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%% Copyright (c) 2011-2017, Loïc Hoguin <essen@ninenines.eu>
%%
%% 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.
%% Handler middleware.
%%
%% Execute the handler given by the <em>handler</em> and <em>handler_opts</em>
%% environment values. The result of this execution is added to the
%% environment under the <em>result</em> value.
-module(dreki_web_handler).
-include_lib("opentelemetry_api/include/otel_tracer.hrl").
-behaviour(cowboy_middleware).
-export([execute/2]).
-export([terminate/4]).
-callback init(Req, any())
-> {ok | module(), Req, any()}
| {module(), Req, any(), any()}
when Req::cowboy_req:req().
-callback terminate(any(), map(), any()) -> ok.
-optional_callbacks([terminate/3]).
-spec execute(Req, Env) -> {ok, Req, Env}
when Req::cowboy_req:req(), Env::cowboy_middleware:env().
execute(Req, Env=#{handler := Handler}) ->
Headers = maps:get(headers, Req),
otel_propagator_text_map:extract(maps:to_list(Headers)),
HandlerB = atom_to_binary(Handler),
Method = maps:get(method, Req),
Attributes = [
{'http.host', maps:get(host, Req)},
{'http.host.port', maps:get(port, Req)},
{'http.method', Method},
{'http.scheme', maps:get(scheme, Req)},
{'http.target', maps:get(path, Req)},
{'http.user_agent', maps:get(<<"user-agent">>, Headers, <<"">>)}
],
SpanName = iolist_to_binary([<<"HTTP ">>, Method, <<" ">>, HandlerB]),
logger:debug("SpanName: ~p", [SpanName]),
?with_span(SpanName, #{}, fun(Ctx) -> execute_(Req, Env, Ctx) end).
execute_(Req0, Env=#{handler := Handler, handler_opts := HandlerOpts}, Ctx) ->
TraceId = otel_span:hex_trace_id(otel_tracer:current_span_ctx()),
Req = Req0#{<<"trace-id">> => TraceId},
try Handler:init(Req, HandlerOpts) of
{ok, Req2, State} ->
Headers0 = maps:get(headers, Req2),
Headers = otel_propagator_text_map:inject(Headers0,
fun(Headers, Key, Value) ->
maps:put(Key, Value, Headers)
end),
Req3 = maps:put(headers, Headers, Req2),
Result = terminate(normal, Req3, State, Handler),
{ok, Req3, Env#{result => Result, trace_id => TraceId}};
{Mod, Req2, State} ->
?add_event(<<"HTTP_UPGRADE">>, #{module => Mod}),
Mod:upgrade(Req2, Env, Handler, State);
{Mod, Req2, State, Opts} ->
?add_event(<<"HTTP_UPGRADE">>, #{module => Mod}),
Mod:upgrade(Req2, Env, Handler, State, Opts)
catch Class:Reason:Stacktrace ->
?set_status(error, iolist_to_binary([atom_to_binary(Class)])),
render_error(Class, Reason, Stacktrace, Handler, Req, Env, Ctx)
end.
render_error(Class, Reason, Stacktrace, Handler, Req, Env, Ctx) ->
ReasonS = lists:flatten(io_lib:format("~p", [Reason])),
Assigns = [
{dreki_node, node()},
{site_title, "Dreki"},
{class, atom_to_binary(Class)},
{reason, ReasonS},
{stacktrace, [lists:flatten(io_lib:format("~p", [Line])) || Line <- Stacktrace]},
{trace_id, maps:get(<<"trace-id">>, Req, <<"no-trace">>)}
],
logger:error(#{app => dreki_web, handler => Handler, error => {Class, Reason, Stacktrace}}),
{ok, Html} = crash_dtl:render(Assigns),
cowboy_req:reply(500, #{<<"content-type">> => <<"text/html">>}, Html, Req).
-spec terminate(any(), Req | undefined, any(), module()) -> ok when Req::cowboy_req:req().
terminate(Reason, Req, State, Handler) ->
case erlang:function_exported(Handler, terminate, 3) of
true ->
Handler:terminate(Reason, Req, State);
false ->
ok
end.
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