQ_NAMESPACE = 'resque:gitlab'
-
-    attr_reader :url
+    MAILROOM_NAMESPACE = 'mail_room:gitlab'
+    DEFAULT_REDIS_URL = 'redis://localhost:6379'
 
     # To be thread-safe we must be careful when writing the class instance
     # variables @url and @pool. Because @pool depends on @url we need two
     # mutexes to prevent deadlock.
-    URL_MUTEX = Mutex.new
+    PARAMS_MUTEX = Mutex.new
     POOL_MUTEX = Mutex.new
-    private_constant :URL_MUTEX, :POOL_MUTEX
+    private_constant :PARAMS_MUTEX, :POOL_MUTEX
 
-    def self.url
-      @url || URL_MUTEX.synchronize { @url = new.url }
-    end
+    class << self
+      def params
+        @params || PARAMS_MUTEX.synchronize { @params = new.params }
+      end
+
+      # @deprecated Use .params instead to get sentinel support
+      def url
+        new.url
+      end
 
-    def self.with
-      if @pool.nil?
-        POOL_MUTEX.synchronize do
-          @pool = ConnectionPool.new { ::Redis.new(url: url) }
+      def with
+        if @pool.nil?
+          POOL_MUTEX.synchronize do
+            @pool = ConnectionPool.new { ::Redis.new(params) }
+          end
         end
+        @pool.with { |redis| yield redis }
       end
-      @pool.with { |redis| yield redis }
+
+      def reset_params!
+        @params = nil
+      end
+    end
+
+    def initialize(rails_env = nil)
+      @rails_env = rails_env || ::Rails.env
     end
 
-    def self.redis_store_options
-      url = new.url
-      redis_config_hash = ::Redis::Store::Factory.extract_host_options_from_uri(url)
-      # Redis::Store does not handle Unix sockets well, so let's do it for them
-      redis_uri = URI.parse(url)
+    def params
+      redis_store_options
+    end
+
+    def url
+      raw_config_hash[:url]
+    end
+
+    private
+
+    def redis_store_options
+      config = raw_config_hash
+      redis_url = config.delete(:url)
+      redis_uri = URI.parse(redis_url)
+
       if redis_uri.scheme == 'unix'
-        redis_config_hash[:path] = redis_uri.path
+        # Redis::Store does not handle Unix sockets well, so let's do it for them
+        config[:path] = redis_uri.path
+        config
+      else
+        redis_hash = ::Redis::Store::Factory.extract_host_options_from_uri(redis_url)
+        # order is important here, sentinels must be after the connection keys.
+        # {url: ..., port: ..., sentinels: [...]}
+        redis_hash.merge(config)
       end
-      redis_config_hash
     end
 
-    def initialize(rails_env = nil)
-      rails_env ||= Rails.env
-      config_file = File.expand_path('../../../config/resque.yml', __FILE__)
+    def raw_config_hash
+      config_data = fetch_config
 
-      @url = "redis://localhost:6379"
-      if File.exist?(config_file)
-        @url = YAML.load_file(config_file)[rails_env]
+      if config_data
+        config_data.is_a?(String) ? { url: config_data } : config_data.deep_symbolize_keys
+      else
+        { url: DEFAULT_REDIS_URL }
       end
     end
+
+    def fetch_config
+      file = config_file
+      File.exist?(file) ? YAML.load_file(file)[@rails_env] : false
+    end
+
+    def config_file
+      File.expand_path('../../../config/resque.yml', __FILE__)
+    end
   end
 end
diff --git a/spec/config/mail_room_spec.rb b/spec/config/mail_room_spec.rb
index 6fad7e2b9e7..c5d3cd70acc 100644
--- a/spec/config/mail_room_spec.rb
+++ b/spec/config/mail_room_spec.rb
@@ -1,53 +1,48 @@
-require "spec_helper"
+require 'spec_helper'
 
-describe "mail_room.yml" do
-  let(:config_path)   { "config/mail_room.yml" }
+describe 'mail_room.yml' do
+  let(:config_path)   { 'config/mail_room.yml' }
   let(:configuration) { YAML.load(ERB.new(File.read(config_path)).result) }
 
