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

Gemfile

@@ -26,6 +26,7 @@ gem 'doorkeeper'
 gem 'fast_blank'
 gem 'goldfinger'
 gem 'hiredis'
+gem 'redis-namespace'
 gem 'htmlentities'
 gem 'http'
 gem 'http_accept_language'

Gemfile.lock

@@ -340,9 +340,11 @@ GEM
     redis-activesupport (5.0.2)
       activesupport (>= 3, < 6)
       redis-store (~> 1.3.0)
+    redis-namespace (1.5.3)
+      redis (~> 3.0, >= 3.0.4)
+      redis-store (>= 1.2, < 1.4)
     redis-rack (2.0.2)
       rack (>= 1.5, < 3)
-      redis-store (>= 1.2, < 1.4)
     redis-rails (5.0.2)
       redis-actionpack (>= 5.0, < 6)
       redis-activesupport (>= 5.0, < 6)
@@ -524,6 +526,7 @@ DEPENDENCIES
   rails-settings-cached
   rails_12factor
   redis (~> 3.2)
+  redis-namespace
   redis-rails
   rqrcode
   rspec-rails

config/initializers/redis.rb

@@ -9,14 +9,21 @@
   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
 )
 
+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'], {
-    namespace: 'cache',
-    expires_in: 10.minutes,
-  }
+  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

streaming/index.js

@@ -87,13 +87,21 @@ if (cluster.isMaster) {
   const pgPool = new pg.Pool(Object.assign(pgConfigs[env], dbUrlToConfig(process.env.DATABASE_URL)))
   const server = http.createServer(app)
   const wss    = new WebSocket.Server({ server })
+  const redisNamespace = process.env.REDIS_NAMESPACE || null
 
-  const redisClient = redis.createClient({
+  const redisParams = {
     host:     process.env.REDIS_HOST     || '127.0.0.1',
     port:     process.env.REDIS_PORT     || 6379,
     password: process.env.REDIS_PASSWORD,
     url:      process.env.REDIS_URL      || null
-  })
+  }
+
+  if (redisNamespace) {
+    redisParams.namespace = redisNamespace
+  }
+  const redisPrefix = redisNamespace ? `${redisNamespace}:` : ''
+
+  const redisClient = redis.createClient(redisParams)
 
   const subs = {}
 
@@ -105,11 +113,10 @@ if (cluster.isMaster) {
     if (!callbacks) {
       return
     }
-
     callbacks.forEach(callback => callback(message))
   })
 
-  redisClient.psubscribe('timeline:*')
+  redisClient.psubscribe(`${redisPrefix}timeline:*`)
 
   const subscribe = (channel, callback) => {
     log.silly(`Adding listener for ${channel}`)
@@ -242,8 +249,8 @@ if (cluster.isMaster) {
       }
     }
 
-    subscribe(id, listener)
-    attachCloseHandler(id, listener)
+    subscribe(`${redisPrefix}${id}`, listener)
+    attachCloseHandler(`${redisPrefix}${id}`, listener)
   }
 
   // Setup stream output to HTTP