feat(prom): support headers for pushing

apps/emqx_prometheus/i18n/emqx_prometheus_schema_i18n.conf

@@ -24,6 +24,16 @@ emqx_prometheus_schema {
       zh: """数据推送间隔"""
     }
   }
+
+  headers {
+    desc {
+      en: """A list of HTTP Headers when pushing to Push Gateway.<br/>
+For example, <code> { Authorization = "some-authz-tokens"}</code>"""
+      zh: """推送到 Push Gateway 的 HTTP Headers 列表。<br/>
+例如，<code> { Authorization = "some-authz-tokens"}</code>"""
+    }
+  }
+
   enable {
     desc {
       en: """Turn Prometheus data pushing on or off"""

apps/emqx_prometheus/src/emqx_prometheus.erl

@@ -98,8 +98,12 @@ handle_cast(_Msg, State) ->
     {noreply, State}.
 
 handle_info({timeout, Timer, ?TIMER_MSG}, State = #{timer := Timer}) ->
-    #{interval := Interval, push_gateway_server := Server} = opts(),
+    #{
-    PushRes = push_to_push_gateway(Server),
+        interval := Interval,
+        headers := Headers,
+        push_gateway_server := Server
+    } = opts(),
+    PushRes = push_to_push_gateway(Server, Headers),
     NewTimer = ensure_timer(Interval),
     NewState = maps:update_with(PushRes, fun(C) -> C + 1 end, 1, State#{timer => NewTimer}),
     %% Data is too big, hibernate for saving memory and stop system monitor warning.
@@ -107,12 +111,19 @@ handle_info({timeout, Timer, ?TIMER_MSG}, State = #{timer := Timer}) ->
 handle_info(_Msg, State) ->
     {noreply, State}.
 
-push_to_push_gateway(Uri) ->
+push_to_push_gateway(Uri, Headers0) when is_map(Headers0) ->
     [Name, Ip] = string:tokens(atom_to_list(node()), "@"),
     Url = lists:concat([Uri, "/metrics/job/", Name, "/instance/", Name, "~", Ip]),
     Data = prometheus_text_format:format(),
-    case httpc:request(post, {Url, [], "text/plain", Data}, ?HTTP_OPTIONS, []) of
+    Headers = maps:fold(
-        {ok, {{"HTTP/1.1", 200, "OK"}, _Headers, _Body}} ->
+        fun(K, V, Acc) ->
+            [{atom_to_list(K), binary_to_list(V)} | Acc]
+        end,
+        [],
+        Headers0
+    ),
+    case httpc:request(post, {Url, Headers, "text/plain", Data}, ?HTTP_OPTIONS, []) of
+        {ok, {{"HTTP/1.1", 200, _}, _Headers, _Body}} ->
             ok;
         Error ->
             ?SLOG(error, #{

apps/emqx_prometheus/src/emqx_prometheus_api.erl

@@ -121,6 +121,7 @@ prometheus_config_example() ->
         enable => true,
         interval => "15s",
         push_gateway_server => <<"http://127.0.0.1:9091">>,
+        headers => #{'header-name' => 'header-value'},
         vm_dist_collector => enabled,
         mnesia_collector => enabled,
         vm_statistics_collector => enabled,

apps/emqx_prometheus/src/emqx_prometheus_schema.erl

@@ -52,6 +52,15 @@ fields("prometheus") ->
                     desc => ?DESC(interval)
                 }
             )},
+        {headers,
+            ?HOCON(
+                map(),
+                #{
+                    default => #{},
+                    required => false,
+                    desc => ?DESC(headers)
+                }
+            )},
         {enable,
             ?HOCON(
                 boolean(),

apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl

@@ -27,6 +27,7 @@
     "prometheus {\n"
     "  push_gateway_server = \"http://127.0.0.1:9091\"\n"
     "  interval = \"1s\"\n"
+    "  headers = { Authorization = \"some-authz-tokens\"}\n"
     "  enable = true\n"
     "  vm_dist_collector = enabled\n"
     "  mnesia_collector = enabled\n"
@@ -85,6 +86,25 @@ t_collector_no_crash_test(_) ->
     prometheus_text_format:format(),
     ok.
 
+t_assert_push(_) ->
+    meck:new(httpc, [passthrough]),
+    Self = self(),
+    AssertPush = fun(Method, Req = {Url, Headers, ContentType, _Data}, HttpOpts, Opts) ->
+        ?assertEqual(post, Method),
+        ?assertMatch("http://127.0.0.1:9091/metrics/job/" ++ _, Url),
+        ?assertEqual([{"Authorization", "some-authz-tokens"}], Headers),
+        ?assertEqual("text/plain", ContentType),
+        Self ! pass,
+        meck:passthrough([Method, Req, HttpOpts, Opts])
+    end,
+    meck:expect(httpc, request, AssertPush),
+    ?assertMatch(ok, emqx_prometheus_sup:start_child(emqx_prometheus)),
+    receive
+        pass -> ok
+    after 2000 ->
+        ct:fail(assert_push_request_failed)
+    end.
+
 t_only_for_coverage(_) ->
     ?assertEqual("5.0.0", emqx_prometheus_proto_v1:introduced_in()),
     ok.