From 8485ebb62595d440c3c2172206c8c7b1f5c5b803 Mon Sep 17 00:00:00 2001
From: Nelson Vides <nelson.vides@erlang-solutions.com>
Date: Fri, 28 Jul 2023 15:34:06 +0200
Subject: [PATCH] Reorder app startup

First config, then metrics, then everything else, including dependent metrics at the end
---
 src/ejabberd_app.erl                         |  5 +-
 src/metrics/mongoose_metrics.erl             | 51 +++++++++++++-------
 src/metrics/mongoose_metrics_definitions.hrl | 10 ++--
 3 files changed, 43 insertions(+), 23 deletions(-)

diff --git a/src/ejabberd_app.erl b/src/ejabberd_app.erl
index a5d6b4cb17a..df8d6fcb0c9 100644
--- a/src/ejabberd_app.erl
+++ b/src/ejabberd_app.erl
@@ -43,6 +43,8 @@ start(normal, _Args) ->
     mongoose_fips:notify(),
     write_pid_file(),
     update_status_file(starting),
+    mongoose_config:start(),
+    mongoose_metrics:init(),
     db_init(),
     application:start(cache_tab),
 
@@ -51,7 +53,6 @@ start(normal, _Args) ->
     ejabberd_node_id:start(),
     ejabberd_commands:init(),
     mongoose_graphql_commands:start(),
-    mongoose_config:start(),
     mongoose_router:start(),
     mongoose_logs:set_global_loglevel(mongoose_config:get_opt(loglevel)),
     mongoose_deprecations:start(),
@@ -67,9 +68,9 @@ start(normal, _Args) ->
     mongoose_service:start(),
     mongoose_modules:start(),
     service_mongoose_system_metrics:verify_if_configured(),
-    mongoose_metrics:init(),
     mongoose_listener:start(),
     ejabberd_admin:start(),
+    mongoose_metrics:init_mongooseim_metrics(),
     update_status_file(started),
     ?LOG_NOTICE(#{what => mongooseim_node_started, version => ?MONGOOSE_VERSION, node => node()}),
     Sup;
diff --git a/src/metrics/mongoose_metrics.erl b/src/metrics/mongoose_metrics.erl
index 4c4eb7ae431..7665bdd8166 100644
--- a/src/metrics/mongoose_metrics.erl
+++ b/src/metrics/mongoose_metrics.erl
@@ -20,6 +20,7 @@
 
 %% API
 -export([init/0,
+         init_mongooseim_metrics/0,
          create_generic_hook_metric/2,
          create_probe_metric/3,
          ensure_db_pool_metric/1,
@@ -65,24 +66,16 @@
 -spec init() -> ok.
 init() ->
     prepare_prefixes(),
-    create_global_metrics(),
-    lists:foreach(fun init_predefined_host_type_metrics/1, ?ALL_HOST_TYPES),
+    create_vm_metrics(),
+    create_global_metrics(?GLOBAL_COUNTERS),
+    create_data_metrics(),
+    create_host_type_metrics(),
     init_subscriptions().
 
-create_global_metrics() ->
-    lists:foreach(fun({Metric, FunSpec, DataPoints}) ->
-        FunSpecTuple = list_to_tuple(FunSpec ++ [DataPoints]),
-        catch ensure_metric(global, Metric, FunSpecTuple)
-    end, ?VM_STATS),
-    lists:foreach(fun({Metric, Spec}) -> ensure_metric(global, Metric, Spec) end,
-                  ?GLOBAL_COUNTERS),
-    create_data_metrics().
-
--spec init_predefined_host_type_metrics(mongooseim:host_type()) -> ok.
-init_predefined_host_type_metrics(HostType) ->
-    create_metrics(HostType),
-    Hooks = mongoose_metrics_hooks:get_hooks(HostType),
-    gen_hook:add_handlers(Hooks).
+-spec init_mongooseim_metrics() -> ok.
+init_mongooseim_metrics() ->
+    create_host_type_hook_metrics(),
+    create_global_metrics(?MNESIA_COUNTERS).
 
 init_subscriptions() ->
     Reporters = exometer_report:list_reporters(),
@@ -397,12 +390,34 @@ filter_hook(mam_muc_flush_messages) -> skip;
 
 filter_hook(_) -> use.
 
--spec create_metrics(mongooseim:host_type()) -> 'ok'.
-create_metrics(HostType) ->
+create_global_metrics(Metrics) ->
+    lists:foreach(fun({Metric, Spec}) -> ensure_metric(global, Metric, Spec) end, Metrics).
+
+create_vm_metrics() ->
+    lists:foreach(fun({Metric, FunSpec, DataPoints}) ->
+                          FunSpecTuple = list_to_tuple(FunSpec ++ [DataPoints]),
+                          catch ensure_metric(global, Metric, FunSpecTuple)
+                  end, ?VM_STATS).
+
+-spec create_host_type_metrics() -> ok.
+create_host_type_metrics() ->
+    lists:foreach(fun create_host_type_metrics/1, ?ALL_HOST_TYPES).
+
+-spec create_host_type_metrics(mongooseim:host_type()) -> 'ok'.
+create_host_type_metrics(HostType) ->
     lists:foreach(fun(Name) -> ensure_metric(HostType, Name, spiral) end, ?GENERAL_SPIRALS),
     lists:foreach(fun(Name) -> ensure_metric(HostType, Name, histogram) end, ?GENERAL_HISTOGRAMS),
     lists:foreach(fun(Name) -> ensure_metric(HostType, Name, counter) end, ?TOTAL_COUNTERS).
 
+-spec create_host_type_hook_metrics() -> ok.
+create_host_type_hook_metrics() ->
+    lists:foreach(fun create_host_type_hook_metrics/1, ?ALL_HOST_TYPES).
+
+-spec create_host_type_hook_metrics(mongooseim:host_type()) -> 'ok'.
+create_host_type_hook_metrics(HostType) ->
+    Hooks = mongoose_metrics_hooks:get_hooks(HostType),
+    gen_hook:add_handlers(Hooks).
+
 ensure_metric(HostType, Metric, Type, ShortType) when is_atom(Metric) ->
     ensure_metric(HostType, [Metric], Type, ShortType);
 
diff --git a/src/metrics/mongoose_metrics_definitions.hrl b/src/metrics/mongoose_metrics_definitions.hrl
index 0b1cfc199b4..7bb317252fa 100644
--- a/src/metrics/mongoose_metrics_definitions.hrl
+++ b/src/metrics/mongoose_metrics_definitions.hrl
@@ -65,14 +65,18 @@
         [{nodeUpTime,
           {function, mongoose_metrics, get_up_time, [],
            tagged, [value]}},
-         {clusterSize,
-          {function, mongoose_metrics, get_mnesia_running_db_nodes_count, [],
-           tagged, [value]}},
          ?PROBE(tcpPortsUsed, mongoose_metrics_probe_tcp),
          ?PROBE(processQueueLengths, mongoose_metrics_probe_queues)
         ]
 ).
 
+-define(MNESIA_COUNTERS,
+        [{clusterSize,
+          {function, mongoose_metrics, get_mnesia_running_db_nodes_count, [],
+           tagged, [value]}}
+        ]
+).
+
 -define(VM_STATS, [{[erlang, system_info], [function, erlang, system_info, ['$dp'], value],
                     [port_count, port_limit, process_count, process_limit, ets_limit]},
                    {[erlang, memory], [function, erlang, memory, ['$dp'], value],