-  context "when incoming email is disabled" do
+  context 'when incoming email is disabled' do
     before do
-      ENV["MAIL_ROOM_GITLAB_CONFIG_FILE"] = Rails.root.join("spec/fixtures/mail_room_disabled.yml").to_s
+      ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] = Rails.root.join('spec/fixtures/mail_room_disabled.yml').to_s
+      Gitlab::MailRoom.reset_config!
     end
 
     after do
-      ENV["MAIL_ROOM_GITLAB_CONFIG_FILE"] = nil
+      ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] = nil
     end
 
-    it "contains no configuration" do
+    it 'contains no configuration' do
       expect(configuration[:mailboxes]).to be_nil
     end
   end
 
-  context "when incoming email is enabled" do
+  context 'when incoming email is enabled' do
     before do
-      ENV["MAIL_ROOM_GITLAB_CONFIG_FILE"] = Rails.root.join("spec/fixtures/mail_room_enabled.yml").to_s
+      ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] = Rails.root.join('spec/fixtures/mail_room_enabled.yml').to_s
+      Gitlab::MailRoom.reset_config!
     end
 
     after do
-      ENV["MAIL_ROOM_GITLAB_CONFIG_FILE"] = nil
+      ENV['MAIL_ROOM_GITLAB_CONFIG_FILE'] = nil
     end
 
-    it "contains the intended configuration" do
+    it 'contains the intended configuration' do
       expect(configuration[:mailboxes].length).to eq(1)
 
       mailbox = configuration[:mailboxes].first
 
-      expect(mailbox[:host]).to eq("imap.gmail.com")
+      expect(mailbox[:host]).to eq('imap.gmail.com')
       expect(mailbox[:port]).to eq(993)
       expect(mailbox[:ssl]).to eq(true)
       expect(mailbox[:start_tls]).to eq(false)
-      expect(mailbox[:email]).to eq("gitlab-incoming@gmail.com")
-      expect(mailbox[:password]).to eq("[REDACTED]")
-      expect(mailbox[:name]).to eq("inbox")
-
-      redis_config_file = Rails.root.join('config', 'resque.yml')
-
-      redis_url =
-        if File.exist?(redis_config_file)
-          YAML.load_file(redis_config_file)[Rails.env]
-        else
-          "redis://localhost:6379"
-        end
+      expect(mailbox[:email]).to eq('gitlab-incoming@gmail.com')
+      expect(mailbox[:password]).to eq('[REDACTED]')
+      expect(mailbox[:name]).to eq('inbox')
+
+      redis_url = Gitlab::Redis.url
 
