1 files changed, 99 insertions, 0 deletions
diff --git a/apps/dreki_web/src/dreki_web_handler.erl b/apps/dreki_web/src/dreki_web_handler.erl
new file mode 100644
index 0000000..a30fd1d
--- /dev/null
+++ b/apps/dreki_web/src/dreki_web_handler.erl
@@ -0,0 +1,99 @@
+%% 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.