feat(prom): support configuring job_name for pushing mode

apps/emqx_prometheus/i18n/emqx_prometheus_schema_i18n.conf

@@ -34,6 +34,25 @@ For example, <code> { Authorization = "some-authz-tokens"}</code>"""
     }
   }
 
+  job_name {
+    desc {
+      en: """Job Name that is pushed to the Push Gateway. Available variables:<br/>
+- ${name}: Name of EMQX node.<br/>
+- ${host}: Host name of EMQX node.<br/>
+For example, when the EMQX node name is <code>emqx@127.0.0.1</code> then the <code>name</code> variable takes value <code>emqx</code> and the <code>host</code> variable takes value <code>127.0.0.1</code>.<br/>
+
+Default value is: <code>${name}/instance/${name}~${host}</code>
+"""
+      zh: """推送到 Push Gateway 的 Job 名称。可用变量为：<br/>
+- ${name}: EMQX 节点的名称。
+- ${host}: EMQX 节点主机名。
+
+例如，当 EMQX 节点名为 <code>emqx@127.0.0.1</code> 则 name 变量的值为 <code>emqx</code>，host 变量的值为 <code>127.0.0.1</code>。<br/>
+
+默认值为: <code>${name}/instance/${name}~${host}</code>"""
+    }
+  }
+
   enable {
     desc {
       en: """Turn Prometheus data pushing on or off"""

apps/emqx_prometheus/src/emqx_prometheus.erl

@@ -101,9 +101,10 @@ handle_info({timeout, Timer, ?TIMER_MSG}, State = #{timer := Timer}) ->
     #{
         interval := Interval,
         headers := Headers,
+        job_name := JobName,
         push_gateway_server := Server
     } = opts(),
-    PushRes = push_to_push_gateway(Server, Headers),
+    PushRes = push_to_push_gateway(Server, Headers, JobName),
     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.
@@ -111,9 +112,17 @@ handle_info({timeout, Timer, ?TIMER_MSG}, State = #{timer := Timer}) ->
 handle_info(_Msg, State) ->
     {noreply, State}.
 
-push_to_push_gateway(Uri, Headers0) when is_map(Headers0) ->
+push_to_push_gateway(Uri, Headers0, JobName) when is_map(Headers0) ->
     [Name, Ip] = string:tokens(atom_to_list(node()), "@"),
-    Url = lists:concat([Uri, "/metrics/job/", Name, "/instance/", Name, "~", Ip]),
+    JobName1 = emqx_placeholder:preproc_tmpl(JobName),
+    JobName2 = binary_to_list(
+        emqx_placeholder:proc_tmpl(
+            JobName1,
+            #{<<"name">> => Name, <<"host">> => Ip}
+        )
+    ),
+
+    Url = lists:concat([Uri, "/metrics/job/", JobName2]),
     Data = prometheus_text_format:format(),
     Headers = maps:fold(
         fun(K, V, Acc) ->

apps/emqx_prometheus/src/emqx_prometheus_api.erl

@@ -122,6 +122,7 @@ prometheus_config_example() ->
         interval => "15s",
         push_gateway_server => <<"http://127.0.0.1:9091">>,
         headers => #{'header-name' => 'header-value'},
+        job_name => <<"${name}/instance/${name}~${host}">>,
         vm_dist_collector => enabled,
         mnesia_collector => enabled,
         vm_statistics_collector => enabled,

apps/emqx_prometheus/src/emqx_prometheus_schema.erl

@@ -61,6 +61,16 @@ fields("prometheus") ->
                     desc => ?DESC(headers)
                 }
             )},
+        {job_name,
+            ?HOCON(
+                binary(),
+                #{
+                    default => <<"${name}/instance/${name}~${host}">>,
+                    required => true,
+                    desc => ?DESC(job_name)
+                }
+            )},
+
         {enable,
             ?HOCON(
                 boolean(),

apps/emqx_prometheus/test/emqx_prometheus_SUITE.erl

@@ -28,6 +28,7 @@
     "  push_gateway_server = \"http://127.0.0.1:9091\"\n"
     "  interval = \"1s\"\n"
     "  headers = { Authorization = \"some-authz-tokens\"}\n"
+    "  job_name = \"${name}~${host}\"\n"
     "  enable = true\n"
     "  vm_dist_collector = enabled\n"
     "  mnesia_collector = enabled\n"
@@ -91,7 +92,7 @@ t_assert_push(_) ->
     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),
+        ?assertMatch("http://127.0.0.1:9091/metrics/job/test~127.0.0.1", Url),
         ?assertEqual([{"Authorization", "some-authz-tokens"}], Headers),
         ?assertEqual("text/plain", ContentType),
         Self ! pass,