namespace redis usage (#2869)

* add redis-namespace gem

* namespace redis usage

* refactor redis namespace code to be less intrusive

previously : would be prepended to keys when the
REDIS_NAMESPACE env var was not set

now if it is not set the namespacing functions are
not used at all, which should prevent disruptions
when instances update.

* fix redis namespace variable style in streaming js

* remove trailing space

* final redis namespace style fix

config/initializers/redis.rb

@@ -9,14 +9,21 @@ if ENV['REDIS_URL'].blank?
   ENV['REDIS_URL'] = "redis://#{password.blank? ? '' : ":#{password}@"}#{host}:#{port}/#{db}"
 end
 
-Redis.current = Redis.new(
+redis_connection = Redis.new(
   url: ENV['REDIS_URL'],
   driver: :hiredis
 )
 
-Rails.application.configure do
-  config.cache_store = :redis_store, ENV['REDIS_URL'], {
-    namespace: 'cache',
-    expires_in: 10.minutes,
-  }
+cache_params = { expires_in: 10.minutes }
+
+namespace = ENV.fetch('REDIS_NAMESPACE') { nil }
+if namespace
+  Redis.current = Redis::Namespace.new(namespace, :redis => redis_connection)
+  cache_params[:namespace] = namespace + '_cache'
+else
+  Redis.current = redis_connection
+end
+
+Rails.application.configure do
+  config.cache_store = :redis_store, ENV['REDIS_URL'], cache_params
 end

config/initializers/sidekiq.rb

@@ -1,9 +1,16 @@
 # frozen_string_literal: true
 
+namespace = ENV.fetch('REDIS_NAMESPACE') { nil }
+redis_params = { url: ENV['REDIS_URL'] }
+
+if namespace
+  redis_params [:namespace] = namespace
+end
+
 Sidekiq.configure_server do |config|
-  config.redis = { url: ENV['REDIS_URL'] }
+  config.redis = redis_params
 end
 
 Sidekiq.configure_client do |config|
-  config.redis = { url: ENV['REDIS_URL'] }
+  config.redis = redis_params
 end