Override master db selection for splitting read write queries in rails

Question

To distribute load and improve the database performance, I am trying to split read-write queries with some custom modification. I am using makara(https://github.com/instacart/makara) gem for the same in my Rails application. The same is working fine for splitting read-write queries to master and slave. I need to modify the master db selection by checking the replication lag with some custom condition.

I have defined a custom proxy class(as mentioned in documentation) in config/initializers directory but same does not seem to work.

class MyAwesomeSqlProxy < ::Makara::Proxy
  hijack_method :select, :ping
  send_to_all :connect, :reconnect, :disconnect, :clear_cache

  def connection_for(config)
    ::Sql::Client.new(config)
  end

  def needs_master?(method_name, args)
    return false if args.empty?
    sql = args.first
    sql !~ /^select/i
  end
end

When I make any changes in needs_master? method, same is not reflecting while running the query. I am not sure if I am defining it at the wrong place or this class needs to be loaded somewhere explicitly.