Add Makara dependency to support read-replicas (#8216)

Not active by default unless config/database.yml is edited

Gemfile

@@ -10,6 +10,7 @@ gem 'rails', '~> 5.2.1'
 
 gem 'hamlit-rails', '~> 0.2'
 gem 'pg', '~> 1.0'
+gem 'makara', '~> 0.4'
 gem 'pghero', '~> 2.1'
 gem 'dotenv-rails', '~> 2.2', '< 2.3'
 

Gemfile.lock

@@ -322,6 +322,8 @@ GEM
       nokogiri (>= 1.5.9)
     mail (2.7.0)
       mini_mime (>= 0.1.1)
+    makara (0.4.0)
+      activerecord (>= 3.0.0)
     marcel (0.3.2)
       mimemagic (~> 0.3.2)
     mario-redis-lock (1.2.1)
@@ -697,6 +699,7 @@ DEPENDENCIES
   letter_opener_web (~> 1.3)
   link_header (~> 0.0)
   lograge (~> 0.10)
+  makara (~> 0.4)
   mario-redis-lock (~> 1.2)
   memory_profiler
   microformats (~> 4.0)