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Posted to notifications@couchdb.apache.org by GitBox <gi...@apache.org> on 2021/03/19 16:25:34 UTC
[GitHub] [couchdb] rnewson commented on a change in pull request #3416: Prometheus endpoint
rnewson commented on a change in pull request #3416:
URL: https://github.com/apache/couchdb/pull/3416#discussion_r597809665
##########
File path: src/chttpd/src/chttpd_node.erl
##########
@@ -117,6 +117,12 @@ handle_node_req(#httpd{method='GET', path_parts=[_, Node, <<"_stats">> | Path]}=
chttpd:send_json(Req, EJSON1);
handle_node_req(#httpd{path_parts=[_, _Node, <<"_stats">>]}=Req) ->
send_method_not_allowed(Req, "GET");
+handle_node_req(#httpd{method='GET', path_parts=[_, Node, <<"_prometheus">>]}=Req) ->
+ Metrics = call_node(Node, couch_prometheus_server, scrape, []),
+ Header = [{<<"Content-Type">>, <<"text/plain">>}],
Review comment:
I think there's supposed to be a version parameter on this?
##########
File path: src/couch_prometheus/src/couch_prometheus_http.erl
##########
@@ -0,0 +1,79 @@
+-module(couch_prometheus_http).
+
+-compile(tuple_calls).
+
+-export([
+ start_link/0,
+ handle_request/1
+]).
+
+-include("couch_prometheus.hrl").
+
+start_link() ->
+ IP = case config:get("prometheus", "bind_address", "any") of
+ "any" -> any;
+ Else -> Else
+ end,
+ Port = config:get("prometheus", "port"),
+ ok = couch_httpd:validate_bind_address(IP),
+
+ Options = [
+ {name, ?MODULE},
+ {loop, fun ?MODULE:handle_request/1},
+ {ip, IP},
+ {port, Port}
+ ],
+ case mochiweb_http:start(Options) of
+ {ok, Pid} ->
+ {ok, Pid};
+ {error, Reason} ->
+ io:format("Failure to start Mochiweb: ~s~n", [Reason]),
+ {error, Reason}
+ end.
+
+handle_request(MochiReq) ->
+ RawUri = MochiReq:get(raw_path),
+ {"/" ++ Path, _, _} = mochiweb_util:urlsplit_path(RawUri),
+ PathParts = string:tokens(Path, "/"), try
+ case PathParts of
+ ["_node", Node, "_prometheus"] ->
+ send_prometheus(MochiReq, Node);
+ _ ->
+ send_resp(MochiReq, 404, [], <<>>)
+ end
+ catch T:R ->
+ Body = io_lib:format("~p:~p", [T, R]),
+ send_resp(MochiReq, 500, [], Body)
Review comment:
we work hard elsewhere not to send ugly errors to the user, can we follow the chttpd:send_error pattern here?
##########
File path: src/couch_prometheus/src/couch_prometheus_sup.erl
##########
@@ -0,0 +1,39 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+% http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_prometheus_sup).
+
+-behaviour(supervisor).
+
+-export([
+ start_link/0,
+ init/1
+]).
+
+-define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
+
+start_link() ->
+ supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+init([]) ->
+ {ok, {
+ {one_for_one, 5, 10}, [
Review comment:
how were these numbers chosen?
##########
File path: src/couch_prometheus/src/couch_prometheus_server.erl
##########
@@ -0,0 +1,167 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+% http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_prometheus_server).
+
+-behaviour(gen_server).
+
+-import(couch_prometheus_util, [
+ couch_to_prom/3,
+ to_prom/3,
+ to_prom_summary/2
+]).
+
+-export([
+ start_link/0,
+ init/1,
+ handle_call/3,
+ handle_cast/2,
+ handle_info/2,
+ code_change/3,
+ terminate/2,
+
+ scrape/0
Review comment:
can we keep the gen_server callbacks in a separate export block to public or private functions pls? we do that ~everywhere else.
