anchor.diff:  %%--------------------------------------------------------------------
   %%% Internal functions
   %%--------------------------------------------------------------------
  -lookup_urls() ->
  +logs_redis_urls() ->
       URLs = case os:getenv("LOGPLEX_SHARD_URLS") of
                  [] ->
                      case os:getenv("LOGPLEX_CONFIG_REDIS_URL") of
  
positive.code: %%--------------------------------------------------------------------
  init([]) ->
      ?INFO("at=init", []),
      Urls = lookup_urls(),
  
      erlang:process_flag(trap_exit, true),
  
  
negative.code: prepare_new_urls(NewIps) ->
      NewIpsSorted = lists:sort(NewIps),
      OldUrls = lists:sort([binary_to_list(Url)
                            || Url <- urls()]),
      length(OldUrls) =:= length(NewIpsSorted)
          orelse erlang:error({invalid_ip_list, different_length_to_existing}),
      NewUrls = [ update_redis_host(OldUrl, NewIp)
  