erldns

%% Copyright (c) 2012-2020, DNSimple Corporation
%%
%% Permission to use, copy, modify, and/or distribute this software for any
%% purpose with or without fee is hereby granted, provided that the above
%% copyright notice and this permission notice appear in all copies.
%%
%% THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
%% WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
%% MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
%% ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
%% WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
%% ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
%% OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

%% @doc The erldns OTP application.
-module(erldns_app).

-behavior(application).

% Application hooks
-export([
    start/2,
    start_phase/3,
    stop/1
]).

start(_Type, _Args) ->
    lager:info("Starting erldns application"),
    setup_metrics(),
    nodefinder:multicast_start(),
    Ret = erldns_sup:start_link(),
    erldns_metrics:maybe_start(),
    erldns_admin:maybe_start(),
    Ret.

start_phase(post_start, _StartType, _PhaseArgs) ->
    erldns_events:add_handler(erldns_event_handler),

    case application:get_env(erldns, custom_zone_parsers) of
        {ok, Parsers} ->
            erldns_zone_parser:register_parsers(Parsers);
        _ ->
            ok
    end,

    case application:get_env(erldns, custom_zone_encoders) of
        {ok, Encoders} ->
            erldns_zone_encoder:register_encoders(Encoders);
        _ ->
            ok
    end,

    lager:info("Loading zones from local file"),
    erldns_zone_loader:load_zones(),

    lager:info("Notifying servers to start"),
    erldns_events:notify({?MODULE, start_servers}),

    ok.

stop(_State) ->
    lager:info("Stop erldns application"),
    ok.

setup_metrics() ->
    folsom_metrics:new_counter(udp_request_counter),
    folsom_metrics:new_counter(tcp_request_counter),
    folsom_metrics:new_meter(udp_request_meter),
    folsom_metrics:new_meter(tcp_request_meter),

    folsom_metrics:new_meter(udp_error_meter),
    folsom_metrics:new_meter(tcp_error_meter),
    folsom_metrics:new_history(udp_error_history),
    folsom_metrics:new_history(tcp_error_history),

    folsom_metrics:new_meter(refused_response_meter),
    folsom_metrics:new_counter(refused_response_counter),

    folsom_metrics:new_meter(empty_response_meter),
    folsom_metrics:new_counter(empty_response_counter),

    folsom_metrics:new_histogram(udp_handoff_histogram),
    folsom_metrics:new_histogram(tcp_handoff_histogram),

    folsom_metrics:new_counter(request_throttled_counter),
    folsom_metrics:new_meter(request_throttled_meter),
    folsom_metrics:new_histogram(request_handled_histogram),

    folsom_metrics:new_counter(packet_dropped_empty_queue_counter),
    folsom_metrics:new_meter(packet_dropped_empty_queue_meter),

    folsom_metrics:new_counter(worker_timeout_counter),
    folsom_metrics:new_meter(worker_timeout_meter),

    folsom_metrics:new_meter(cache_hit_meter),
    folsom_metrics:new_meter(cache_expired_meter),
    folsom_metrics:new_meter(cache_miss_meter),

    folsom_metrics:new_counter(dnssec_request_counter),
    folsom_metrics:new_meter(dnssec_request_meter),

    folsom_metrics:new_counter(erldns_handler_error_counter),
    folsom_metrics:new_meter(erldns_handler_error_meter).