##########
File path: src/couch_prometheus/src/couch_prometheus_http.erl
##########
@@ -0,0 +1,79 @@
+-module(couch_prometheus_http).
+
+-compile(tuple_calls).
+
+-export([
+ start_link/0,
+ handle_request/1
+]).
+
+-include("couch_prometheus.hrl").
+
+start_link() ->
+ IP = case config:get("prometheus", "bind_address", "any") of
+ "any" -> any;
+ Else -> Else
+ end,
+ Port = config:get("prometheus", "port"),
+ ok = couch_httpd:validate_bind_address(IP),
+
+ Options = [
+ {name, ?MODULE},
+ {loop, fun ?MODULE:handle_request/1},
+ {ip, IP},
+ {port, Port}
+ ],
+ case mochiweb_http:start(Options) of
+ {ok, Pid} ->
+ {ok, Pid};
+ {error, Reason} ->
+ io:format("Failure to start Mochiweb: ~s~n", [Reason]),
+ {error, Reason}
+ end.
+
+handle_request(MochiReq) ->
+ RawUri = MochiReq:get(raw_path),
+ {"/" ++ Path, _, _} = mochiweb_util:urlsplit_path(RawUri),
+ PathParts = string:tokens(Path, "/"), try
+ case PathParts of
+ ["_node", Node, "_prometheus"] ->
+ send_prometheus(MochiReq, Node);
+ _ ->
+ send_resp(MochiReq, 404, [], <<>>)
+ end
+ catch T:R ->
+ Body = io_lib:format("~p:~p", [T, R]),
+ send_resp(MochiReq, 500, [], Body)
+ end.
+
+send_prometheus(MochiReq, Node) ->
+ Headers = couch_httpd:server_header() ++ [
+ {<<"Content-Type">>, <<"text/plain">>}
Review comment:
version param?
##########
File path: src/couch_prometheus/src/couch_prometheus_server.erl
##########
@@ -0,0 +1,167 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+% http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_prometheus_server).
+
+-behaviour(gen_server).
+
+-import(couch_prometheus_util, [
+ couch_to_prom/3,
+ to_prom/3,
+ to_prom_summary/2
+]).
+
+-export([
+ start_link/0,
+ init/1,
+ handle_call/3,
+ handle_cast/2,
+ handle_info/2,
+ code_change/3,
+ terminate/2,
+
+ scrape/0
+]).
+
+-include("couch_prometheus.hrl").
+
+start_link() ->
+ gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+
+-record(st, {
+ metrics,
+ refresh
+}).
+
+init([]) ->
+ Metrics = refresh_metrics(),
+ RT = update_refresh_timer(),
+ {ok, #st{metrics=Metrics, refresh=RT}}.
+
+scrape() ->
+ {ok, Metrics} = gen_server:call(?MODULE, scrape),
Review comment:
will this ever take >5s?
##########
File path: src/couch_prometheus/src/couch_prometheus_sup.erl
##########
@@ -0,0 +1,39 @@
+% Licensed under the Apache License, Version 2.0 (the "License"); you may not
+% use this file except in compliance with the License. You may obtain a copy of
+% the License at
+%
+% http://www.apache.org/licenses/LICENSE-2.0
+%
+% Unless required by applicable law or agreed to in writing, software
+% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+% License for the specific language governing permissions and limitations under
+% the License.
+
+-module(couch_prometheus_sup).
+
+-behaviour(supervisor).
+
+-export([
+ start_link/0,
+ init/1
+]).
+
+-define(CHILD(I, Type), {I, {I, start_link, []}, permanent, 5000, Type, [I]}).
+
+start_link() ->
+ supervisor:start_link({local, ?MODULE}, ?MODULE, []).
+
+init([]) ->
+ {ok, {
+ {one_for_one, 5, 10}, [
Review comment:
if the couch_prometheus_server process crashing should the couch_prometheus_http be restarted? (i.e, rest_for_one).
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