This has some minor changes from the original as `fully_replicated` is set to `true` and the key `followers` under `optopus/environments` is removed

full_replicated_shards.yml

<%
require 'cgi'
require 'uri'

def attribute(name, value, force_string = false)
  if value
    value_string =
      if force_string
        '"' + value + '"'
      else
        value
      end
    "#{name}: #{value_string}"
  else
    ""
  end
end

configs = case Rails.env
when 'development', 'test'
  # use dev and test DB as feaux 'follower'
  Array.new(2){YAML::load_file(File.open("config/database.yml"))[Rails.env]}
else
  # staging, production, etc with Heroku config vars for follower DBs
  master_url = ENV['DATABASE_URL']
  slave_keys = ENV.keys.select{|k| k =~ /HEROKU_POSTGRESQL_.*_URL/}
  slave_keys.delete_if{ |k| ENV[k] == master_url }

  slave_keys.map do |env_key|
    config = {}
    begin
      uri = URI.parse(ENV["#{env_key}"])
    rescue URI::InvalidURIError
      raise "Invalid DATABASE_URL"
    end

    raise "No RACK_ENV or RAILS_ENV found" unless ENV["RAILS_ENV"] || ENV["RACK_ENV"]
    config['color'] = env_key.match(/HEROKU_POSTGRESQL_(.*)_URL/)[1].downcase
    config['adapter'] = uri.scheme
    config['adapter'] = "postgresql" if config['adapter'] == "postgres"

    config['database'] = (uri.path || "").split("/")[1]

    config['username'] = uri.user
    config['password'] = uri.password

    config['host'] = uri.host
    config['port'] = uri.port

    config['params'] = CGI.parse(uri.query || "")
    config
  end
end

whitelist = ENV['SLAVE_ENABLED_FOLLOWERS' ].downcase.split(/ *, */) rescue nil
blacklist = ENV['SLAVE_DISABLED_FOLLOWERS'].downcase.split(/ *, */) rescue nil

configs.delete_if do |c|
  ( whitelist && !c['color'].in?(whitelist) ) || ( blacklist && c['color'].in?(blacklist) )
end
%>
octopus:
  replicated:       true
  fully_replicated: true
  environments:
  <% if configs.present? %>
    <%= "- #{ENV["RAILS_ENV"] || ENV["RACK_ENV"] || Rails.env}" %>
  <%= ENV["RAILS_ENV"] || ENV["RACK_ENV"] || Rails.env %>:
    <% configs.each_with_index do |c, i| %>
    <%= c.has_key?('color') ? "#{c['color']}_follower" : "follower_#{i + 1}" %>:
      <%= attribute "adapter",  c['adapter'] %>
      <%= attribute "database", c['database'] %>
      <%= attribute "username", c['username'] %>
      <%= attribute "password", c['password'], true %>
      <%= attribute "host",     c['host'] %>
      <%= attribute "port",     c['port'] %>
      <% (c['params'] || {}).each do |key, value| %>
      <%= key %>: <%= value.first %>
      <% end %>
    <% end %>
  <% else %>
    - none
  <% end %>