       expect(mailbox[:delivery_options][:redis_url]).to eq(redis_url)
       expect(mailbox[:arbitration_options][:redis_url]).to eq(redis_url)
diff --git a/spec/fixtures/config/redis_new_format_host.yml b/spec/fixtures/config/redis_new_format_host.yml
new file mode 100644
index 00000000000..13772677a45
--- /dev/null
+++ b/spec/fixtures/config/redis_new_format_host.yml
@@ -0,0 +1,29 @@
+# redis://[:password@]host[:port][/db-number][?option=value]
+# more details: http://www.iana.org/assignments/uri-schemes/prov/redis
+development:
+  url: redis://:mynewpassword@localhost:6379/99
+  sentinels:
+    -
+      host: localhost
+      port: 26380 # point to sentinel, not to redis port
+    -
+      host: slave2
+      port: 26381 # point to sentinel, not to redis port
+test:
+  url: redis://:mynewpassword@localhost:6379/99
+  sentinels:
+    -
+      host: localhost
+      port: 26380 # point to sentinel, not to redis port
+    -
+      host: slave2
+      port: 26381 # point to sentinel, not to redis port
+production:
+  url: redis://:mynewpassword@localhost:6379/99
+  sentinels:
+    -
+      host: slave1
+      port: 26380 # point to sentinel, not to redis port
+    -
+      host: slave2
+      port: 26381 # point to sentinel, not to redis port
diff --git a/spec/fixtures/config/redis_new_format_socket.yml b/spec/fixtures/config/redis_new_format_socket.yml
new file mode 100644
index 00000000000..4e76830c281
--- /dev/null
+++ b/spec/fixtures/config/redis_new_format_socket.yml
@@ -0,0 +1,6 @@
+development:
+  url: unix:/path/to/redis.sock
+test:
+  url: unix:/path/to/redis.sock
+production:
+  url: unix:/path/to/redis.sock
diff --git a/spec/fixtures/config/redis_old_format_host.yml b/spec/fixtures/config/redis_old_format_host.yml
new file mode 100644
index 00000000000..253d0a994f5
--- /dev/null
+++ b/spec/fixtures/config/redis_old_format_host.yml
@@ -0,0 +1,5 @@
+# redis://[:password@]host[:port][/db-number][?option=value]
+# more details: http://www.iana.org/assignments/uri-schemes/prov/redis
+development: redis://:mypassword@localhost:6379/99
+test: redis://:mypassword@localhost:6379/99
+production: redis://:mypassword@localhost:6379/99
diff --git a/spec/fixtures/config/redis_old_format_socket.yml b/spec/fixtures/config/redis_old_format_socket.yml
new file mode 100644
index 00000000000..fd31ce8ea3d
--- /dev/null
+++ b/spec/fixtures/config/redis_old_format_socket.yml
@@ -0,0 +1,3 @@
+development: unix:/path/to/old/redis.sock
+test: unix:/path/to/old/redis.sock
+production: unix:/path/to/old/redis.sock
diff --git a/spec/lib/gitlab/redis_spec.rb b/spec/lib/gitlab/redis_spec.rb
new file mode 100644
index 00000000000..879ed30841c
--- /dev/null
+++ b/spec/lib/gitlab/redis_spec.rb
@@ -0,0 +1,80 @@
+require 'spec_helper'
+
+describe Gitlab::Redis do
+  let(:redis_config) { Rails.root.join('config', 'resque.yml').to_s }
+
+  before(:each) { described_class.reset_params! }
+  after(:each) { described_class.reset_params! }
+
+  describe '.params' do
+    subject { described_class.params }
+
+    context 'when url contains unix socket reference' do
+      let(:config_old) { Rails.root.join('spec/fixtures/config/redis_old_format_socket.yml').to_s }
+      let(:config_new) { Rails.root.join('spec/fixtures/config/redis_new_format_socket.yml').to_s }
+
+      context 'with old format' do
+        it 'returns path key instead' do
+          expect_any_instance_of(described_class).to receive(:config_file) { config_old }
+
+          is_expected.to include(path: '/path/to/old/redis.sock')
+          is_expected.not_to have_key(:url)
+        end
+      end
+
+      context 'with new format' do
+        it 'returns path key instead' do
+          expect_any_instance_of(described_class).to receive(:config_file) { config_new }
+
+          is_expected.to include(path: '/path/to/redis.sock')
+          is_expected.not_to have_key(:url)
+        end
+      end
+    end
+
+    context 'when url is host based' do
+      let(:config_old) { Rails.root.join('spec/fixtures/config/redis_old_format_host.yml') }
+      let(:config_new) { Rails.root.join('spec/fixtures/config/redis_new_format_host.yml') }
+
+      context 'with old format' do
+        it 'returns hash with host, port, db, and password' do
+          expect_any_instance_of(described_class).to receive(:config_file) { config_old }
+
+          is_expected.to include(host: 'localhost', password: 'mypassword', port: 6379, db: 99)
+          is_expected.not_to have_key(:url)
+        end
+      end
+
+      context 'with new format' do
+        it 'returns hash with host, port, db, and password' do
+          expect_any_instance_of(described_class).to receive(:config_file) { config_new }
+
+          is_expected.to include(host: 'localhost', password: 'mynewpassword', port: 6379, db: 99)
+          is_expected.not_to have_key(:url)
+        end
+      end
+    end
+  end
+
+  describe '#raw_config_hash' do
+    it 'returns default redis url when no config file is present' do
+      expect(subject).to receive(:fetch_config) { false }
+
+      expect(subject.send(:raw_config_hash)).to eq(url: Gitlab::Redis::DEFAULT_REDIS_URL)
+    end
+
+    it 'returns old-style single url config in a hash' do
+      expect(subject).to receive(:fetch_config) { 'redis://myredis:6379' }
+      expect(subject.send(:raw_config_hash)).to eq(url: 'redis://myredis:6379')
+    end
+
+  end
+
+  describe '#fetch_config' do
+    it 'returns false when no config file is present' do
+      allow(File).to receive(:exist?).with(redis_config) { false }
+
+      expect(subject.send(:fetch_config)).to be_falsey
+    end
+  end
+end